Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4121 insertions, 0 deletions

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
new file mode 100644
index 0000000000..bed3cefdaf
--- /dev/null
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -0,0 +1,4121 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Author:
+ *   Jake Oshins <jakeo@microsoft.com>
+ *
+ * This driver acts as a paravirtual front-end for PCI Express root buses.
+ * When a PCI Express function (either an entire device or an SR-IOV
+ * Virtual Function) is being passed through to the VM, this driver exposes
+ * a new bus to the guest VM.  This is modeled as a root PCI bus because
+ * no bridges are being exposed to the VM.  In fact, with a "Generation 2"
+ * VM within Hyper-V, there may seem to be no PCI bus at all in the VM
+ * until a device as been exposed using this driver.
+ *
+ * Each root PCI bus has its own PCI domain, which is called "Segment" in
+ * the PCI Firmware Specifications.  Thus while each device passed through
+ * to the VM using this front-end will appear at "device 0", the domain will
+ * be unique.  Typically, each bus will have one PCI function on it, though
+ * this driver does support more than one.
+ *
+ * In order to map the interrupts from the device through to the guest VM,
+ * this driver also implements an IRQ Domain, which handles interrupts (either
+ * MSI or MSI-X) associated with the functions on the bus.  As interrupts are
+ * set up, torn down, or reaffined, this driver communicates with the
+ * underlying hypervisor to adjust the mappings in the I/O MMU so that each
+ * interrupt will be delivered to the correct virtual processor at the right
+ * vector.  This driver does not support level-triggered (line-based)
+ * interrupts, and will report that the Interrupt Line register in the
+ * function's configuration space is zero.
+ *
+ * The rest of this driver mostly maps PCI concepts onto underlying Hyper-V
+ * facilities.  For instance, the configuration space of a function exposed
+ * by Hyper-V is mapped into a single page of memory space, and the
+ * read and write handlers for config space must be aware of this mechanism.
+ * Similarly, device setup and teardown involves messages sent to and from
+ * the PCI back-end driver in Hyper-V.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci-ecam.h>
+#include <linux/delay.h>
+#include <linux/semaphore.h>
+#include <linux/irq.h>
+#include <linux/msi.h>
+#include <linux/hyperv.h>
+#include <linux/refcount.h>
+#include <linux/irqdomain.h>
+#include <linux/acpi.h>
+#include <asm/mshyperv.h>
+
+/*
+ * Protocol versions. The low word is the minor version, the high word the
+ * major version.
+ */
+
+#define PCI_MAKE_VERSION(major, minor) ((u32)(((major) << 16) | (minor)))
+#define PCI_MAJOR_VERSION(version) ((u32)(version) >> 16)
+#define PCI_MINOR_VERSION(version) ((u32)(version) & 0xff)
+
+enum pci_protocol_version_t {
+	PCI_PROTOCOL_VERSION_1_1 = PCI_MAKE_VERSION(1, 1),	/* Win10 */
+	PCI_PROTOCOL_VERSION_1_2 = PCI_MAKE_VERSION(1, 2),	/* RS1 */
+	PCI_PROTOCOL_VERSION_1_3 = PCI_MAKE_VERSION(1, 3),	/* Vibranium */
+	PCI_PROTOCOL_VERSION_1_4 = PCI_MAKE_VERSION(1, 4),	/* WS2022 */
+};
+
+#define CPU_AFFINITY_ALL	-1ULL
+
+/*
+ * Supported protocol versions in the order of probing - highest go
+ * first.
+ */
+static enum pci_protocol_version_t pci_protocol_versions[] = {
+	PCI_PROTOCOL_VERSION_1_4,
+	PCI_PROTOCOL_VERSION_1_3,
+	PCI_PROTOCOL_VERSION_1_2,
+	PCI_PROTOCOL_VERSION_1_1,
+};
+
+#define PCI_CONFIG_MMIO_LENGTH	0x2000
+#define CFG_PAGE_OFFSET 0x1000
+#define CFG_PAGE_SIZE (PCI_CONFIG_MMIO_LENGTH - CFG_PAGE_OFFSET)
+
+#define MAX_SUPPORTED_MSI_MESSAGES 0x400
+
+#define STATUS_REVISION_MISMATCH 0xC0000059
+
+/* space for 32bit serial number as string */
+#define SLOT_NAME_SIZE 11
+
+/*
+ * Size of requestor for VMbus; the value is based on the observation
+ * that having more than one request outstanding is 'rare', and so 64
+ * should be generous in ensuring that we don't ever run out.
+ */
+#define HV_PCI_RQSTOR_SIZE 64
+
+/*
+ * Message Types
+ */
+
+enum pci_message_type {
+	/*
+	 * Version 1.1
+	 */
+	PCI_MESSAGE_BASE                = 0x42490000,
+	PCI_BUS_RELATIONS               = PCI_MESSAGE_BASE + 0,
+	PCI_QUERY_BUS_RELATIONS         = PCI_MESSAGE_BASE + 1,
+	PCI_POWER_STATE_CHANGE          = PCI_MESSAGE_BASE + 4,
+	PCI_QUERY_RESOURCE_REQUIREMENTS = PCI_MESSAGE_BASE + 5,
+	PCI_QUERY_RESOURCE_RESOURCES    = PCI_MESSAGE_BASE + 6,
+	PCI_BUS_D0ENTRY                 = PCI_MESSAGE_BASE + 7,
+	PCI_BUS_D0EXIT                  = PCI_MESSAGE_BASE + 8,
+	PCI_READ_BLOCK                  = PCI_MESSAGE_BASE + 9,
+	PCI_WRITE_BLOCK                 = PCI_MESSAGE_BASE + 0xA,
+	PCI_EJECT                       = PCI_MESSAGE_BASE + 0xB,
+	PCI_QUERY_STOP                  = PCI_MESSAGE_BASE + 0xC,
+	PCI_REENABLE                    = PCI_MESSAGE_BASE + 0xD,
+	PCI_QUERY_STOP_FAILED           = PCI_MESSAGE_BASE + 0xE,
+	PCI_EJECTION_COMPLETE           = PCI_MESSAGE_BASE + 0xF,
+	PCI_RESOURCES_ASSIGNED          = PCI_MESSAGE_BASE + 0x10,
+	PCI_RESOURCES_RELEASED          = PCI_MESSAGE_BASE + 0x11,
+	PCI_INVALIDATE_BLOCK            = PCI_MESSAGE_BASE + 0x12,
+	PCI_QUERY_PROTOCOL_VERSION      = PCI_MESSAGE_BASE + 0x13,
+	PCI_CREATE_INTERRUPT_MESSAGE    = PCI_MESSAGE_BASE + 0x14,
+	PCI_DELETE_INTERRUPT_MESSAGE    = PCI_MESSAGE_BASE + 0x15,
+	PCI_RESOURCES_ASSIGNED2		= PCI_MESSAGE_BASE + 0x16,
+	PCI_CREATE_INTERRUPT_MESSAGE2	= PCI_MESSAGE_BASE + 0x17,
+	PCI_DELETE_INTERRUPT_MESSAGE2	= PCI_MESSAGE_BASE + 0x18, /* unused */
+	PCI_BUS_RELATIONS2		= PCI_MESSAGE_BASE + 0x19,
+	PCI_RESOURCES_ASSIGNED3         = PCI_MESSAGE_BASE + 0x1A,
+	PCI_CREATE_INTERRUPT_MESSAGE3   = PCI_MESSAGE_BASE + 0x1B,
+	PCI_MESSAGE_MAXIMUM
+};
+
+/*
+ * Structures defining the virtual PCI Express protocol.
+ */
+
+union pci_version {
+	struct {
+		u16 minor_version;
+		u16 major_version;
+	} parts;
+	u32 version;
+} __packed;
+
+/*
+ * Function numbers are 8-bits wide on Express, as interpreted through ARI,
+ * which is all this driver does.  This representation is the one used in
+ * Windows, which is what is expected when sending this back and forth with
+ * the Hyper-V parent partition.
+ */
+union win_slot_encoding {
+	struct {
+		u32	dev:5;
+		u32	func:3;
+		u32	reserved:24;
+	} bits;
+	u32 slot;
+} __packed;
+
+/*
+ * Pretty much as defined in the PCI Specifications.
+ */
+struct pci_function_description {
+	u16	v_id;	/* vendor ID */
+	u16	d_id;	/* device ID */
+	u8	rev;
+	u8	prog_intf;
+	u8	subclass;
+	u8	base_class;
+	u32	subsystem_id;
+	union win_slot_encoding win_slot;
+	u32	ser;	/* serial number */
+} __packed;
+
+enum pci_device_description_flags {
+	HV_PCI_DEVICE_FLAG_NONE			= 0x0,
+	HV_PCI_DEVICE_FLAG_NUMA_AFFINITY	= 0x1,
+};
+
+struct pci_function_description2 {
+	u16	v_id;	/* vendor ID */
+	u16	d_id;	/* device ID */
+	u8	rev;
+	u8	prog_intf;
+	u8	subclass;
+	u8	base_class;
+	u32	subsystem_id;
+	union	win_slot_encoding win_slot;
+	u32	ser;	/* serial number */
+	u32	flags;
+	u16	virtual_numa_node;
+	u16	reserved;
+} __packed;
+
+/**
+ * struct hv_msi_desc
+ * @vector:		IDT entry
+ * @delivery_mode:	As defined in Intel's Programmer's
+ *			Reference Manual, Volume 3, Chapter 8.
+ * @vector_count:	Number of contiguous entries in the
+ *			Interrupt Descriptor Table that are
+ *			occupied by this Message-Signaled
+ *			Interrupt. For "MSI", as first defined
+ *			in PCI 2.2, this can be between 1 and
+ *			32. For "MSI-X," as first defined in PCI
+ *			3.0, this must be 1, as each MSI-X table
+ *			entry would have its own descriptor.
+ * @reserved:		Empty space
+ * @cpu_mask:		All the target virtual processors.
+ */
+struct hv_msi_desc {
+	u8	vector;
+	u8	delivery_mode;
+	u16	vector_count;
+	u32	reserved;
+	u64	cpu_mask;
+} __packed;
+
+/**
+ * struct hv_msi_desc2 - 1.2 version of hv_msi_desc
+ * @vector:		IDT entry
+ * @delivery_mode:	As defined in Intel's Programmer's
+ *			Reference Manual, Volume 3, Chapter 8.
+ * @vector_count:	Number of contiguous entries in the
+ *			Interrupt Descriptor Table that are
+ *			occupied by this Message-Signaled
+ *			Interrupt. For "MSI", as first defined
+ *			in PCI 2.2, this can be between 1 and
+ *			32. For "MSI-X," as first defined in PCI
+ *			3.0, this must be 1, as each MSI-X table
+ *			entry would have its own descriptor.
+ * @processor_count:	number of bits enabled in array.
+ * @processor_array:	All the target virtual processors.
+ */
+struct hv_msi_desc2 {
+	u8	vector;
+	u8	delivery_mode;
+	u16	vector_count;
+	u16	processor_count;
+	u16	processor_array[32];
+} __packed;
+
+/*
+ * struct hv_msi_desc3 - 1.3 version of hv_msi_desc
+ *	Everything is the same as in 'hv_msi_desc2' except that the size of the
+ *	'vector' field is larger to support bigger vector values. For ex: LPI
+ *	vectors on ARM.
+ */
+struct hv_msi_desc3 {
+	u32	vector;
+	u8	delivery_mode;
+	u8	reserved;
+	u16	vector_count;
+	u16	processor_count;
+	u16	processor_array[32];
+} __packed;
+
+/**
+ * struct tran_int_desc
+ * @reserved:		unused, padding
+ * @vector_count:	same as in hv_msi_desc
+ * @data:		This is the "data payload" value that is
+ *			written by the device when it generates
+ *			a message-signaled interrupt, either MSI
+ *			or MSI-X.
+ * @address:		This is the address to which the data
+ *			payload is written on interrupt
+ *			generation.
+ */
+struct tran_int_desc {
+	u16	reserved;
+	u16	vector_count;
+	u32	data;
+	u64	address;
+} __packed;
+
+/*
+ * A generic message format for virtual PCI.
+ * Specific message formats are defined later in the file.
+ */
+
+struct pci_message {
+	u32 type;
+} __packed;
+
+struct pci_child_message {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+} __packed;
+
+struct pci_incoming_message {
+	struct vmpacket_descriptor hdr;
+	struct pci_message message_type;
+} __packed;
+
+struct pci_response {
+	struct vmpacket_descriptor hdr;
+	s32 status;			/* negative values are failures */
+} __packed;
+
+struct pci_packet {
+	void (*completion_func)(void *context, struct pci_response *resp,
+				int resp_packet_size);
+	void *compl_ctxt;
+
+	struct pci_message message[];
+};
+
+/*
+ * Specific message types supporting the PCI protocol.
+ */
+
+/*
+ * Version negotiation message. Sent from the guest to the host.
+ * The guest is free to try different versions until the host
+ * accepts the version.
+ *
+ * pci_version: The protocol version requested.
+ * is_last_attempt: If TRUE, this is the last version guest will request.
+ * reservedz: Reserved field, set to zero.
+ */
+
+struct pci_version_request {
+	struct pci_message message_type;
+	u32 protocol_version;
+} __packed;
+
+/*
+ * Bus D0 Entry.  This is sent from the guest to the host when the virtual
+ * bus (PCI Express port) is ready for action.
+ */
+
+struct pci_bus_d0_entry {
+	struct pci_message message_type;
+	u32 reserved;
+	u64 mmio_base;
+} __packed;
+
+struct pci_bus_relations {
+	struct pci_incoming_message incoming;
+	u32 device_count;
+	struct pci_function_description func[];
+} __packed;
+
+struct pci_bus_relations2 {
+	struct pci_incoming_message incoming;
+	u32 device_count;
+	struct pci_function_description2 func[];
+} __packed;
+
+struct pci_q_res_req_response {
+	struct vmpacket_descriptor hdr;
+	s32 status;			/* negative values are failures */
+	u32 probed_bar[PCI_STD_NUM_BARS];
+} __packed;
+
+struct pci_set_power {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	u32 power_state;		/* In Windows terms */
+	u32 reserved;
+} __packed;
+
+struct pci_set_power_response {
+	struct vmpacket_descriptor hdr;
+	s32 status;			/* negative values are failures */
+	union win_slot_encoding wslot;
+	u32 resultant_state;		/* In Windows terms */
+	u32 reserved;
+} __packed;
+
+struct pci_resources_assigned {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	u8 memory_range[0x14][6];	/* not used here */
+	u32 msi_descriptors;
+	u32 reserved[4];
+} __packed;
+
+struct pci_resources_assigned2 {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	u8 memory_range[0x14][6];	/* not used here */
+	u32 msi_descriptor_count;
+	u8 reserved[70];
+} __packed;
+
+struct pci_create_interrupt {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	struct hv_msi_desc int_desc;
+} __packed;
+
+struct pci_create_int_response {
+	struct pci_response response;
+	u32 reserved;
+	struct tran_int_desc int_desc;
+} __packed;
+
+struct pci_create_interrupt2 {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	struct hv_msi_desc2 int_desc;
+} __packed;
+
+struct pci_create_interrupt3 {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	struct hv_msi_desc3 int_desc;
+} __packed;
+
+struct pci_delete_interrupt {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	struct tran_int_desc int_desc;
+} __packed;
+
+/*
+ * Note: the VM must pass a valid block id, wslot and bytes_requested.
+ */
+struct pci_read_block {
+	struct pci_message message_type;
+	u32 block_id;
+	union win_slot_encoding wslot;
+	u32 bytes_requested;
+} __packed;
+
+struct pci_read_block_response {
+	struct vmpacket_descriptor hdr;
+	u32 status;
+	u8 bytes[HV_CONFIG_BLOCK_SIZE_MAX];
+} __packed;
+
+/*
+ * Note: the VM must pass a valid block id, wslot and byte_count.
+ */
+struct pci_write_block {
+	struct pci_message message_type;
+	u32 block_id;
+	union win_slot_encoding wslot;
+	u32 byte_count;
+	u8 bytes[HV_CONFIG_BLOCK_SIZE_MAX];
+} __packed;
+
+struct pci_dev_inval_block {
+	struct pci_incoming_message incoming;
+	union win_slot_encoding wslot;
+	u64 block_mask;
+} __packed;
+
+struct pci_dev_incoming {
+	struct pci_incoming_message incoming;
+	union win_slot_encoding wslot;
+} __packed;
+
+struct pci_eject_response {
+	struct pci_message message_type;
+	union win_slot_encoding wslot;
+	u32 status;
+} __packed;
+
+static int pci_ring_size = (4 * PAGE_SIZE);
+
+/*
+ * Driver specific state.
+ */
+
+enum hv_pcibus_state {
+	hv_pcibus_init = 0,
+	hv_pcibus_probed,
+	hv_pcibus_installed,
+	hv_pcibus_removing,
+	hv_pcibus_maximum
+};
+
+struct hv_pcibus_device {
+#ifdef CONFIG_X86
+	struct pci_sysdata sysdata;
+#elif defined(CONFIG_ARM64)
+	struct pci_config_window sysdata;
+#endif
+	struct pci_host_bridge *bridge;
+	struct fwnode_handle *fwnode;
+	/* Protocol version negotiated with the host */
+	enum pci_protocol_version_t protocol_version;
+
+	struct mutex state_lock;
+	enum hv_pcibus_state state;
+
+	struct hv_device *hdev;
+	resource_size_t low_mmio_space;
+	resource_size_t high_mmio_space;
+	struct resource *mem_config;
+	struct resource *low_mmio_res;
+	struct resource *high_mmio_res;
+	struct completion *survey_event;
+	struct pci_bus *pci_bus;
+	spinlock_t config_lock;	/* Avoid two threads writing index page */
+	spinlock_t device_list_lock;	/* Protect lists below */
+	void __iomem *cfg_addr;
+
+	struct list_head children;
+	struct list_head dr_list;
+
+	struct msi_domain_info msi_info;
+	struct irq_domain *irq_domain;
+
+	struct workqueue_struct *wq;
+
+	/* Highest slot of child device with resources allocated */
+	int wslot_res_allocated;
+	bool use_calls; /* Use hypercalls to access mmio cfg space */
+};
+
+/*
+ * Tracks "Device Relations" messages from the host, which must be both
+ * processed in order and deferred so that they don't run in the context
+ * of the incoming packet callback.
+ */
+struct hv_dr_work {
+	struct work_struct wrk;
+	struct hv_pcibus_device *bus;
+};
+
+struct hv_pcidev_description {
+	u16	v_id;	/* vendor ID */
+	u16	d_id;	/* device ID */
+	u8	rev;
+	u8	prog_intf;
+	u8	subclass;
+	u8	base_class;
+	u32	subsystem_id;
+	union	win_slot_encoding win_slot;
+	u32	ser;	/* serial number */
+	u32	flags;
+	u16	virtual_numa_node;
+};
+
+struct hv_dr_state {
+	struct list_head list_entry;
+	u32 device_count;
+	struct hv_pcidev_description func[];
+};
+
+struct hv_pci_dev {
+	/* List protected by pci_rescan_remove_lock */
+	struct list_head list_entry;
+	refcount_t refs;
+	struct pci_slot *pci_slot;
+	struct hv_pcidev_description desc;
+	bool reported_missing;
+	struct hv_pcibus_device *hbus;
+	struct work_struct wrk;
+
+	void (*block_invalidate)(void *context, u64 block_mask);
+	void *invalidate_context;
+
+	/*
+	 * What would be observed if one wrote 0xFFFFFFFF to a BAR and then
+	 * read it back, for each of the BAR offsets within config space.
+	 */
+	u32 probed_bar[PCI_STD_NUM_BARS];
+};
+
+struct hv_pci_compl {
+	struct completion host_event;
+	s32 completion_status;
+};
+
+static void hv_pci_onchannelcallback(void *context);
+
+#ifdef CONFIG_X86
+#define DELIVERY_MODE	APIC_DELIVERY_MODE_FIXED
+#define FLOW_HANDLER	handle_edge_irq
+#define FLOW_NAME	"edge"
+
+static int hv_pci_irqchip_init(void)
+{
+	return 0;
+}
+
+static struct irq_domain *hv_pci_get_root_domain(void)
+{
+	return x86_vector_domain;
+}
+
+static unsigned int hv_msi_get_int_vector(struct irq_data *data)
+{
+	struct irq_cfg *cfg = irqd_cfg(data);
+
+	return cfg->vector;
+}
+
+#define hv_msi_prepare		pci_msi_prepare
+
+/**
+ * hv_arch_irq_unmask() - "Unmask" the IRQ by setting its current
+ * affinity.
+ * @data:	Describes the IRQ
+ *
+ * Build new a destination for the MSI and make a hypercall to
+ * update the Interrupt Redirection Table. "Device Logical ID"
+ * is built out of this PCI bus's instance GUID and the function
+ * number of the device.
+ */
+static void hv_arch_irq_unmask(struct irq_data *data)
+{
+	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
+	struct hv_retarget_device_interrupt *params;
+	struct tran_int_desc *int_desc;
+	struct hv_pcibus_device *hbus;
+	const struct cpumask *dest;
+	cpumask_var_t tmp;
+	struct pci_bus *pbus;
+	struct pci_dev *pdev;
+	unsigned long flags;
+	u32 var_size = 0;
+	int cpu, nr_bank;
+	u64 res;
+
+	dest = irq_data_get_effective_affinity_mask(data);
+	pdev = msi_desc_to_pci_dev(msi_desc);
+	pbus = pdev->bus;
+	hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
+	int_desc = data->chip_data;
+	if (!int_desc) {
+		dev_warn(&hbus->hdev->device, "%s() can not unmask irq %u\n",
+			 __func__, data->irq);
+		return;
+	}
+
+	local_irq_save(flags);
+
+	params = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	memset(params, 0, sizeof(*params));
+	params->partition_id = HV_PARTITION_ID_SELF;
+	params->int_entry.source = HV_INTERRUPT_SOURCE_MSI;
+	params->int_entry.msi_entry.address.as_uint32 = int_desc->address & 0xffffffff;
+	params->int_entry.msi_entry.data.as_uint32 = int_desc->data;
+	params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
+			   (hbus->hdev->dev_instance.b[4] << 16) |
+			   (hbus->hdev->dev_instance.b[7] << 8) |
+			   (hbus->hdev->dev_instance.b[6] & 0xf8) |
+			   PCI_FUNC(pdev->devfn);
+	params->int_target.vector = hv_msi_get_int_vector(data);
+
+	/*
+	 * Honoring apic->delivery_mode set to APIC_DELIVERY_MODE_FIXED by
+	 * setting the HV_DEVICE_INTERRUPT_TARGET_MULTICAST flag results in a
+	 * spurious interrupt storm. Not doing so does not seem to have a
+	 * negative effect (yet?).
+	 */
+
+	if (hbus->protocol_version >= PCI_PROTOCOL_VERSION_1_2) {
+		/*
+		 * PCI_PROTOCOL_VERSION_1_2 supports the VP_SET version of the
+		 * HVCALL_RETARGET_INTERRUPT hypercall, which also coincides
+		 * with >64 VP support.
+		 * ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED
+		 * is not sufficient for this hypercall.
+		 */
+		params->int_target.flags |=
+			HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;
+
+		if (!alloc_cpumask_var(&tmp, GFP_ATOMIC)) {
+			res = 1;
+			goto out;
+		}
+
+		cpumask_and(tmp, dest, cpu_online_mask);
+		nr_bank = cpumask_to_vpset(&params->int_target.vp_set, tmp);
+		free_cpumask_var(tmp);
+
+		if (nr_bank <= 0) {
+			res = 1;
+			goto out;
+		}
+
+		/*
+		 * var-sized hypercall, var-size starts after vp_mask (thus
+		 * vp_set.format does not count, but vp_set.valid_bank_mask
+		 * does).
+		 */
+		var_size = 1 + nr_bank;
+	} else {
+		for_each_cpu_and(cpu, dest, cpu_online_mask) {
+			params->int_target.vp_mask |=
+				(1ULL << hv_cpu_number_to_vp_number(cpu));
+		}
+	}
+
+	res = hv_do_hypercall(HVCALL_RETARGET_INTERRUPT | (var_size << 17),
+			      params, NULL);
+
+out:
+	local_irq_restore(flags);
+
+	/*
+	 * During hibernation, when a CPU is offlined, the kernel tries
+	 * to move the interrupt to the remaining CPUs that haven't
+	 * been offlined yet. In this case, the below hv_do_hypercall()
+	 * always fails since the vmbus channel has been closed:
+	 * refer to cpu_disable_common() -> fixup_irqs() ->
+	 * irq_migrate_all_off_this_cpu() -> migrate_one_irq().
+	 *
+	 * Suppress the error message for hibernation because the failure
+	 * during hibernation does not matter (at this time all the devices
+	 * have been frozen). Note: the correct affinity info is still updated
+	 * into the irqdata data structure in migrate_one_irq() ->
+	 * irq_do_set_affinity(), so later when the VM resumes,
+	 * hv_pci_restore_msi_state() is able to correctly restore the
+	 * interrupt with the correct affinity.
+	 */
+	if (!hv_result_success(res) && hbus->state != hv_pcibus_removing)
+		dev_err(&hbus->hdev->device,
+			"%s() failed: %#llx", __func__, res);
+}
+#elif defined(CONFIG_ARM64)
+/*
+ * SPI vectors to use for vPCI; arch SPIs range is [32, 1019], but leaving a bit
+ * of room at the start to allow for SPIs to be specified through ACPI and
+ * starting with a power of two to satisfy power of 2 multi-MSI requirement.
+ */
+#define HV_PCI_MSI_SPI_START	64
+#define HV_PCI_MSI_SPI_NR	(1020 - HV_PCI_MSI_SPI_START)
+#define DELIVERY_MODE		0
+#define FLOW_HANDLER		NULL
+#define FLOW_NAME		NULL
+#define hv_msi_prepare		NULL
+
+struct hv_pci_chip_data {
+	DECLARE_BITMAP(spi_map, HV_PCI_MSI_SPI_NR);
+	struct mutex	map_lock;
+};
+
+/* Hyper-V vPCI MSI GIC IRQ domain */
+static struct irq_domain *hv_msi_gic_irq_domain;
+
+/* Hyper-V PCI MSI IRQ chip */
+static struct irq_chip hv_arm64_msi_irq_chip = {
+	.name = "MSI",
+	.irq_set_affinity = irq_chip_set_affinity_parent,
+	.irq_eoi = irq_chip_eoi_parent,
+	.irq_mask = irq_chip_mask_parent,
+	.irq_unmask = irq_chip_unmask_parent
+};
+
+static unsigned int hv_msi_get_int_vector(struct irq_data *irqd)
+{
+	return irqd->parent_data->hwirq;
+}
+
+/*
+ * @nr_bm_irqs:		Indicates the number of IRQs that were allocated from
+ *			the bitmap.
+ * @nr_dom_irqs:	Indicates the number of IRQs that were allocated from
+ *			the parent domain.
+ */
+static void hv_pci_vec_irq_free(struct irq_domain *domain,
+				unsigned int virq,
+				unsigned int nr_bm_irqs,
+				unsigned int nr_dom_irqs)
+{
+	struct hv_pci_chip_data *chip_data = domain->host_data;
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+	int first = d->hwirq - HV_PCI_MSI_SPI_START;
+	int i;
+
+	mutex_lock(&chip_data->map_lock);
+	bitmap_release_region(chip_data->spi_map,
+			      first,
+			      get_count_order(nr_bm_irqs));
+	mutex_unlock(&chip_data->map_lock);
+	for (i = 0; i < nr_dom_irqs; i++) {
+		if (i)
+			d = irq_domain_get_irq_data(domain, virq + i);
+		irq_domain_reset_irq_data(d);
+	}
+
+	irq_domain_free_irqs_parent(domain, virq, nr_dom_irqs);
+}
+
+static void hv_pci_vec_irq_domain_free(struct irq_domain *domain,
+				       unsigned int virq,
+				       unsigned int nr_irqs)
+{
+	hv_pci_vec_irq_free(domain, virq, nr_irqs, nr_irqs);
+}
+
+static int hv_pci_vec_alloc_device_irq(struct irq_domain *domain,
+				       unsigned int nr_irqs,
+				       irq_hw_number_t *hwirq)
+{
+	struct hv_pci_chip_data *chip_data = domain->host_data;
+	int index;
+
+	/* Find and allocate region from the SPI bitmap */
+	mutex_lock(&chip_data->map_lock);
+	index = bitmap_find_free_region(chip_data->spi_map,
+					HV_PCI_MSI_SPI_NR,
+					get_count_order(nr_irqs));
+	mutex_unlock(&chip_data->map_lock);
+	if (index < 0)
+		return -ENOSPC;
+
+	*hwirq = index + HV_PCI_MSI_SPI_START;
+
+	return 0;
+}
+
+static int hv_pci_vec_irq_gic_domain_alloc(struct irq_domain *domain,
+					   unsigned int virq,
+					   irq_hw_number_t hwirq)
+{
+	struct irq_fwspec fwspec;
+	struct irq_data *d;
+	int ret;
+
+	fwspec.fwnode = domain->parent->fwnode;
+	fwspec.param_count = 2;
+	fwspec.param[0] = hwirq;
+	fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
+
+	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
+	if (ret)
+		return ret;
+
+	/*
+	 * Since the interrupt specifier is not coming from ACPI or DT, the
+	 * trigger type will need to be set explicitly. Otherwise, it will be
+	 * set to whatever is in the GIC configuration.
+	 */
+	d = irq_domain_get_irq_data(domain->parent, virq);
+
+	return d->chip->irq_set_type(d, IRQ_TYPE_EDGE_RISING);
+}
+
+static int hv_pci_vec_irq_domain_alloc(struct irq_domain *domain,
+				       unsigned int virq, unsigned int nr_irqs,
+				       void *args)
+{
+	irq_hw_number_t hwirq;
+	unsigned int i;
+	int ret;
+
+	ret = hv_pci_vec_alloc_device_irq(domain, nr_irqs, &hwirq);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < nr_irqs; i++) {
+		ret = hv_pci_vec_irq_gic_domain_alloc(domain, virq + i,
+						      hwirq + i);
+		if (ret) {
+			hv_pci_vec_irq_free(domain, virq, nr_irqs, i);
+			return ret;
+		}
+
+		irq_domain_set_hwirq_and_chip(domain, virq + i,
+					      hwirq + i,
+					      &hv_arm64_msi_irq_chip,
+					      domain->host_data);
+		pr_debug("pID:%d vID:%u\n", (int)(hwirq + i), virq + i);
+	}
+
+	return 0;
+}
+
+/*
+ * Pick the first cpu as the irq affinity that can be temporarily used for
+ * composing MSI from the hypervisor. GIC will eventually set the right
+ * affinity for the irq and the 'unmask' will retarget the interrupt to that
+ * cpu.
+ */
+static int hv_pci_vec_irq_domain_activate(struct irq_domain *domain,
+					  struct irq_data *irqd, bool reserve)
+{
+	int cpu = cpumask_first(cpu_present_mask);
+
+	irq_data_update_effective_affinity(irqd, cpumask_of(cpu));
+
+	return 0;
+}
+
+static const struct irq_domain_ops hv_pci_domain_ops = {
+	.alloc	= hv_pci_vec_irq_domain_alloc,
+	.free	= hv_pci_vec_irq_domain_free,
+	.activate = hv_pci_vec_irq_domain_activate,
+};
+
+static int hv_pci_irqchip_init(void)
+{
+	static struct hv_pci_chip_data *chip_data;
+	struct fwnode_handle *fn = NULL;
+	int ret = -ENOMEM;
+
+	chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
+	if (!chip_data)
+		return ret;
+
+	mutex_init(&chip_data->map_lock);
+	fn = irq_domain_alloc_named_fwnode("hv_vpci_arm64");
+	if (!fn)
+		goto free_chip;
+
+	/*
+	 * IRQ domain once enabled, should not be removed since there is no
+	 * way to ensure that all the corresponding devices are also gone and
+	 * no interrupts will be generated.
+	 */
+	hv_msi_gic_irq_domain = acpi_irq_create_hierarchy(0, HV_PCI_MSI_SPI_NR,
+							  fn, &hv_pci_domain_ops,
+							  chip_data);
+
+	if (!hv_msi_gic_irq_domain) {
+		pr_err("Failed to create Hyper-V arm64 vPCI MSI IRQ domain\n");
+		goto free_chip;
+	}
+
+	return 0;
+
+free_chip:
+	kfree(chip_data);
+	if (fn)
+		irq_domain_free_fwnode(fn);
+
+	return ret;
+}
+
+static struct irq_domain *hv_pci_get_root_domain(void)
+{
+	return hv_msi_gic_irq_domain;
+}
+
+/*
+ * SPIs are used for interrupts of PCI devices and SPIs is managed via GICD
+ * registers which Hyper-V already supports, so no hypercall needed.
+ */
+static void hv_arch_irq_unmask(struct irq_data *data) { }
+#endif /* CONFIG_ARM64 */
+
+/**
+ * hv_pci_generic_compl() - Invoked for a completion packet
+ * @context:		Set up by the sender of the packet.
+ * @resp:		The response packet
+ * @resp_packet_size:	Size in bytes of the packet
+ *
+ * This function is used to trigger an event and report status
+ * for any message for which the completion packet contains a
+ * status and nothing else.
+ */
+static void hv_pci_generic_compl(void *context, struct pci_response *resp,
+				 int resp_packet_size)
+{
+	struct hv_pci_compl *comp_pkt = context;
+
+	comp_pkt->completion_status = resp->status;
+	complete(&comp_pkt->host_event);
+}
+
+static struct hv_pci_dev *get_pcichild_wslot(struct hv_pcibus_device *hbus,
+						u32 wslot);
+
+static void get_pcichild(struct hv_pci_dev *hpdev)
+{
+	refcount_inc(&hpdev->refs);
+}
+
+static void put_pcichild(struct hv_pci_dev *hpdev)
+{
+	if (refcount_dec_and_test(&hpdev->refs))
+		kfree(hpdev);
+}
+
+/*
+ * There is no good way to get notified from vmbus_onoffer_rescind(),
+ * so let's use polling here, since this is not a hot path.
+ */
+static int wait_for_response(struct hv_device *hdev,
+			     struct completion *comp)
+{
+	while (true) {
+		if (hdev->channel->rescind) {
+			dev_warn_once(&hdev->device, "The device is gone.\n");
+			return -ENODEV;
+		}
+
+		if (wait_for_completion_timeout(comp, HZ / 10))
+			break;
+	}
+
+	return 0;
+}
+
+/**
+ * devfn_to_wslot() - Convert from Linux PCI slot to Windows
+ * @devfn:	The Linux representation of PCI slot
+ *
+ * Windows uses a slightly different representation of PCI slot.
+ *
+ * Return: The Windows representation
+ */
+static u32 devfn_to_wslot(int devfn)
+{
+	union win_slot_encoding wslot;
+
+	wslot.slot = 0;
+	wslot.bits.dev = PCI_SLOT(devfn);
+	wslot.bits.func = PCI_FUNC(devfn);
+
+	return wslot.slot;
+}
+
+/**
+ * wslot_to_devfn() - Convert from Windows PCI slot to Linux
+ * @wslot:	The Windows representation of PCI slot
+ *
+ * Windows uses a slightly different representation of PCI slot.
+ *
+ * Return: The Linux representation
+ */
+static int wslot_to_devfn(u32 wslot)
+{
+	union win_slot_encoding slot_no;
+
+	slot_no.slot = wslot;
+	return PCI_DEVFN(slot_no.bits.dev, slot_no.bits.func);
+}
+
+static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32 *val)
+{
+	struct hv_mmio_read_input *in;
+	struct hv_mmio_read_output *out;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument page.  Use it for
+	 * both input and output.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	out = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*in);
+	in->gpa = gpa;
+	in->size = size;
+
+	ret = hv_do_hypercall(HVCALL_MMIO_READ, in, out);
+	if (hv_result_success(ret)) {
+		switch (size) {
+		case 1:
+			*val = *(u8 *)(out->data);
+			break;
+		case 2:
+			*val = *(u16 *)(out->data);
+			break;
+		default:
+			*val = *(u32 *)(out->data);
+			break;
+		}
+	} else
+		dev_err(dev, "MMIO read hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
+static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32 val)
+{
+	struct hv_mmio_write_input *in;
+	u64 ret;
+
+	/*
+	 * Must be called with interrupts disabled so it is safe
+	 * to use the per-cpu input argument memory.
+	 */
+	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	in->gpa = gpa;
+	in->size = size;
+	switch (size) {
+	case 1:
+		*(u8 *)(in->data) = val;
+		break;
+	case 2:
+		*(u16 *)(in->data) = val;
+		break;
+	default:
+		*(u32 *)(in->data) = val;
+		break;
+	}
+
+	ret = hv_do_hypercall(HVCALL_MMIO_WRITE, in, NULL);
+	if (!hv_result_success(ret))
+		dev_err(dev, "MMIO write hypercall error %llx addr %llx size %d\n",
+				ret, gpa, size);
+}
+
+/*
+ * PCI Configuration Space for these root PCI buses is implemented as a pair
+ * of pages in memory-mapped I/O space.  Writing to the first page chooses
+ * the PCI function being written or read.  Once the first page has been
+ * written to, the following page maps in the entire configuration space of
+ * the function.
+ */
+
+/**
+ * _hv_pcifront_read_config() - Internal PCI config read
+ * @hpdev:	The PCI driver's representation of the device
+ * @where:	Offset within config space
+ * @size:	Size of the transfer
+ * @val:	Pointer to the buffer receiving the data
+ */
+static void _hv_pcifront_read_config(struct hv_pci_dev *hpdev, int where,
+				     int size, u32 *val)
+{
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	int offset = where + CFG_PAGE_OFFSET;
+	unsigned long flags;
+
+	/*
+	 * If the attempt is to read the IDs or the ROM BAR, simulate that.
+	 */
+	if (where + size <= PCI_COMMAND) {
+		memcpy(val, ((u8 *)&hpdev->desc.v_id) + where, size);
+	} else if (where >= PCI_CLASS_REVISION && where + size <=
+		   PCI_CACHE_LINE_SIZE) {
+		memcpy(val, ((u8 *)&hpdev->desc.rev) + where -
+		       PCI_CLASS_REVISION, size);
+	} else if (where >= PCI_SUBSYSTEM_VENDOR_ID && where + size <=
+		   PCI_ROM_ADDRESS) {
+		memcpy(val, (u8 *)&hpdev->desc.subsystem_id + where -
+		       PCI_SUBSYSTEM_VENDOR_ID, size);
+	} else if (where >= PCI_ROM_ADDRESS && where + size <=
+		   PCI_CAPABILITY_LIST) {
+		/* ROM BARs are unimplemented */
+		*val = 0;
+	} else if (where >= PCI_INTERRUPT_LINE && where + size <=
+		   PCI_INTERRUPT_PIN) {
+		/*
+		 * Interrupt Line and Interrupt PIN are hard-wired to zero
+		 * because this front-end only supports message-signaled
+		 * interrupts.
+		 */
+		*val = 0;
+	} else if (where + size <= CFG_PAGE_SIZE) {
+
+		spin_lock_irqsave(&hbus->config_lock, flags);
+		if (hbus->use_calls) {
+			phys_addr_t addr = hbus->mem_config->start + offset;
+
+			hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+						hpdev->desc.win_slot.slot);
+			hv_pci_read_mmio(dev, addr, size, val);
+		} else {
+			void __iomem *addr = hbus->cfg_addr + offset;
+
+			/* Choose the function to be read. (See comment above) */
+			writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+			/* Make sure the function was chosen before reading. */
+			mb();
+			/* Read from that function's config space. */
+			switch (size) {
+			case 1:
+				*val = readb(addr);
+				break;
+			case 2:
+				*val = readw(addr);
+				break;
+			default:
+				*val = readl(addr);
+				break;
+			}
+			/*
+			 * Make sure the read was done before we release the
+			 * spinlock allowing consecutive reads/writes.
+			 */
+			mb();
+		}
+		spin_unlock_irqrestore(&hbus->config_lock, flags);
+	} else {
+		dev_err(dev, "Attempt to read beyond a function's config space.\n");
+	}
+}
+
+static u16 hv_pcifront_get_vendor_id(struct hv_pci_dev *hpdev)
+{
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	u32 val;
+	u16 ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hbus->config_lock, flags);
+
+	if (hbus->use_calls) {
+		phys_addr_t addr = hbus->mem_config->start +
+					 CFG_PAGE_OFFSET + PCI_VENDOR_ID;
+
+		hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+					hpdev->desc.win_slot.slot);
+		hv_pci_read_mmio(dev, addr, 2, &val);
+		ret = val;  /* Truncates to 16 bits */
+	} else {
+		void __iomem *addr = hbus->cfg_addr + CFG_PAGE_OFFSET +
+					     PCI_VENDOR_ID;
+		/* Choose the function to be read. (See comment above) */
+		writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+		/* Make sure the function was chosen before we start reading. */
+		mb();
+		/* Read from that function's config space. */
+		ret = readw(addr);
+		/*
+		 * mb() is not required here, because the
+		 * spin_unlock_irqrestore() is a barrier.
+		 */
+	}
+
+	spin_unlock_irqrestore(&hbus->config_lock, flags);
+
+	return ret;
+}
+
+/**
+ * _hv_pcifront_write_config() - Internal PCI config write
+ * @hpdev:	The PCI driver's representation of the device
+ * @where:	Offset within config space
+ * @size:	Size of the transfer
+ * @val:	The data being transferred
+ */
+static void _hv_pcifront_write_config(struct hv_pci_dev *hpdev, int where,
+				      int size, u32 val)
+{
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct device *dev = &hbus->hdev->device;
+	int offset = where + CFG_PAGE_OFFSET;
+	unsigned long flags;
+
+	if (where >= PCI_SUBSYSTEM_VENDOR_ID &&
+	    where + size <= PCI_CAPABILITY_LIST) {
+		/* SSIDs and ROM BARs are read-only */
+	} else if (where >= PCI_COMMAND && where + size <= CFG_PAGE_SIZE) {
+		spin_lock_irqsave(&hbus->config_lock, flags);
+
+		if (hbus->use_calls) {
+			phys_addr_t addr = hbus->mem_config->start + offset;
+
+			hv_pci_write_mmio(dev, hbus->mem_config->start, 4,
+						hpdev->desc.win_slot.slot);
+			hv_pci_write_mmio(dev, addr, size, val);
+		} else {
+			void __iomem *addr = hbus->cfg_addr + offset;
+
+			/* Choose the function to write. (See comment above) */
+			writel(hpdev->desc.win_slot.slot, hbus->cfg_addr);
+			/* Make sure the function was chosen before writing. */
+			wmb();
+			/* Write to that function's config space. */
+			switch (size) {
+			case 1:
+				writeb(val, addr);
+				break;
+			case 2:
+				writew(val, addr);
+				break;
+			default:
+				writel(val, addr);
+				break;
+			}
+			/*
+			 * Make sure the write was done before we release the
+			 * spinlock allowing consecutive reads/writes.
+			 */
+			mb();
+		}
+		spin_unlock_irqrestore(&hbus->config_lock, flags);
+	} else {
+		dev_err(dev, "Attempt to write beyond a function's config space.\n");
+	}
+}
+
+/**
+ * hv_pcifront_read_config() - Read configuration space
+ * @bus: PCI Bus structure
+ * @devfn: Device/function
+ * @where: Offset from base
+ * @size: Byte/word/dword
+ * @val: Value to be read
+ *
+ * Return: PCIBIOS_SUCCESSFUL on success
+ *	   PCIBIOS_DEVICE_NOT_FOUND on failure
+ */
+static int hv_pcifront_read_config(struct pci_bus *bus, unsigned int devfn,
+				   int where, int size, u32 *val)
+{
+	struct hv_pcibus_device *hbus =
+		container_of(bus->sysdata, struct hv_pcibus_device, sysdata);
+	struct hv_pci_dev *hpdev;
+
+	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(devfn));
+	if (!hpdev)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	_hv_pcifront_read_config(hpdev, where, size, val);
+
+	put_pcichild(hpdev);
+	return PCIBIOS_SUCCESSFUL;
+}
+
+/**
+ * hv_pcifront_write_config() - Write configuration space
+ * @bus: PCI Bus structure
+ * @devfn: Device/function
+ * @where: Offset from base
+ * @size: Byte/word/dword
+ * @val: Value to be written to device
+ *
+ * Return: PCIBIOS_SUCCESSFUL on success
+ *	   PCIBIOS_DEVICE_NOT_FOUND on failure
+ */
+static int hv_pcifront_write_config(struct pci_bus *bus, unsigned int devfn,
+				    int where, int size, u32 val)
+{
+	struct hv_pcibus_device *hbus =
+	    container_of(bus->sysdata, struct hv_pcibus_device, sysdata);
+	struct hv_pci_dev *hpdev;
+
+	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(devfn));
+	if (!hpdev)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	_hv_pcifront_write_config(hpdev, where, size, val);
+
+	put_pcichild(hpdev);
+	return PCIBIOS_SUCCESSFUL;
+}
+
+/* PCIe operations */
+static struct pci_ops hv_pcifront_ops = {
+	.read  = hv_pcifront_read_config,
+	.write = hv_pcifront_write_config,
+};
+
+/*
+ * Paravirtual backchannel
+ *
+ * Hyper-V SR-IOV provides a backchannel mechanism in software for
+ * communication between a VF driver and a PF driver.  These
+ * "configuration blocks" are similar in concept to PCI configuration space,
+ * but instead of doing reads and writes in 32-bit chunks through a very slow
+ * path, packets of up to 128 bytes can be sent or received asynchronously.
+ *
+ * Nearly every SR-IOV device contains just such a communications channel in
+ * hardware, so using this one in software is usually optional.  Using the
+ * software channel, however, allows driver implementers to leverage software
+ * tools that fuzz the communications channel looking for vulnerabilities.
+ *
+ * The usage model for these packets puts the responsibility for reading or
+ * writing on the VF driver.  The VF driver sends a read or a write packet,
+ * indicating which "block" is being referred to by number.
+ *
+ * If the PF driver wishes to initiate communication, it can "invalidate" one or
+ * more of the first 64 blocks.  This invalidation is delivered via a callback
+ * supplied by the VF driver by this driver.
+ *
+ * No protocol is implied, except that supplied by the PF and VF drivers.
+ */
+
+struct hv_read_config_compl {
+	struct hv_pci_compl comp_pkt;
+	void *buf;
+	unsigned int len;
+	unsigned int bytes_returned;
+};
+
+/**
+ * hv_pci_read_config_compl() - Invoked when a response packet
+ * for a read config block operation arrives.
+ * @context:		Identifies the read config operation
+ * @resp:		The response packet itself
+ * @resp_packet_size:	Size in bytes of the response packet
+ */
+static void hv_pci_read_config_compl(void *context, struct pci_response *resp,
+				     int resp_packet_size)
+{
+	struct hv_read_config_compl *comp = context;
+	struct pci_read_block_response *read_resp =
+		(struct pci_read_block_response *)resp;
+	unsigned int data_len, hdr_len;
+
+	hdr_len = offsetof(struct pci_read_block_response, bytes);
+	if (resp_packet_size < hdr_len) {
+		comp->comp_pkt.completion_status = -1;
+		goto out;
+	}
+
+	data_len = resp_packet_size - hdr_len;
+	if (data_len > 0 && read_resp->status == 0) {
+		comp->bytes_returned = min(comp->len, data_len);
+		memcpy(comp->buf, read_resp->bytes, comp->bytes_returned);
+	} else {
+		comp->bytes_returned = 0;
+	}
+
+	comp->comp_pkt.completion_status = read_resp->status;
+out:
+	complete(&comp->comp_pkt.host_event);
+}
+
+/**
+ * hv_read_config_block() - Sends a read config block request to
+ * the back-end driver running in the Hyper-V parent partition.
+ * @pdev:		The PCI driver's representation for this device.
+ * @buf:		Buffer into which the config block will be copied.
+ * @len:		Size in bytes of buf.
+ * @block_id:		Identifies the config block which has been requested.
+ * @bytes_returned:	Size which came back from the back-end driver.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_read_config_block(struct pci_dev *pdev, void *buf,
+				unsigned int len, unsigned int block_id,
+				unsigned int *bytes_returned)
+{
+	struct hv_pcibus_device *hbus =
+		container_of(pdev->bus->sysdata, struct hv_pcibus_device,
+			     sysdata);
+	struct {
+		struct pci_packet pkt;
+		char buf[sizeof(struct pci_read_block)];
+	} pkt;
+	struct hv_read_config_compl comp_pkt;
+	struct pci_read_block *read_blk;
+	int ret;
+
+	if (len == 0 || len > HV_CONFIG_BLOCK_SIZE_MAX)
+		return -EINVAL;
+
+	init_completion(&comp_pkt.comp_pkt.host_event);
+	comp_pkt.buf = buf;
+	comp_pkt.len = len;
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.pkt.completion_func = hv_pci_read_config_compl;
+	pkt.pkt.compl_ctxt = &comp_pkt;
+	read_blk = (struct pci_read_block *)&pkt.pkt.message;
+	read_blk->message_type.type = PCI_READ_BLOCK;
+	read_blk->wslot.slot = devfn_to_wslot(pdev->devfn);
+	read_blk->block_id = block_id;
+	read_blk->bytes_requested = len;
+
+	ret = vmbus_sendpacket(hbus->hdev->channel, read_blk,
+			       sizeof(*read_blk), (unsigned long)&pkt.pkt,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret)
+		return ret;
+
+	ret = wait_for_response(hbus->hdev, &comp_pkt.comp_pkt.host_event);
+	if (ret)
+		return ret;
+
+	if (comp_pkt.comp_pkt.completion_status != 0 ||
+	    comp_pkt.bytes_returned == 0) {
+		dev_err(&hbus->hdev->device,
+			"Read Config Block failed: 0x%x, bytes_returned=%d\n",
+			comp_pkt.comp_pkt.completion_status,
+			comp_pkt.bytes_returned);
+		return -EIO;
+	}
+
+	*bytes_returned = comp_pkt.bytes_returned;
+	return 0;
+}
+
+/**
+ * hv_pci_write_config_compl() - Invoked when a response packet for a write
+ * config block operation arrives.
+ * @context:		Identifies the write config operation
+ * @resp:		The response packet itself
+ * @resp_packet_size:	Size in bytes of the response packet
+ */
+static void hv_pci_write_config_compl(void *context, struct pci_response *resp,
+				      int resp_packet_size)
+{
+	struct hv_pci_compl *comp_pkt = context;
+
+	comp_pkt->completion_status = resp->status;
+	complete(&comp_pkt->host_event);
+}
+
+/**
+ * hv_write_config_block() - Sends a write config block request to the
+ * back-end driver running in the Hyper-V parent partition.
+ * @pdev:		The PCI driver's representation for this device.
+ * @buf:		Buffer from which the config block will	be copied.
+ * @len:		Size in bytes of buf.
+ * @block_id:		Identifies the config block which is being written.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_write_config_block(struct pci_dev *pdev, void *buf,
+				unsigned int len, unsigned int block_id)
+{
+	struct hv_pcibus_device *hbus =
+		container_of(pdev->bus->sysdata, struct hv_pcibus_device,
+			     sysdata);
+	struct {
+		struct pci_packet pkt;
+		char buf[sizeof(struct pci_write_block)];
+		u32 reserved;
+	} pkt;
+	struct hv_pci_compl comp_pkt;
+	struct pci_write_block *write_blk;
+	u32 pkt_size;
+	int ret;
+
+	if (len == 0 || len > HV_CONFIG_BLOCK_SIZE_MAX)
+		return -EINVAL;
+
+	init_completion(&comp_pkt.host_event);
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.pkt.completion_func = hv_pci_write_config_compl;
+	pkt.pkt.compl_ctxt = &comp_pkt;
+	write_blk = (struct pci_write_block *)&pkt.pkt.message;
+	write_blk->message_type.type = PCI_WRITE_BLOCK;
+	write_blk->wslot.slot = devfn_to_wslot(pdev->devfn);
+	write_blk->block_id = block_id;
+	write_blk->byte_count = len;
+	memcpy(write_blk->bytes, buf, len);
+	pkt_size = offsetof(struct pci_write_block, bytes) + len;
+	/*
+	 * This quirk is required on some hosts shipped around 2018, because
+	 * these hosts don't check the pkt_size correctly (new hosts have been
+	 * fixed since early 2019). The quirk is also safe on very old hosts
+	 * and new hosts, because, on them, what really matters is the length
+	 * specified in write_blk->byte_count.
+	 */
+	pkt_size += sizeof(pkt.reserved);
+
+	ret = vmbus_sendpacket(hbus->hdev->channel, write_blk, pkt_size,
+			       (unsigned long)&pkt.pkt, VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret)
+		return ret;
+
+	ret = wait_for_response(hbus->hdev, &comp_pkt.host_event);
+	if (ret)
+		return ret;
+
+	if (comp_pkt.completion_status != 0) {
+		dev_err(&hbus->hdev->device,
+			"Write Config Block failed: 0x%x\n",
+			comp_pkt.completion_status);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * hv_register_block_invalidate() - Invoked when a config block invalidation
+ * arrives from the back-end driver.
+ * @pdev:		The PCI driver's representation for this device.
+ * @context:		Identifies the device.
+ * @block_invalidate:	Identifies all of the blocks being invalidated.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_register_block_invalidate(struct pci_dev *pdev, void *context,
+					void (*block_invalidate)(void *context,
+								 u64 block_mask))
+{
+	struct hv_pcibus_device *hbus =
+		container_of(pdev->bus->sysdata, struct hv_pcibus_device,
+			     sysdata);
+	struct hv_pci_dev *hpdev;
+
+	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
+	if (!hpdev)
+		return -ENODEV;
+
+	hpdev->block_invalidate = block_invalidate;
+	hpdev->invalidate_context = context;
+
+	put_pcichild(hpdev);
+	return 0;
+
+}
+
+/* Interrupt management hooks */
+static void hv_int_desc_free(struct hv_pci_dev *hpdev,
+			     struct tran_int_desc *int_desc)
+{
+	struct pci_delete_interrupt *int_pkt;
+	struct {
+		struct pci_packet pkt;
+		u8 buffer[sizeof(struct pci_delete_interrupt)];
+	} ctxt;
+
+	if (!int_desc->vector_count) {
+		kfree(int_desc);
+		return;
+	}
+	memset(&ctxt, 0, sizeof(ctxt));
+	int_pkt = (struct pci_delete_interrupt *)&ctxt.pkt.message;
+	int_pkt->message_type.type =
+		PCI_DELETE_INTERRUPT_MESSAGE;
+	int_pkt->wslot.slot = hpdev->desc.win_slot.slot;
+	int_pkt->int_desc = *int_desc;
+	vmbus_sendpacket(hpdev->hbus->hdev->channel, int_pkt, sizeof(*int_pkt),
+			 0, VM_PKT_DATA_INBAND, 0);
+	kfree(int_desc);
+}
+
+/**
+ * hv_msi_free() - Free the MSI.
+ * @domain:	The interrupt domain pointer
+ * @info:	Extra MSI-related context
+ * @irq:	Identifies the IRQ.
+ *
+ * The Hyper-V parent partition and hypervisor are tracking the
+ * messages that are in use, keeping the interrupt redirection
+ * table up to date.  This callback sends a message that frees
+ * the IRT entry and related tracking nonsense.
+ */
+static void hv_msi_free(struct irq_domain *domain, struct msi_domain_info *info,
+			unsigned int irq)
+{
+	struct hv_pcibus_device *hbus;
+	struct hv_pci_dev *hpdev;
+	struct pci_dev *pdev;
+	struct tran_int_desc *int_desc;
+	struct irq_data *irq_data = irq_domain_get_irq_data(domain, irq);
+	struct msi_desc *msi = irq_data_get_msi_desc(irq_data);
+
+	pdev = msi_desc_to_pci_dev(msi);
+	hbus = info->data;
+	int_desc = irq_data_get_irq_chip_data(irq_data);
+	if (!int_desc)
+		return;
+
+	irq_data->chip_data = NULL;
+	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
+	if (!hpdev) {
+		kfree(int_desc);
+		return;
+	}
+
+	hv_int_desc_free(hpdev, int_desc);
+	put_pcichild(hpdev);
+}
+
+static void hv_irq_mask(struct irq_data *data)
+{
+	pci_msi_mask_irq(data);
+	if (data->parent_data->chip->irq_mask)
+		irq_chip_mask_parent(data);
+}
+
+static void hv_irq_unmask(struct irq_data *data)
+{
+	hv_arch_irq_unmask(data);
+
+	if (data->parent_data->chip->irq_unmask)
+		irq_chip_unmask_parent(data);
+	pci_msi_unmask_irq(data);
+}
+
+struct compose_comp_ctxt {
+	struct hv_pci_compl comp_pkt;
+	struct tran_int_desc int_desc;
+};
+
+static void hv_pci_compose_compl(void *context, struct pci_response *resp,
+				 int resp_packet_size)
+{
+	struct compose_comp_ctxt *comp_pkt = context;
+	struct pci_create_int_response *int_resp =
+		(struct pci_create_int_response *)resp;
+
+	if (resp_packet_size < sizeof(*int_resp)) {
+		comp_pkt->comp_pkt.completion_status = -1;
+		goto out;
+	}
+	comp_pkt->comp_pkt.completion_status = resp->status;
+	comp_pkt->int_desc = int_resp->int_desc;
+out:
+	complete(&comp_pkt->comp_pkt.host_event);
+}
+
+static u32 hv_compose_msi_req_v1(
+	struct pci_create_interrupt *int_pkt,
+	u32 slot, u8 vector, u16 vector_count)
+{
+	int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE;
+	int_pkt->wslot.slot = slot;
+	int_pkt->int_desc.vector = vector;
+	int_pkt->int_desc.vector_count = vector_count;
+	int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
+
+	/*
+	 * Create MSI w/ dummy vCPU set, overwritten by subsequent retarget in
+	 * hv_irq_unmask().
+	 */
+	int_pkt->int_desc.cpu_mask = CPU_AFFINITY_ALL;
+
+	return sizeof(*int_pkt);
+}
+
+/*
+ * The vCPU selected by hv_compose_multi_msi_req_get_cpu() and
+ * hv_compose_msi_req_get_cpu() is a "dummy" vCPU because the final vCPU to be
+ * interrupted is specified later in hv_irq_unmask() and communicated to Hyper-V
+ * via the HVCALL_RETARGET_INTERRUPT hypercall. But the choice of dummy vCPU is
+ * not irrelevant because Hyper-V chooses the physical CPU to handle the
+ * interrupts based on the vCPU specified in message sent to the vPCI VSP in
+ * hv_compose_msi_msg(). Hyper-V's choice of pCPU is not visible to the guest,
+ * but assigning too many vPCI device interrupts to the same pCPU can cause a
+ * performance bottleneck. So we spread out the dummy vCPUs to influence Hyper-V
+ * to spread out the pCPUs that it selects.
+ *
+ * For the single-MSI and MSI-X cases, it's OK for hv_compose_msi_req_get_cpu()
+ * to always return the same dummy vCPU, because a second call to
+ * hv_compose_msi_msg() contains the "real" vCPU, causing Hyper-V to choose a
+ * new pCPU for the interrupt. But for the multi-MSI case, the second call to
+ * hv_compose_msi_msg() exits without sending a message to the vPCI VSP, so the
+ * original dummy vCPU is used. This dummy vCPU must be round-robin'ed so that
+ * the pCPUs are spread out. All interrupts for a multi-MSI device end up using
+ * the same pCPU, even though the vCPUs will be spread out by later calls
+ * to hv_irq_unmask(), but that is the best we can do now.
+ *
+ * With Hyper-V in Nov 2022, the HVCALL_RETARGET_INTERRUPT hypercall does *not*
+ * cause Hyper-V to reselect the pCPU based on the specified vCPU. Such an
+ * enhancement is planned for a future version. With that enhancement, the
+ * dummy vCPU selection won't matter, and interrupts for the same multi-MSI
+ * device will be spread across multiple pCPUs.
+ */
+
+/*
+ * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten
+ * by subsequent retarget in hv_irq_unmask().
+ */
+static int hv_compose_msi_req_get_cpu(const struct cpumask *affinity)
+{
+	return cpumask_first_and(affinity, cpu_online_mask);
+}
+
+/*
+ * Make sure the dummy vCPU values for multi-MSI don't all point to vCPU0.
+ */
+static int hv_compose_multi_msi_req_get_cpu(void)
+{
+	static DEFINE_SPINLOCK(multi_msi_cpu_lock);
+
+	/* -1 means starting with CPU 0 */
+	static int cpu_next = -1;
+
+	unsigned long flags;
+	int cpu;
+
+	spin_lock_irqsave(&multi_msi_cpu_lock, flags);
+
+	cpu_next = cpumask_next_wrap(cpu_next, cpu_online_mask, nr_cpu_ids,
+				     false);
+	cpu = cpu_next;
+
+	spin_unlock_irqrestore(&multi_msi_cpu_lock, flags);
+
+	return cpu;
+}
+
+static u32 hv_compose_msi_req_v2(
+	struct pci_create_interrupt2 *int_pkt, int cpu,
+	u32 slot, u8 vector, u16 vector_count)
+{
+	int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE2;
+	int_pkt->wslot.slot = slot;
+	int_pkt->int_desc.vector = vector;
+	int_pkt->int_desc.vector_count = vector_count;
+	int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
+	int_pkt->int_desc.processor_array[0] =
+		hv_cpu_number_to_vp_number(cpu);
+	int_pkt->int_desc.processor_count = 1;
+
+	return sizeof(*int_pkt);
+}
+
+static u32 hv_compose_msi_req_v3(
+	struct pci_create_interrupt3 *int_pkt, int cpu,
+	u32 slot, u32 vector, u16 vector_count)
+{
+	int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE3;
+	int_pkt->wslot.slot = slot;
+	int_pkt->int_desc.vector = vector;
+	int_pkt->int_desc.reserved = 0;
+	int_pkt->int_desc.vector_count = vector_count;
+	int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
+	int_pkt->int_desc.processor_array[0] =
+		hv_cpu_number_to_vp_number(cpu);
+	int_pkt->int_desc.processor_count = 1;
+
+	return sizeof(*int_pkt);
+}
+
+/**
+ * hv_compose_msi_msg() - Supplies a valid MSI address/data
+ * @data:	Everything about this MSI
+ * @msg:	Buffer that is filled in by this function
+ *
+ * This function unpacks the IRQ looking for target CPU set, IDT
+ * vector and mode and sends a message to the parent partition
+ * asking for a mapping for that tuple in this partition.  The
+ * response supplies a data value and address to which that data
+ * should be written to trigger that interrupt.
+ */
+static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
+{
+	struct hv_pcibus_device *hbus;
+	struct vmbus_channel *channel;
+	struct hv_pci_dev *hpdev;
+	struct pci_bus *pbus;
+	struct pci_dev *pdev;
+	const struct cpumask *dest;
+	struct compose_comp_ctxt comp;
+	struct tran_int_desc *int_desc;
+	struct msi_desc *msi_desc;
+	/*
+	 * vector_count should be u16: see hv_msi_desc, hv_msi_desc2
+	 * and hv_msi_desc3. vector must be u32: see hv_msi_desc3.
+	 */
+	u16 vector_count;
+	u32 vector;
+	struct {
+		struct pci_packet pci_pkt;
+		union {
+			struct pci_create_interrupt v1;
+			struct pci_create_interrupt2 v2;
+			struct pci_create_interrupt3 v3;
+		} int_pkts;
+	} __packed ctxt;
+	bool multi_msi;
+	u64 trans_id;
+	u32 size;
+	int ret;
+	int cpu;
+
+	msi_desc  = irq_data_get_msi_desc(data);
+	multi_msi = !msi_desc->pci.msi_attrib.is_msix &&
+		    msi_desc->nvec_used > 1;
+
+	/* Reuse the previous allocation */
+	if (data->chip_data && multi_msi) {
+		int_desc = data->chip_data;
+		msg->address_hi = int_desc->address >> 32;
+		msg->address_lo = int_desc->address & 0xffffffff;
+		msg->data = int_desc->data;
+		return;
+	}
+
+	pdev = msi_desc_to_pci_dev(msi_desc);
+	dest = irq_data_get_effective_affinity_mask(data);
+	pbus = pdev->bus;
+	hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
+	channel = hbus->hdev->channel;
+	hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
+	if (!hpdev)
+		goto return_null_message;
+
+	/* Free any previous message that might have already been composed. */
+	if (data->chip_data && !multi_msi) {
+		int_desc = data->chip_data;
+		data->chip_data = NULL;
+		hv_int_desc_free(hpdev, int_desc);
+	}
+
+	int_desc = kzalloc(sizeof(*int_desc), GFP_ATOMIC);
+	if (!int_desc)
+		goto drop_reference;
+
+	if (multi_msi) {
+		/*
+		 * If this is not the first MSI of Multi MSI, we already have
+		 * a mapping.  Can exit early.
+		 */
+		if (msi_desc->irq != data->irq) {
+			data->chip_data = int_desc;
+			int_desc->address = msi_desc->msg.address_lo |
+					    (u64)msi_desc->msg.address_hi << 32;
+			int_desc->data = msi_desc->msg.data +
+					 (data->irq - msi_desc->irq);
+			msg->address_hi = msi_desc->msg.address_hi;
+			msg->address_lo = msi_desc->msg.address_lo;
+			msg->data = int_desc->data;
+			put_pcichild(hpdev);
+			return;
+		}
+		/*
+		 * The vector we select here is a dummy value.  The correct
+		 * value gets sent to the hypervisor in unmask().  This needs
+		 * to be aligned with the count, and also not zero.  Multi-msi
+		 * is powers of 2 up to 32, so 32 will always work here.
+		 */
+		vector = 32;
+		vector_count = msi_desc->nvec_used;
+		cpu = hv_compose_multi_msi_req_get_cpu();
+	} else {
+		vector = hv_msi_get_int_vector(data);
+		vector_count = 1;
+		cpu = hv_compose_msi_req_get_cpu(dest);
+	}
+
+	/*
+	 * hv_compose_msi_req_v1 and v2 are for x86 only, meaning 'vector'
+	 * can't exceed u8. Cast 'vector' down to u8 for v1/v2 explicitly
+	 * for better readability.
+	 */
+	memset(&ctxt, 0, sizeof(ctxt));
+	init_completion(&comp.comp_pkt.host_event);
+	ctxt.pci_pkt.completion_func = hv_pci_compose_compl;
+	ctxt.pci_pkt.compl_ctxt = &comp;
+
+	switch (hbus->protocol_version) {
+	case PCI_PROTOCOL_VERSION_1_1:
+		size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
+					hpdev->desc.win_slot.slot,
+					(u8)vector,
+					vector_count);
+		break;
+
+	case PCI_PROTOCOL_VERSION_1_2:
+	case PCI_PROTOCOL_VERSION_1_3:
+		size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
+					cpu,
+					hpdev->desc.win_slot.slot,
+					(u8)vector,
+					vector_count);
+		break;
+
+	case PCI_PROTOCOL_VERSION_1_4:
+		size = hv_compose_msi_req_v3(&ctxt.int_pkts.v3,
+					cpu,
+					hpdev->desc.win_slot.slot,
+					vector,
+					vector_count);
+		break;
+
+	default:
+		/* As we only negotiate protocol versions known to this driver,
+		 * this path should never hit. However, this is it not a hot
+		 * path so we print a message to aid future updates.
+		 */
+		dev_err(&hbus->hdev->device,
+			"Unexpected vPCI protocol, update driver.");
+		goto free_int_desc;
+	}
+
+	ret = vmbus_sendpacket_getid(hpdev->hbus->hdev->channel, &ctxt.int_pkts,
+				     size, (unsigned long)&ctxt.pci_pkt,
+				     &trans_id, VM_PKT_DATA_INBAND,
+				     VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret) {
+		dev_err(&hbus->hdev->device,
+			"Sending request for interrupt failed: 0x%x",
+			comp.comp_pkt.completion_status);
+		goto free_int_desc;
+	}
+
+	/*
+	 * Prevents hv_pci_onchannelcallback() from running concurrently
+	 * in the tasklet.
+	 */
+	tasklet_disable_in_atomic(&channel->callback_event);
+
+	/*
+	 * Since this function is called with IRQ locks held, can't
+	 * do normal wait for completion; instead poll.
+	 */
+	while (!try_wait_for_completion(&comp.comp_pkt.host_event)) {
+		unsigned long flags;
+
+		/* 0xFFFF means an invalid PCI VENDOR ID. */
+		if (hv_pcifront_get_vendor_id(hpdev) == 0xFFFF) {
+			dev_err_once(&hbus->hdev->device,
+				     "the device has gone\n");
+			goto enable_tasklet;
+		}
+
+		/*
+		 * Make sure that the ring buffer data structure doesn't get
+		 * freed while we dereference the ring buffer pointer.  Test
+		 * for the channel's onchannel_callback being NULL within a
+		 * sched_lock critical section.  See also the inline comments
+		 * in vmbus_reset_channel_cb().
+		 */
+		spin_lock_irqsave(&channel->sched_lock, flags);
+		if (unlikely(channel->onchannel_callback == NULL)) {
+			spin_unlock_irqrestore(&channel->sched_lock, flags);
+			goto enable_tasklet;
+		}
+		hv_pci_onchannelcallback(hbus);
+		spin_unlock_irqrestore(&channel->sched_lock, flags);
+
+		udelay(100);
+	}
+
+	tasklet_enable(&channel->callback_event);
+
+	if (comp.comp_pkt.completion_status < 0) {
+		dev_err(&hbus->hdev->device,
+			"Request for interrupt failed: 0x%x",
+			comp.comp_pkt.completion_status);
+		goto free_int_desc;
+	}
+
+	/*
+	 * Record the assignment so that this can be unwound later. Using
+	 * irq_set_chip_data() here would be appropriate, but the lock it takes
+	 * is already held.
+	 */
+	*int_desc = comp.int_desc;
+	data->chip_data = int_desc;
+
+	/* Pass up the result. */
+	msg->address_hi = comp.int_desc.address >> 32;
+	msg->address_lo = comp.int_desc.address & 0xffffffff;
+	msg->data = comp.int_desc.data;
+
+	put_pcichild(hpdev);
+	return;
+
+enable_tasklet:
+	tasklet_enable(&channel->callback_event);
+	/*
+	 * The completion packet on the stack becomes invalid after 'return';
+	 * remove the ID from the VMbus requestor if the identifier is still
+	 * mapped to/associated with the packet.  (The identifier could have
+	 * been 're-used', i.e., already removed and (re-)mapped.)
+	 *
+	 * Cf. hv_pci_onchannelcallback().
+	 */
+	vmbus_request_addr_match(channel, trans_id, (unsigned long)&ctxt.pci_pkt);
+free_int_desc:
+	kfree(int_desc);
+drop_reference:
+	put_pcichild(hpdev);
+return_null_message:
+	msg->address_hi = 0;
+	msg->address_lo = 0;
+	msg->data = 0;
+}
+
+/* HW Interrupt Chip Descriptor */
+static struct irq_chip hv_msi_irq_chip = {
+	.name			= "Hyper-V PCIe MSI",
+	.irq_compose_msi_msg	= hv_compose_msi_msg,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+#ifdef CONFIG_X86
+	.irq_ack		= irq_chip_ack_parent,
+#elif defined(CONFIG_ARM64)
+	.irq_eoi		= irq_chip_eoi_parent,
+#endif
+	.irq_mask		= hv_irq_mask,
+	.irq_unmask		= hv_irq_unmask,
+};
+
+static struct msi_domain_ops hv_msi_ops = {
+	.msi_prepare	= hv_msi_prepare,
+	.msi_free	= hv_msi_free,
+};
+
+/**
+ * hv_pcie_init_irq_domain() - Initialize IRQ domain
+ * @hbus:	The root PCI bus
+ *
+ * This function creates an IRQ domain which will be used for
+ * interrupts from devices that have been passed through.  These
+ * devices only support MSI and MSI-X, not line-based interrupts
+ * or simulations of line-based interrupts through PCIe's
+ * fabric-layer messages.  Because interrupts are remapped, we
+ * can support multi-message MSI here.
+ *
+ * Return: '0' on success and error value on failure
+ */
+static int hv_pcie_init_irq_domain(struct hv_pcibus_device *hbus)
+{
+	hbus->msi_info.chip = &hv_msi_irq_chip;
+	hbus->msi_info.ops = &hv_msi_ops;
+	hbus->msi_info.flags = (MSI_FLAG_USE_DEF_DOM_OPS |
+		MSI_FLAG_USE_DEF_CHIP_OPS | MSI_FLAG_MULTI_PCI_MSI |
+		MSI_FLAG_PCI_MSIX);
+	hbus->msi_info.handler = FLOW_HANDLER;
+	hbus->msi_info.handler_name = FLOW_NAME;
+	hbus->msi_info.data = hbus;
+	hbus->irq_domain = pci_msi_create_irq_domain(hbus->fwnode,
+						     &hbus->msi_info,
+						     hv_pci_get_root_domain());
+	if (!hbus->irq_domain) {
+		dev_err(&hbus->hdev->device,
+			"Failed to build an MSI IRQ domain\n");
+		return -ENODEV;
+	}
+
+	dev_set_msi_domain(&hbus->bridge->dev, hbus->irq_domain);
+
+	return 0;
+}
+
+/**
+ * get_bar_size() - Get the address space consumed by a BAR
+ * @bar_val:	Value that a BAR returned after -1 was written
+ *              to it.
+ *
+ * This function returns the size of the BAR, rounded up to 1
+ * page.  It has to be rounded up because the hypervisor's page
+ * table entry that maps the BAR into the VM can't specify an
+ * offset within a page.  The invariant is that the hypervisor
+ * must place any BARs of smaller than page length at the
+ * beginning of a page.
+ *
+ * Return:	Size in bytes of the consumed MMIO space.
+ */
+static u64 get_bar_size(u64 bar_val)
+{
+	return round_up((1 + ~(bar_val & PCI_BASE_ADDRESS_MEM_MASK)),
+			PAGE_SIZE);
+}
+
+/**
+ * survey_child_resources() - Total all MMIO requirements
+ * @hbus:	Root PCI bus, as understood by this driver
+ */
+static void survey_child_resources(struct hv_pcibus_device *hbus)
+{
+	struct hv_pci_dev *hpdev;
+	resource_size_t bar_size = 0;
+	unsigned long flags;
+	struct completion *event;
+	u64 bar_val;
+	int i;
+
+	/* If nobody is waiting on the answer, don't compute it. */
+	event = xchg(&hbus->survey_event, NULL);
+	if (!event)
+		return;
+
+	/* If the answer has already been computed, go with it. */
+	if (hbus->low_mmio_space || hbus->high_mmio_space) {
+		complete(event);
+		return;
+	}
+
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+
+	/*
+	 * Due to an interesting quirk of the PCI spec, all memory regions
+	 * for a child device are a power of 2 in size and aligned in memory,
+	 * so it's sufficient to just add them up without tracking alignment.
+	 */
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+			if (hpdev->probed_bar[i] & PCI_BASE_ADDRESS_SPACE_IO)
+				dev_err(&hbus->hdev->device,
+					"There's an I/O BAR in this list!\n");
+
+			if (hpdev->probed_bar[i] != 0) {
+				/*
+				 * A probed BAR has all the upper bits set that
+				 * can be changed.
+				 */
+
+				bar_val = hpdev->probed_bar[i];
+				if (bar_val & PCI_BASE_ADDRESS_MEM_TYPE_64)
+					bar_val |=
+					((u64)hpdev->probed_bar[++i] << 32);
+				else
+					bar_val |= 0xffffffff00000000ULL;
+
+				bar_size = get_bar_size(bar_val);
+
+				if (bar_val & PCI_BASE_ADDRESS_MEM_TYPE_64)
+					hbus->high_mmio_space += bar_size;
+				else
+					hbus->low_mmio_space += bar_size;
+			}
+		}
+	}
+
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+	complete(event);
+}
+
+/**
+ * prepopulate_bars() - Fill in BARs with defaults
+ * @hbus:	Root PCI bus, as understood by this driver
+ *
+ * The core PCI driver code seems much, much happier if the BARs
+ * for a device have values upon first scan. So fill them in.
+ * The algorithm below works down from large sizes to small,
+ * attempting to pack the assignments optimally. The assumption,
+ * enforced in other parts of the code, is that the beginning of
+ * the memory-mapped I/O space will be aligned on the largest
+ * BAR size.
+ */
+static void prepopulate_bars(struct hv_pcibus_device *hbus)
+{
+	resource_size_t high_size = 0;
+	resource_size_t low_size = 0;
+	resource_size_t high_base = 0;
+	resource_size_t low_base = 0;
+	resource_size_t bar_size;
+	struct hv_pci_dev *hpdev;
+	unsigned long flags;
+	u64 bar_val;
+	u32 command;
+	bool high;
+	int i;
+
+	if (hbus->low_mmio_space) {
+		low_size = 1ULL << (63 - __builtin_clzll(hbus->low_mmio_space));
+		low_base = hbus->low_mmio_res->start;
+	}
+
+	if (hbus->high_mmio_space) {
+		high_size = 1ULL <<
+			(63 - __builtin_clzll(hbus->high_mmio_space));
+		high_base = hbus->high_mmio_res->start;
+	}
+
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+
+	/*
+	 * Clear the memory enable bit, in case it's already set. This occurs
+	 * in the suspend path of hibernation, where the device is suspended,
+	 * resumed and suspended again: see hibernation_snapshot() and
+	 * hibernation_platform_enter().
+	 *
+	 * If the memory enable bit is already set, Hyper-V silently ignores
+	 * the below BAR updates, and the related PCI device driver can not
+	 * work, because reading from the device register(s) always returns
+	 * 0xFFFFFFFF (PCI_ERROR_RESPONSE).
+	 */
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		_hv_pcifront_read_config(hpdev, PCI_COMMAND, 2, &command);
+		command &= ~PCI_COMMAND_MEMORY;
+		_hv_pcifront_write_config(hpdev, PCI_COMMAND, 2, command);
+	}
+
+	/* Pick addresses for the BARs. */
+	do {
+		list_for_each_entry(hpdev, &hbus->children, list_entry) {
+			for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+				bar_val = hpdev->probed_bar[i];
+				if (bar_val == 0)
+					continue;
+				high = bar_val & PCI_BASE_ADDRESS_MEM_TYPE_64;
+				if (high) {
+					bar_val |=
+						((u64)hpdev->probed_bar[i + 1]
+						 << 32);
+				} else {
+					bar_val |= 0xffffffffULL << 32;
+				}
+				bar_size = get_bar_size(bar_val);
+				if (high) {
+					if (high_size != bar_size) {
+						i++;
+						continue;
+					}
+					_hv_pcifront_write_config(hpdev,
+						PCI_BASE_ADDRESS_0 + (4 * i),
+						4,
+						(u32)(high_base & 0xffffff00));
+					i++;
+					_hv_pcifront_write_config(hpdev,
+						PCI_BASE_ADDRESS_0 + (4 * i),
+						4, (u32)(high_base >> 32));
+					high_base += bar_size;
+				} else {
+					if (low_size != bar_size)
+						continue;
+					_hv_pcifront_write_config(hpdev,
+						PCI_BASE_ADDRESS_0 + (4 * i),
+						4,
+						(u32)(low_base & 0xffffff00));
+					low_base += bar_size;
+				}
+			}
+			if (high_size <= 1 && low_size <= 1) {
+				/*
+				 * No need to set the PCI_COMMAND_MEMORY bit as
+				 * the core PCI driver doesn't require the bit
+				 * to be pre-set. Actually here we intentionally
+				 * keep the bit off so that the PCI BAR probing
+				 * in the core PCI driver doesn't cause Hyper-V
+				 * to unnecessarily unmap/map the virtual BARs
+				 * from/to the physical BARs multiple times.
+				 * This reduces the VM boot time significantly
+				 * if the BAR sizes are huge.
+				 */
+				break;
+			}
+		}
+
+		high_size >>= 1;
+		low_size >>= 1;
+	}  while (high_size || low_size);
+
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+}
+
+/*
+ * Assign entries in sysfs pci slot directory.
+ *
+ * Note that this function does not need to lock the children list
+ * because it is called from pci_devices_present_work which
+ * is serialized with hv_eject_device_work because they are on the
+ * same ordered workqueue. Therefore hbus->children list will not change
+ * even when pci_create_slot sleeps.
+ */
+static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
+{
+	struct hv_pci_dev *hpdev;
+	char name[SLOT_NAME_SIZE];
+	int slot_nr;
+
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		if (hpdev->pci_slot)
+			continue;
+
+		slot_nr = PCI_SLOT(wslot_to_devfn(hpdev->desc.win_slot.slot));
+		snprintf(name, SLOT_NAME_SIZE, "%u", hpdev->desc.ser);
+		hpdev->pci_slot = pci_create_slot(hbus->bridge->bus, slot_nr,
+					  name, NULL);
+		if (IS_ERR(hpdev->pci_slot)) {
+			pr_warn("pci_create slot %s failed\n", name);
+			hpdev->pci_slot = NULL;
+		}
+	}
+}
+
+/*
+ * Remove entries in sysfs pci slot directory.
+ */
+static void hv_pci_remove_slots(struct hv_pcibus_device *hbus)
+{
+	struct hv_pci_dev *hpdev;
+
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		if (!hpdev->pci_slot)
+			continue;
+		pci_destroy_slot(hpdev->pci_slot);
+		hpdev->pci_slot = NULL;
+	}
+}
+
+/*
+ * Set NUMA node for the devices on the bus
+ */
+static void hv_pci_assign_numa_node(struct hv_pcibus_device *hbus)
+{
+	struct pci_dev *dev;
+	struct pci_bus *bus = hbus->bridge->bus;
+	struct hv_pci_dev *hv_dev;
+
+	list_for_each_entry(dev, &bus->devices, bus_list) {
+		hv_dev = get_pcichild_wslot(hbus, devfn_to_wslot(dev->devfn));
+		if (!hv_dev)
+			continue;
+
+		if (hv_dev->desc.flags & HV_PCI_DEVICE_FLAG_NUMA_AFFINITY &&
+		    hv_dev->desc.virtual_numa_node < num_possible_nodes())
+			/*
+			 * The kernel may boot with some NUMA nodes offline
+			 * (e.g. in a KDUMP kernel) or with NUMA disabled via
+			 * "numa=off". In those cases, adjust the host provided
+			 * NUMA node to a valid NUMA node used by the kernel.
+			 */
+			set_dev_node(&dev->dev,
+				     numa_map_to_online_node(
+					     hv_dev->desc.virtual_numa_node));
+
+		put_pcichild(hv_dev);
+	}
+}
+
+/**
+ * create_root_hv_pci_bus() - Expose a new root PCI bus
+ * @hbus:	Root PCI bus, as understood by this driver
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int create_root_hv_pci_bus(struct hv_pcibus_device *hbus)
+{
+	int error;
+	struct pci_host_bridge *bridge = hbus->bridge;
+
+	bridge->dev.parent = &hbus->hdev->device;
+	bridge->sysdata = &hbus->sysdata;
+	bridge->ops = &hv_pcifront_ops;
+
+	error = pci_scan_root_bus_bridge(bridge);
+	if (error)
+		return error;
+
+	pci_lock_rescan_remove();
+	hv_pci_assign_numa_node(hbus);
+	pci_bus_assign_resources(bridge->bus);
+	hv_pci_assign_slots(hbus);
+	pci_bus_add_devices(bridge->bus);
+	pci_unlock_rescan_remove();
+	hbus->state = hv_pcibus_installed;
+	return 0;
+}
+
+struct q_res_req_compl {
+	struct completion host_event;
+	struct hv_pci_dev *hpdev;
+};
+
+/**
+ * q_resource_requirements() - Query Resource Requirements
+ * @context:		The completion context.
+ * @resp:		The response that came from the host.
+ * @resp_packet_size:	The size in bytes of resp.
+ *
+ * This function is invoked on completion of a Query Resource
+ * Requirements packet.
+ */
+static void q_resource_requirements(void *context, struct pci_response *resp,
+				    int resp_packet_size)
+{
+	struct q_res_req_compl *completion = context;
+	struct pci_q_res_req_response *q_res_req =
+		(struct pci_q_res_req_response *)resp;
+	s32 status;
+	int i;
+
+	status = (resp_packet_size < sizeof(*q_res_req)) ? -1 : resp->status;
+	if (status < 0) {
+		dev_err(&completion->hpdev->hbus->hdev->device,
+			"query resource requirements failed: %x\n",
+			status);
+	} else {
+		for (i = 0; i < PCI_STD_NUM_BARS; i++) {
+			completion->hpdev->probed_bar[i] =
+				q_res_req->probed_bar[i];
+		}
+	}
+
+	complete(&completion->host_event);
+}
+
+/**
+ * new_pcichild_device() - Create a new child device
+ * @hbus:	The internal struct tracking this root PCI bus.
+ * @desc:	The information supplied so far from the host
+ *              about the device.
+ *
+ * This function creates the tracking structure for a new child
+ * device and kicks off the process of figuring out what it is.
+ *
+ * Return: Pointer to the new tracking struct
+ */
+static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
+		struct hv_pcidev_description *desc)
+{
+	struct hv_pci_dev *hpdev;
+	struct pci_child_message *res_req;
+	struct q_res_req_compl comp_pkt;
+	struct {
+		struct pci_packet init_packet;
+		u8 buffer[sizeof(struct pci_child_message)];
+	} pkt;
+	unsigned long flags;
+	int ret;
+
+	hpdev = kzalloc(sizeof(*hpdev), GFP_KERNEL);
+	if (!hpdev)
+		return NULL;
+
+	hpdev->hbus = hbus;
+
+	memset(&pkt, 0, sizeof(pkt));
+	init_completion(&comp_pkt.host_event);
+	comp_pkt.hpdev = hpdev;
+	pkt.init_packet.compl_ctxt = &comp_pkt;
+	pkt.init_packet.completion_func = q_resource_requirements;
+	res_req = (struct pci_child_message *)&pkt.init_packet.message;
+	res_req->message_type.type = PCI_QUERY_RESOURCE_REQUIREMENTS;
+	res_req->wslot.slot = desc->win_slot.slot;
+
+	ret = vmbus_sendpacket(hbus->hdev->channel, res_req,
+			       sizeof(struct pci_child_message),
+			       (unsigned long)&pkt.init_packet,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret)
+		goto error;
+
+	if (wait_for_response(hbus->hdev, &comp_pkt.host_event))
+		goto error;
+
+	hpdev->desc = *desc;
+	refcount_set(&hpdev->refs, 1);
+	get_pcichild(hpdev);
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+
+	list_add_tail(&hpdev->list_entry, &hbus->children);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+	return hpdev;
+
+error:
+	kfree(hpdev);
+	return NULL;
+}
+
+/**
+ * get_pcichild_wslot() - Find device from slot
+ * @hbus:	Root PCI bus, as understood by this driver
+ * @wslot:	Location on the bus
+ *
+ * This function looks up a PCI device and returns the internal
+ * representation of it.  It acquires a reference on it, so that
+ * the device won't be deleted while somebody is using it.  The
+ * caller is responsible for calling put_pcichild() to release
+ * this reference.
+ *
+ * Return:	Internal representation of a PCI device
+ */
+static struct hv_pci_dev *get_pcichild_wslot(struct hv_pcibus_device *hbus,
+					     u32 wslot)
+{
+	unsigned long flags;
+	struct hv_pci_dev *iter, *hpdev = NULL;
+
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	list_for_each_entry(iter, &hbus->children, list_entry) {
+		if (iter->desc.win_slot.slot == wslot) {
+			hpdev = iter;
+			get_pcichild(hpdev);
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	return hpdev;
+}
+
+/**
+ * pci_devices_present_work() - Handle new list of child devices
+ * @work:	Work struct embedded in struct hv_dr_work
+ *
+ * "Bus Relations" is the Windows term for "children of this
+ * bus."  The terminology is preserved here for people trying to
+ * debug the interaction between Hyper-V and Linux.  This
+ * function is called when the parent partition reports a list
+ * of functions that should be observed under this PCI Express
+ * port (bus).
+ *
+ * This function updates the list, and must tolerate being
+ * called multiple times with the same information.  The typical
+ * number of child devices is one, with very atypical cases
+ * involving three or four, so the algorithms used here can be
+ * simple and inefficient.
+ *
+ * It must also treat the omission of a previously observed device as
+ * notification that the device no longer exists.
+ *
+ * Note that this function is serialized with hv_eject_device_work(),
+ * because both are pushed to the ordered workqueue hbus->wq.
+ */
+static void pci_devices_present_work(struct work_struct *work)
+{
+	u32 child_no;
+	bool found;
+	struct hv_pcidev_description *new_desc;
+	struct hv_pci_dev *hpdev;
+	struct hv_pcibus_device *hbus;
+	struct list_head removed;
+	struct hv_dr_work *dr_wrk;
+	struct hv_dr_state *dr = NULL;
+	unsigned long flags;
+
+	dr_wrk = container_of(work, struct hv_dr_work, wrk);
+	hbus = dr_wrk->bus;
+	kfree(dr_wrk);
+
+	INIT_LIST_HEAD(&removed);
+
+	/* Pull this off the queue and process it if it was the last one. */
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	while (!list_empty(&hbus->dr_list)) {
+		dr = list_first_entry(&hbus->dr_list, struct hv_dr_state,
+				      list_entry);
+		list_del(&dr->list_entry);
+
+		/* Throw this away if the list still has stuff in it. */
+		if (!list_empty(&hbus->dr_list)) {
+			kfree(dr);
+			continue;
+		}
+	}
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	if (!dr)
+		return;
+
+	mutex_lock(&hbus->state_lock);
+
+	/* First, mark all existing children as reported missing. */
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		hpdev->reported_missing = true;
+	}
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	/* Next, add back any reported devices. */
+	for (child_no = 0; child_no < dr->device_count; child_no++) {
+		found = false;
+		new_desc = &dr->func[child_no];
+
+		spin_lock_irqsave(&hbus->device_list_lock, flags);
+		list_for_each_entry(hpdev, &hbus->children, list_entry) {
+			if ((hpdev->desc.win_slot.slot == new_desc->win_slot.slot) &&
+			    (hpdev->desc.v_id == new_desc->v_id) &&
+			    (hpdev->desc.d_id == new_desc->d_id) &&
+			    (hpdev->desc.ser == new_desc->ser)) {
+				hpdev->reported_missing = false;
+				found = true;
+			}
+		}
+		spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+		if (!found) {
+			hpdev = new_pcichild_device(hbus, new_desc);
+			if (!hpdev)
+				dev_err(&hbus->hdev->device,
+					"couldn't record a child device.\n");
+		}
+	}
+
+	/* Move missing children to a list on the stack. */
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	do {
+		found = false;
+		list_for_each_entry(hpdev, &hbus->children, list_entry) {
+			if (hpdev->reported_missing) {
+				found = true;
+				put_pcichild(hpdev);
+				list_move_tail(&hpdev->list_entry, &removed);
+				break;
+			}
+		}
+	} while (found);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	/* Delete everything that should no longer exist. */
+	while (!list_empty(&removed)) {
+		hpdev = list_first_entry(&removed, struct hv_pci_dev,
+					 list_entry);
+		list_del(&hpdev->list_entry);
+
+		if (hpdev->pci_slot)
+			pci_destroy_slot(hpdev->pci_slot);
+
+		put_pcichild(hpdev);
+	}
+
+	switch (hbus->state) {
+	case hv_pcibus_installed:
+		/*
+		 * Tell the core to rescan bus
+		 * because there may have been changes.
+		 */
+		pci_lock_rescan_remove();
+		pci_scan_child_bus(hbus->bridge->bus);
+		hv_pci_assign_numa_node(hbus);
+		hv_pci_assign_slots(hbus);
+		pci_unlock_rescan_remove();
+		break;
+
+	case hv_pcibus_init:
+	case hv_pcibus_probed:
+		survey_child_resources(hbus);
+		break;
+
+	default:
+		break;
+	}
+
+	mutex_unlock(&hbus->state_lock);
+
+	kfree(dr);
+}
+
+/**
+ * hv_pci_start_relations_work() - Queue work to start device discovery
+ * @hbus:	Root PCI bus, as understood by this driver
+ * @dr:		The list of children returned from host
+ *
+ * Return:  0 on success, -errno on failure
+ */
+static int hv_pci_start_relations_work(struct hv_pcibus_device *hbus,
+				       struct hv_dr_state *dr)
+{
+	struct hv_dr_work *dr_wrk;
+	unsigned long flags;
+	bool pending_dr;
+
+	if (hbus->state == hv_pcibus_removing) {
+		dev_info(&hbus->hdev->device,
+			 "PCI VMBus BUS_RELATIONS: ignored\n");
+		return -ENOENT;
+	}
+
+	dr_wrk = kzalloc(sizeof(*dr_wrk), GFP_NOWAIT);
+	if (!dr_wrk)
+		return -ENOMEM;
+
+	INIT_WORK(&dr_wrk->wrk, pci_devices_present_work);
+	dr_wrk->bus = hbus;
+
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	/*
+	 * If pending_dr is true, we have already queued a work,
+	 * which will see the new dr. Otherwise, we need to
+	 * queue a new work.
+	 */
+	pending_dr = !list_empty(&hbus->dr_list);
+	list_add_tail(&dr->list_entry, &hbus->dr_list);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	if (pending_dr)
+		kfree(dr_wrk);
+	else
+		queue_work(hbus->wq, &dr_wrk->wrk);
+
+	return 0;
+}
+
+/**
+ * hv_pci_devices_present() - Handle list of new children
+ * @hbus:      Root PCI bus, as understood by this driver
+ * @relations: Packet from host listing children
+ *
+ * Process a new list of devices on the bus. The list of devices is
+ * discovered by VSP and sent to us via VSP message PCI_BUS_RELATIONS,
+ * whenever a new list of devices for this bus appears.
+ */
+static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
+				   struct pci_bus_relations *relations)
+{
+	struct hv_dr_state *dr;
+	int i;
+
+	dr = kzalloc(struct_size(dr, func, relations->device_count),
+		     GFP_NOWAIT);
+	if (!dr)
+		return;
+
+	dr->device_count = relations->device_count;
+	for (i = 0; i < dr->device_count; i++) {
+		dr->func[i].v_id = relations->func[i].v_id;
+		dr->func[i].d_id = relations->func[i].d_id;
+		dr->func[i].rev = relations->func[i].rev;
+		dr->func[i].prog_intf = relations->func[i].prog_intf;
+		dr->func[i].subclass = relations->func[i].subclass;
+		dr->func[i].base_class = relations->func[i].base_class;
+		dr->func[i].subsystem_id = relations->func[i].subsystem_id;
+		dr->func[i].win_slot = relations->func[i].win_slot;
+		dr->func[i].ser = relations->func[i].ser;
+	}
+
+	if (hv_pci_start_relations_work(hbus, dr))
+		kfree(dr);
+}
+
+/**
+ * hv_pci_devices_present2() - Handle list of new children
+ * @hbus:	Root PCI bus, as understood by this driver
+ * @relations:	Packet from host listing children
+ *
+ * This function is the v2 version of hv_pci_devices_present()
+ */
+static void hv_pci_devices_present2(struct hv_pcibus_device *hbus,
+				    struct pci_bus_relations2 *relations)
+{
+	struct hv_dr_state *dr;
+	int i;
+
+	dr = kzalloc(struct_size(dr, func, relations->device_count),
+		     GFP_NOWAIT);
+	if (!dr)
+		return;
+
+	dr->device_count = relations->device_count;
+	for (i = 0; i < dr->device_count; i++) {
+		dr->func[i].v_id = relations->func[i].v_id;
+		dr->func[i].d_id = relations->func[i].d_id;
+		dr->func[i].rev = relations->func[i].rev;
+		dr->func[i].prog_intf = relations->func[i].prog_intf;
+		dr->func[i].subclass = relations->func[i].subclass;
+		dr->func[i].base_class = relations->func[i].base_class;
+		dr->func[i].subsystem_id = relations->func[i].subsystem_id;
+		dr->func[i].win_slot = relations->func[i].win_slot;
+		dr->func[i].ser = relations->func[i].ser;
+		dr->func[i].flags = relations->func[i].flags;
+		dr->func[i].virtual_numa_node =
+			relations->func[i].virtual_numa_node;
+	}
+
+	if (hv_pci_start_relations_work(hbus, dr))
+		kfree(dr);
+}
+
+/**
+ * hv_eject_device_work() - Asynchronously handles ejection
+ * @work:	Work struct embedded in internal device struct
+ *
+ * This function handles ejecting a device.  Windows will
+ * attempt to gracefully eject a device, waiting 60 seconds to
+ * hear back from the guest OS that this completed successfully.
+ * If this timer expires, the device will be forcibly removed.
+ */
+static void hv_eject_device_work(struct work_struct *work)
+{
+	struct pci_eject_response *ejct_pkt;
+	struct hv_pcibus_device *hbus;
+	struct hv_pci_dev *hpdev;
+	struct pci_dev *pdev;
+	unsigned long flags;
+	int wslot;
+	struct {
+		struct pci_packet pkt;
+		u8 buffer[sizeof(struct pci_eject_response)];
+	} ctxt;
+
+	hpdev = container_of(work, struct hv_pci_dev, wrk);
+	hbus = hpdev->hbus;
+
+	mutex_lock(&hbus->state_lock);
+
+	/*
+	 * Ejection can come before or after the PCI bus has been set up, so
+	 * attempt to find it and tear down the bus state, if it exists.  This
+	 * must be done without constructs like pci_domain_nr(hbus->bridge->bus)
+	 * because hbus->bridge->bus may not exist yet.
+	 */
+	wslot = wslot_to_devfn(hpdev->desc.win_slot.slot);
+	pdev = pci_get_domain_bus_and_slot(hbus->bridge->domain_nr, 0, wslot);
+	if (pdev) {
+		pci_lock_rescan_remove();
+		pci_stop_and_remove_bus_device(pdev);
+		pci_dev_put(pdev);
+		pci_unlock_rescan_remove();
+	}
+
+	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	list_del(&hpdev->list_entry);
+	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+	if (hpdev->pci_slot)
+		pci_destroy_slot(hpdev->pci_slot);
+
+	memset(&ctxt, 0, sizeof(ctxt));
+	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
+	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
+	ejct_pkt->wslot.slot = hpdev->desc.win_slot.slot;
+	vmbus_sendpacket(hbus->hdev->channel, ejct_pkt,
+			 sizeof(*ejct_pkt), 0,
+			 VM_PKT_DATA_INBAND, 0);
+
+	/* For the get_pcichild() in hv_pci_eject_device() */
+	put_pcichild(hpdev);
+	/* For the two refs got in new_pcichild_device() */
+	put_pcichild(hpdev);
+	put_pcichild(hpdev);
+	/* hpdev has been freed. Do not use it any more. */
+
+	mutex_unlock(&hbus->state_lock);
+}
+
+/**
+ * hv_pci_eject_device() - Handles device ejection
+ * @hpdev:	Internal device tracking struct
+ *
+ * This function is invoked when an ejection packet arrives.  It
+ * just schedules work so that we don't re-enter the packet
+ * delivery code handling the ejection.
+ */
+static void hv_pci_eject_device(struct hv_pci_dev *hpdev)
+{
+	struct hv_pcibus_device *hbus = hpdev->hbus;
+	struct hv_device *hdev = hbus->hdev;
+
+	if (hbus->state == hv_pcibus_removing) {
+		dev_info(&hdev->device, "PCI VMBus EJECT: ignored\n");
+		return;
+	}
+
+	get_pcichild(hpdev);
+	INIT_WORK(&hpdev->wrk, hv_eject_device_work);
+	queue_work(hbus->wq, &hpdev->wrk);
+}
+
+/**
+ * hv_pci_onchannelcallback() - Handles incoming packets
+ * @context:	Internal bus tracking struct
+ *
+ * This function is invoked whenever the host sends a packet to
+ * this channel (which is private to this root PCI bus).
+ */
+static void hv_pci_onchannelcallback(void *context)
+{
+	const int packet_size = 0x100;
+	int ret;
+	struct hv_pcibus_device *hbus = context;
+	struct vmbus_channel *chan = hbus->hdev->channel;
+	u32 bytes_recvd;
+	u64 req_id, req_addr;
+	struct vmpacket_descriptor *desc;
+	unsigned char *buffer;
+	int bufferlen = packet_size;
+	struct pci_packet *comp_packet;
+	struct pci_response *response;
+	struct pci_incoming_message *new_message;
+	struct pci_bus_relations *bus_rel;
+	struct pci_bus_relations2 *bus_rel2;
+	struct pci_dev_inval_block *inval;
+	struct pci_dev_incoming *dev_message;
+	struct hv_pci_dev *hpdev;
+	unsigned long flags;
+
+	buffer = kmalloc(bufferlen, GFP_ATOMIC);
+	if (!buffer)
+		return;
+
+	while (1) {
+		ret = vmbus_recvpacket_raw(chan, buffer, bufferlen,
+					   &bytes_recvd, &req_id);
+
+		if (ret == -ENOBUFS) {
+			kfree(buffer);
+			/* Handle large packet */
+			bufferlen = bytes_recvd;
+			buffer = kmalloc(bytes_recvd, GFP_ATOMIC);
+			if (!buffer)
+				return;
+			continue;
+		}
+
+		/* Zero length indicates there are no more packets. */
+		if (ret || !bytes_recvd)
+			break;
+
+		/*
+		 * All incoming packets must be at least as large as a
+		 * response.
+		 */
+		if (bytes_recvd <= sizeof(struct pci_response))
+			continue;
+		desc = (struct vmpacket_descriptor *)buffer;
+
+		switch (desc->type) {
+		case VM_PKT_COMP:
+
+			lock_requestor(chan, flags);
+			req_addr = __vmbus_request_addr_match(chan, req_id,
+							      VMBUS_RQST_ADDR_ANY);
+			if (req_addr == VMBUS_RQST_ERROR) {
+				unlock_requestor(chan, flags);
+				dev_err(&hbus->hdev->device,
+					"Invalid transaction ID %llx\n",
+					req_id);
+				break;
+			}
+			comp_packet = (struct pci_packet *)req_addr;
+			response = (struct pci_response *)buffer;
+			/*
+			 * Call ->completion_func() within the critical section to make
+			 * sure that the packet pointer is still valid during the call:
+			 * here 'valid' means that there's a task still waiting for the
+			 * completion, and that the packet data is still on the waiting
+			 * task's stack.  Cf. hv_compose_msi_msg().
+			 */
+			comp_packet->completion_func(comp_packet->compl_ctxt,
+						     response,
+						     bytes_recvd);
+			unlock_requestor(chan, flags);
+			break;
+
+		case VM_PKT_DATA_INBAND:
+
+			new_message = (struct pci_incoming_message *)buffer;
+			switch (new_message->message_type.type) {
+			case PCI_BUS_RELATIONS:
+
+				bus_rel = (struct pci_bus_relations *)buffer;
+				if (bytes_recvd < sizeof(*bus_rel) ||
+				    bytes_recvd <
+					struct_size(bus_rel, func,
+						    bus_rel->device_count)) {
+					dev_err(&hbus->hdev->device,
+						"bus relations too small\n");
+					break;
+				}
+
+				hv_pci_devices_present(hbus, bus_rel);
+				break;
+
+			case PCI_BUS_RELATIONS2:
+
+				bus_rel2 = (struct pci_bus_relations2 *)buffer;
+				if (bytes_recvd < sizeof(*bus_rel2) ||
+				    bytes_recvd <
+					struct_size(bus_rel2, func,
+						    bus_rel2->device_count)) {
+					dev_err(&hbus->hdev->device,
+						"bus relations v2 too small\n");
+					break;
+				}
+
+				hv_pci_devices_present2(hbus, bus_rel2);
+				break;
+
+			case PCI_EJECT:
+
+				dev_message = (struct pci_dev_incoming *)buffer;
+				if (bytes_recvd < sizeof(*dev_message)) {
+					dev_err(&hbus->hdev->device,
+						"eject message too small\n");
+					break;
+				}
+				hpdev = get_pcichild_wslot(hbus,
+						      dev_message->wslot.slot);
+				if (hpdev) {
+					hv_pci_eject_device(hpdev);
+					put_pcichild(hpdev);
+				}
+				break;
+
+			case PCI_INVALIDATE_BLOCK:
+
+				inval = (struct pci_dev_inval_block *)buffer;
+				if (bytes_recvd < sizeof(*inval)) {
+					dev_err(&hbus->hdev->device,
+						"invalidate message too small\n");
+					break;
+				}
+				hpdev = get_pcichild_wslot(hbus,
+							   inval->wslot.slot);
+				if (hpdev) {
+					if (hpdev->block_invalidate) {
+						hpdev->block_invalidate(
+						    hpdev->invalidate_context,
+						    inval->block_mask);
+					}
+					put_pcichild(hpdev);
+				}
+				break;
+
+			default:
+				dev_warn(&hbus->hdev->device,
+					"Unimplemented protocol message %x\n",
+					new_message->message_type.type);
+				break;
+			}
+			break;
+
+		default:
+			dev_err(&hbus->hdev->device,
+				"unhandled packet type %d, tid %llx len %d\n",
+				desc->type, req_id, bytes_recvd);
+			break;
+		}
+	}
+
+	kfree(buffer);
+}
+
+/**
+ * hv_pci_protocol_negotiation() - Set up protocol
+ * @hdev:		VMBus's tracking struct for this root PCI bus.
+ * @version:		Array of supported channel protocol versions in
+ *			the order of probing - highest go first.
+ * @num_version:	Number of elements in the version array.
+ *
+ * This driver is intended to support running on Windows 10
+ * (server) and later versions. It will not run on earlier
+ * versions, as they assume that many of the operations which
+ * Linux needs accomplished with a spinlock held were done via
+ * asynchronous messaging via VMBus.  Windows 10 increases the
+ * surface area of PCI emulation so that these actions can take
+ * place by suspending a virtual processor for their duration.
+ *
+ * This function negotiates the channel protocol version,
+ * failing if the host doesn't support the necessary protocol
+ * level.
+ */
+static int hv_pci_protocol_negotiation(struct hv_device *hdev,
+				       enum pci_protocol_version_t version[],
+				       int num_version)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct pci_version_request *version_req;
+	struct hv_pci_compl comp_pkt;
+	struct pci_packet *pkt;
+	int ret;
+	int i;
+
+	/*
+	 * Initiate the handshake with the host and negotiate
+	 * a version that the host can support. We start with the
+	 * highest version number and go down if the host cannot
+	 * support it.
+	 */
+	pkt = kzalloc(sizeof(*pkt) + sizeof(*version_req), GFP_KERNEL);
+	if (!pkt)
+		return -ENOMEM;
+
+	init_completion(&comp_pkt.host_event);
+	pkt->completion_func = hv_pci_generic_compl;
+	pkt->compl_ctxt = &comp_pkt;
+	version_req = (struct pci_version_request *)&pkt->message;
+	version_req->message_type.type = PCI_QUERY_PROTOCOL_VERSION;
+
+	for (i = 0; i < num_version; i++) {
+		version_req->protocol_version = version[i];
+		ret = vmbus_sendpacket(hdev->channel, version_req,
+				sizeof(struct pci_version_request),
+				(unsigned long)pkt, VM_PKT_DATA_INBAND,
+				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+		if (!ret)
+			ret = wait_for_response(hdev, &comp_pkt.host_event);
+
+		if (ret) {
+			dev_err(&hdev->device,
+				"PCI Pass-through VSP failed to request version: %d",
+				ret);
+			goto exit;
+		}
+
+		if (comp_pkt.completion_status >= 0) {
+			hbus->protocol_version = version[i];
+			dev_info(&hdev->device,
+				"PCI VMBus probing: Using version %#x\n",
+				hbus->protocol_version);
+			goto exit;
+		}
+
+		if (comp_pkt.completion_status != STATUS_REVISION_MISMATCH) {
+			dev_err(&hdev->device,
+				"PCI Pass-through VSP failed version request: %#x",
+				comp_pkt.completion_status);
+			ret = -EPROTO;
+			goto exit;
+		}
+
+		reinit_completion(&comp_pkt.host_event);
+	}
+
+	dev_err(&hdev->device,
+		"PCI pass-through VSP failed to find supported version");
+	ret = -EPROTO;
+
+exit:
+	kfree(pkt);
+	return ret;
+}
+
+/**
+ * hv_pci_free_bridge_windows() - Release memory regions for the
+ * bus
+ * @hbus:	Root PCI bus, as understood by this driver
+ */
+static void hv_pci_free_bridge_windows(struct hv_pcibus_device *hbus)
+{
+	/*
+	 * Set the resources back to the way they looked when they
+	 * were allocated by setting IORESOURCE_BUSY again.
+	 */
+
+	if (hbus->low_mmio_space && hbus->low_mmio_res) {
+		hbus->low_mmio_res->flags |= IORESOURCE_BUSY;
+		vmbus_free_mmio(hbus->low_mmio_res->start,
+				resource_size(hbus->low_mmio_res));
+	}
+
+	if (hbus->high_mmio_space && hbus->high_mmio_res) {
+		hbus->high_mmio_res->flags |= IORESOURCE_BUSY;
+		vmbus_free_mmio(hbus->high_mmio_res->start,
+				resource_size(hbus->high_mmio_res));
+	}
+}
+
+/**
+ * hv_pci_allocate_bridge_windows() - Allocate memory regions
+ * for the bus
+ * @hbus:	Root PCI bus, as understood by this driver
+ *
+ * This function calls vmbus_allocate_mmio(), which is itself a
+ * bit of a compromise.  Ideally, we might change the pnp layer
+ * in the kernel such that it comprehends either PCI devices
+ * which are "grandchildren of ACPI," with some intermediate bus
+ * node (in this case, VMBus) or change it such that it
+ * understands VMBus.  The pnp layer, however, has been declared
+ * deprecated, and not subject to change.
+ *
+ * The workaround, implemented here, is to ask VMBus to allocate
+ * MMIO space for this bus.  VMBus itself knows which ranges are
+ * appropriate by looking at its own ACPI objects.  Then, after
+ * these ranges are claimed, they're modified to look like they
+ * would have looked if the ACPI and pnp code had allocated
+ * bridge windows.  These descriptors have to exist in this form
+ * in order to satisfy the code which will get invoked when the
+ * endpoint PCI function driver calls request_mem_region() or
+ * request_mem_region_exclusive().
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_pci_allocate_bridge_windows(struct hv_pcibus_device *hbus)
+{
+	resource_size_t align;
+	int ret;
+
+	if (hbus->low_mmio_space) {
+		align = 1ULL << (63 - __builtin_clzll(hbus->low_mmio_space));
+		ret = vmbus_allocate_mmio(&hbus->low_mmio_res, hbus->hdev, 0,
+					  (u64)(u32)0xffffffff,
+					  hbus->low_mmio_space,
+					  align, false);
+		if (ret) {
+			dev_err(&hbus->hdev->device,
+				"Need %#llx of low MMIO space. Consider reconfiguring the VM.\n",
+				hbus->low_mmio_space);
+			return ret;
+		}
+
+		/* Modify this resource to become a bridge window. */
+		hbus->low_mmio_res->flags |= IORESOURCE_WINDOW;
+		hbus->low_mmio_res->flags &= ~IORESOURCE_BUSY;
+		pci_add_resource(&hbus->bridge->windows, hbus->low_mmio_res);
+	}
+
+	if (hbus->high_mmio_space) {
+		align = 1ULL << (63 - __builtin_clzll(hbus->high_mmio_space));
+		ret = vmbus_allocate_mmio(&hbus->high_mmio_res, hbus->hdev,
+					  0x100000000, -1,
+					  hbus->high_mmio_space, align,
+					  false);
+		if (ret) {
+			dev_err(&hbus->hdev->device,
+				"Need %#llx of high MMIO space. Consider reconfiguring the VM.\n",
+				hbus->high_mmio_space);
+			goto release_low_mmio;
+		}
+
+		/* Modify this resource to become a bridge window. */
+		hbus->high_mmio_res->flags |= IORESOURCE_WINDOW;
+		hbus->high_mmio_res->flags &= ~IORESOURCE_BUSY;
+		pci_add_resource(&hbus->bridge->windows, hbus->high_mmio_res);
+	}
+
+	return 0;
+
+release_low_mmio:
+	if (hbus->low_mmio_res) {
+		vmbus_free_mmio(hbus->low_mmio_res->start,
+				resource_size(hbus->low_mmio_res));
+	}
+
+	return ret;
+}
+
+/**
+ * hv_allocate_config_window() - Find MMIO space for PCI Config
+ * @hbus:	Root PCI bus, as understood by this driver
+ *
+ * This function claims memory-mapped I/O space for accessing
+ * configuration space for the functions on this bus.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_allocate_config_window(struct hv_pcibus_device *hbus)
+{
+	int ret;
+
+	/*
+	 * Set up a region of MMIO space to use for accessing configuration
+	 * space.
+	 */
+	ret = vmbus_allocate_mmio(&hbus->mem_config, hbus->hdev, 0, -1,
+				  PCI_CONFIG_MMIO_LENGTH, 0x1000, false);
+	if (ret)
+		return ret;
+
+	/*
+	 * vmbus_allocate_mmio() gets used for allocating both device endpoint
+	 * resource claims (those which cannot be overlapped) and the ranges
+	 * which are valid for the children of this bus, which are intended
+	 * to be overlapped by those children.  Set the flag on this claim
+	 * meaning that this region can't be overlapped.
+	 */
+
+	hbus->mem_config->flags |= IORESOURCE_BUSY;
+
+	return 0;
+}
+
+static void hv_free_config_window(struct hv_pcibus_device *hbus)
+{
+	vmbus_free_mmio(hbus->mem_config->start, PCI_CONFIG_MMIO_LENGTH);
+}
+
+static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs);
+
+/**
+ * hv_pci_enter_d0() - Bring the "bus" into the D0 power state
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_pci_enter_d0(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct pci_bus_d0_entry *d0_entry;
+	struct hv_pci_compl comp_pkt;
+	struct pci_packet *pkt;
+	bool retry = true;
+	int ret;
+
+enter_d0_retry:
+	/*
+	 * Tell the host that the bus is ready to use, and moved into the
+	 * powered-on state.  This includes telling the host which region
+	 * of memory-mapped I/O space has been chosen for configuration space
+	 * access.
+	 */
+	pkt = kzalloc(sizeof(*pkt) + sizeof(*d0_entry), GFP_KERNEL);
+	if (!pkt)
+		return -ENOMEM;
+
+	init_completion(&comp_pkt.host_event);
+	pkt->completion_func = hv_pci_generic_compl;
+	pkt->compl_ctxt = &comp_pkt;
+	d0_entry = (struct pci_bus_d0_entry *)&pkt->message;
+	d0_entry->message_type.type = PCI_BUS_D0ENTRY;
+	d0_entry->mmio_base = hbus->mem_config->start;
+
+	ret = vmbus_sendpacket(hdev->channel, d0_entry, sizeof(*d0_entry),
+			       (unsigned long)pkt, VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (!ret)
+		ret = wait_for_response(hdev, &comp_pkt.host_event);
+
+	if (ret)
+		goto exit;
+
+	/*
+	 * In certain case (Kdump) the pci device of interest was
+	 * not cleanly shut down and resource is still held on host
+	 * side, the host could return invalid device status.
+	 * We need to explicitly request host to release the resource
+	 * and try to enter D0 again.
+	 */
+	if (comp_pkt.completion_status < 0 && retry) {
+		retry = false;
+
+		dev_err(&hdev->device, "Retrying D0 Entry\n");
+
+		/*
+		 * Hv_pci_bus_exit() calls hv_send_resource_released()
+		 * to free up resources of its child devices.
+		 * In the kdump kernel we need to set the
+		 * wslot_res_allocated to 255 so it scans all child
+		 * devices to release resources allocated in the
+		 * normal kernel before panic happened.
+		 */
+		hbus->wslot_res_allocated = 255;
+
+		ret = hv_pci_bus_exit(hdev, true);
+
+		if (ret == 0) {
+			kfree(pkt);
+			goto enter_d0_retry;
+		}
+		dev_err(&hdev->device,
+			"Retrying D0 failed with ret %d\n", ret);
+	}
+
+	if (comp_pkt.completion_status < 0) {
+		dev_err(&hdev->device,
+			"PCI Pass-through VSP failed D0 Entry with status %x\n",
+			comp_pkt.completion_status);
+		ret = -EPROTO;
+		goto exit;
+	}
+
+	ret = 0;
+
+exit:
+	kfree(pkt);
+	return ret;
+}
+
+/**
+ * hv_pci_query_relations() - Ask host to send list of child
+ * devices
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_pci_query_relations(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct pci_message message;
+	struct completion comp;
+	int ret;
+
+	/* Ask the host to send along the list of child devices */
+	init_completion(&comp);
+	if (cmpxchg(&hbus->survey_event, NULL, &comp))
+		return -ENOTEMPTY;
+
+	memset(&message, 0, sizeof(message));
+	message.type = PCI_QUERY_BUS_RELATIONS;
+
+	ret = vmbus_sendpacket(hdev->channel, &message, sizeof(message),
+			       0, VM_PKT_DATA_INBAND, 0);
+	if (!ret)
+		ret = wait_for_response(hdev, &comp);
+
+	/*
+	 * In the case of fast device addition/removal, it's possible that
+	 * vmbus_sendpacket() or wait_for_response() returns -ENODEV but we
+	 * already got a PCI_BUS_RELATIONS* message from the host and the
+	 * channel callback already scheduled a work to hbus->wq, which can be
+	 * running pci_devices_present_work() -> survey_child_resources() ->
+	 * complete(&hbus->survey_event), even after hv_pci_query_relations()
+	 * exits and the stack variable 'comp' is no longer valid; as a result,
+	 * a hang or a page fault may happen when the complete() calls
+	 * raw_spin_lock_irqsave(). Flush hbus->wq before we exit from
+	 * hv_pci_query_relations() to avoid the issues. Note: if 'ret' is
+	 * -ENODEV, there can't be any more work item scheduled to hbus->wq
+	 * after the flush_workqueue(): see vmbus_onoffer_rescind() ->
+	 * vmbus_reset_channel_cb(), vmbus_rescind_cleanup() ->
+	 * channel->rescind = true.
+	 */
+	flush_workqueue(hbus->wq);
+
+	return ret;
+}
+
+/**
+ * hv_send_resources_allocated() - Report local resource choices
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ *
+ * The host OS is expecting to be sent a request as a message
+ * which contains all the resources that the device will use.
+ * The response contains those same resources, "translated"
+ * which is to say, the values which should be used by the
+ * hardware, when it delivers an interrupt.  (MMIO resources are
+ * used in local terms.)  This is nice for Windows, and lines up
+ * with the FDO/PDO split, which doesn't exist in Linux.  Linux
+ * is deeply expecting to scan an emulated PCI configuration
+ * space.  So this message is sent here only to drive the state
+ * machine on the host forward.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_send_resources_allocated(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct pci_resources_assigned *res_assigned;
+	struct pci_resources_assigned2 *res_assigned2;
+	struct hv_pci_compl comp_pkt;
+	struct hv_pci_dev *hpdev;
+	struct pci_packet *pkt;
+	size_t size_res;
+	int wslot;
+	int ret;
+
+	size_res = (hbus->protocol_version < PCI_PROTOCOL_VERSION_1_2)
+			? sizeof(*res_assigned) : sizeof(*res_assigned2);
+
+	pkt = kmalloc(sizeof(*pkt) + size_res, GFP_KERNEL);
+	if (!pkt)
+		return -ENOMEM;
+
+	ret = 0;
+
+	for (wslot = 0; wslot < 256; wslot++) {
+		hpdev = get_pcichild_wslot(hbus, wslot);
+		if (!hpdev)
+			continue;
+
+		memset(pkt, 0, sizeof(*pkt) + size_res);
+		init_completion(&comp_pkt.host_event);
+		pkt->completion_func = hv_pci_generic_compl;
+		pkt->compl_ctxt = &comp_pkt;
+
+		if (hbus->protocol_version < PCI_PROTOCOL_VERSION_1_2) {
+			res_assigned =
+				(struct pci_resources_assigned *)&pkt->message;
+			res_assigned->message_type.type =
+				PCI_RESOURCES_ASSIGNED;
+			res_assigned->wslot.slot = hpdev->desc.win_slot.slot;
+		} else {
+			res_assigned2 =
+				(struct pci_resources_assigned2 *)&pkt->message;
+			res_assigned2->message_type.type =
+				PCI_RESOURCES_ASSIGNED2;
+			res_assigned2->wslot.slot = hpdev->desc.win_slot.slot;
+		}
+		put_pcichild(hpdev);
+
+		ret = vmbus_sendpacket(hdev->channel, &pkt->message,
+				size_res, (unsigned long)pkt,
+				VM_PKT_DATA_INBAND,
+				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+		if (!ret)
+			ret = wait_for_response(hdev, &comp_pkt.host_event);
+		if (ret)
+			break;
+
+		if (comp_pkt.completion_status < 0) {
+			ret = -EPROTO;
+			dev_err(&hdev->device,
+				"resource allocated returned 0x%x",
+				comp_pkt.completion_status);
+			break;
+		}
+
+		hbus->wslot_res_allocated = wslot;
+	}
+
+	kfree(pkt);
+	return ret;
+}
+
+/**
+ * hv_send_resources_released() - Report local resources
+ * released
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_send_resources_released(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct pci_child_message pkt;
+	struct hv_pci_dev *hpdev;
+	int wslot;
+	int ret;
+
+	for (wslot = hbus->wslot_res_allocated; wslot >= 0; wslot--) {
+		hpdev = get_pcichild_wslot(hbus, wslot);
+		if (!hpdev)
+			continue;
+
+		memset(&pkt, 0, sizeof(pkt));
+		pkt.message_type.type = PCI_RESOURCES_RELEASED;
+		pkt.wslot.slot = hpdev->desc.win_slot.slot;
+
+		put_pcichild(hpdev);
+
+		ret = vmbus_sendpacket(hdev->channel, &pkt, sizeof(pkt), 0,
+				       VM_PKT_DATA_INBAND, 0);
+		if (ret)
+			return ret;
+
+		hbus->wslot_res_allocated = wslot - 1;
+	}
+
+	hbus->wslot_res_allocated = -1;
+
+	return 0;
+}
+
+#define HVPCI_DOM_MAP_SIZE (64 * 1024)
+static DECLARE_BITMAP(hvpci_dom_map, HVPCI_DOM_MAP_SIZE);
+
+/*
+ * PCI domain number 0 is used by emulated devices on Gen1 VMs, so define 0
+ * as invalid for passthrough PCI devices of this driver.
+ */
+#define HVPCI_DOM_INVALID 0
+
+/**
+ * hv_get_dom_num() - Get a valid PCI domain number
+ * Check if the PCI domain number is in use, and return another number if
+ * it is in use.
+ *
+ * @dom: Requested domain number
+ *
+ * return: domain number on success, HVPCI_DOM_INVALID on failure
+ */
+static u16 hv_get_dom_num(u16 dom)
+{
+	unsigned int i;
+
+	if (test_and_set_bit(dom, hvpci_dom_map) == 0)
+		return dom;
+
+	for_each_clear_bit(i, hvpci_dom_map, HVPCI_DOM_MAP_SIZE) {
+		if (test_and_set_bit(i, hvpci_dom_map) == 0)
+			return i;
+	}
+
+	return HVPCI_DOM_INVALID;
+}
+
+/**
+ * hv_put_dom_num() - Mark the PCI domain number as free
+ * @dom: Domain number to be freed
+ */
+static void hv_put_dom_num(u16 dom)
+{
+	clear_bit(dom, hvpci_dom_map);
+}
+
+/**
+ * hv_pci_probe() - New VMBus channel probe, for a root PCI bus
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ * @dev_id:	Identifies the device itself
+ *
+ * Return: 0 on success, -errno on failure
+ */
+static int hv_pci_probe(struct hv_device *hdev,
+			const struct hv_vmbus_device_id *dev_id)
+{
+	struct pci_host_bridge *bridge;
+	struct hv_pcibus_device *hbus;
+	u16 dom_req, dom;
+	char *name;
+	int ret;
+
+	bridge = devm_pci_alloc_host_bridge(&hdev->device, 0);
+	if (!bridge)
+		return -ENOMEM;
+
+	hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
+	if (!hbus)
+		return -ENOMEM;
+
+	hbus->bridge = bridge;
+	mutex_init(&hbus->state_lock);
+	hbus->state = hv_pcibus_init;
+	hbus->wslot_res_allocated = -1;
+
+	/*
+	 * The PCI bus "domain" is what is called "segment" in ACPI and other
+	 * specs. Pull it from the instance ID, to get something usually
+	 * unique. In rare cases of collision, we will find out another number
+	 * not in use.
+	 *
+	 * Note that, since this code only runs in a Hyper-V VM, Hyper-V
+	 * together with this guest driver can guarantee that (1) The only
+	 * domain used by Gen1 VMs for something that looks like a physical
+	 * PCI bus (which is actually emulated by the hypervisor) is domain 0.
+	 * (2) There will be no overlap between domains (after fixing possible
+	 * collisions) in the same VM.
+	 */
+	dom_req = hdev->dev_instance.b[5] << 8 | hdev->dev_instance.b[4];
+	dom = hv_get_dom_num(dom_req);
+
+	if (dom == HVPCI_DOM_INVALID) {
+		dev_err(&hdev->device,
+			"Unable to use dom# 0x%x or other numbers", dom_req);
+		ret = -EINVAL;
+		goto free_bus;
+	}
+
+	if (dom != dom_req)
+		dev_info(&hdev->device,
+			 "PCI dom# 0x%x has collision, using 0x%x",
+			 dom_req, dom);
+
+	hbus->bridge->domain_nr = dom;
+#ifdef CONFIG_X86
+	hbus->sysdata.domain = dom;
+	hbus->use_calls = !!(ms_hyperv.hints & HV_X64_USE_MMIO_HYPERCALLS);
+#elif defined(CONFIG_ARM64)
+	/*
+	 * Set the PCI bus parent to be the corresponding VMbus
+	 * device. Then the VMbus device will be assigned as the
+	 * ACPI companion in pcibios_root_bridge_prepare() and
+	 * pci_dma_configure() will propagate device coherence
+	 * information to devices created on the bus.
+	 */
+	hbus->sysdata.parent = hdev->device.parent;
+	hbus->use_calls = false;
+#endif
+
+	hbus->hdev = hdev;
+	INIT_LIST_HEAD(&hbus->children);
+	INIT_LIST_HEAD(&hbus->dr_list);
+	spin_lock_init(&hbus->config_lock);
+	spin_lock_init(&hbus->device_list_lock);
+	hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,
+					   hbus->bridge->domain_nr);
+	if (!hbus->wq) {
+		ret = -ENOMEM;
+		goto free_dom;
+	}
+
+	hdev->channel->next_request_id_callback = vmbus_next_request_id;
+	hdev->channel->request_addr_callback = vmbus_request_addr;
+	hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE;
+
+	ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
+			 hv_pci_onchannelcallback, hbus);
+	if (ret)
+		goto destroy_wq;
+
+	hv_set_drvdata(hdev, hbus);
+
+	ret = hv_pci_protocol_negotiation(hdev, pci_protocol_versions,
+					  ARRAY_SIZE(pci_protocol_versions));
+	if (ret)
+		goto close;
+
+	ret = hv_allocate_config_window(hbus);
+	if (ret)
+		goto close;
+
+	hbus->cfg_addr = ioremap(hbus->mem_config->start,
+				 PCI_CONFIG_MMIO_LENGTH);
+	if (!hbus->cfg_addr) {
+		dev_err(&hdev->device,
+			"Unable to map a virtual address for config space\n");
+		ret = -ENOMEM;
+		goto free_config;
+	}
+
+	name = kasprintf(GFP_KERNEL, "%pUL", &hdev->dev_instance);
+	if (!name) {
+		ret = -ENOMEM;
+		goto unmap;
+	}
+
+	hbus->fwnode = irq_domain_alloc_named_fwnode(name);
+	kfree(name);
+	if (!hbus->fwnode) {
+		ret = -ENOMEM;
+		goto unmap;
+	}
+
+	ret = hv_pcie_init_irq_domain(hbus);
+	if (ret)
+		goto free_fwnode;
+
+	ret = hv_pci_query_relations(hdev);
+	if (ret)
+		goto free_irq_domain;
+
+	mutex_lock(&hbus->state_lock);
+
+	ret = hv_pci_enter_d0(hdev);
+	if (ret)
+		goto release_state_lock;
+
+	ret = hv_pci_allocate_bridge_windows(hbus);
+	if (ret)
+		goto exit_d0;
+
+	ret = hv_send_resources_allocated(hdev);
+	if (ret)
+		goto free_windows;
+
+	prepopulate_bars(hbus);
+
+	hbus->state = hv_pcibus_probed;
+
+	ret = create_root_hv_pci_bus(hbus);
+	if (ret)
+		goto free_windows;
+
+	mutex_unlock(&hbus->state_lock);
+	return 0;
+
+free_windows:
+	hv_pci_free_bridge_windows(hbus);
+exit_d0:
+	(void) hv_pci_bus_exit(hdev, true);
+release_state_lock:
+	mutex_unlock(&hbus->state_lock);
+free_irq_domain:
+	irq_domain_remove(hbus->irq_domain);
+free_fwnode:
+	irq_domain_free_fwnode(hbus->fwnode);
+unmap:
+	iounmap(hbus->cfg_addr);
+free_config:
+	hv_free_config_window(hbus);
+close:
+	vmbus_close(hdev->channel);
+destroy_wq:
+	destroy_workqueue(hbus->wq);
+free_dom:
+	hv_put_dom_num(hbus->bridge->domain_nr);
+free_bus:
+	kfree(hbus);
+	return ret;
+}
+
+static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	struct vmbus_channel *chan = hdev->channel;
+	struct {
+		struct pci_packet teardown_packet;
+		u8 buffer[sizeof(struct pci_message)];
+	} pkt;
+	struct hv_pci_compl comp_pkt;
+	struct hv_pci_dev *hpdev, *tmp;
+	unsigned long flags;
+	u64 trans_id;
+	int ret;
+
+	/*
+	 * After the host sends the RESCIND_CHANNEL message, it doesn't
+	 * access the per-channel ringbuffer any longer.
+	 */
+	if (chan->rescind)
+		return 0;
+
+	if (!keep_devs) {
+		struct list_head removed;
+
+		/* Move all present children to the list on stack */
+		INIT_LIST_HEAD(&removed);
+		spin_lock_irqsave(&hbus->device_list_lock, flags);
+		list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry)
+			list_move_tail(&hpdev->list_entry, &removed);
+		spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+		/* Remove all children in the list */
+		list_for_each_entry_safe(hpdev, tmp, &removed, list_entry) {
+			list_del(&hpdev->list_entry);
+			if (hpdev->pci_slot)
+				pci_destroy_slot(hpdev->pci_slot);
+			/* For the two refs got in new_pcichild_device() */
+			put_pcichild(hpdev);
+			put_pcichild(hpdev);
+		}
+	}
+
+	ret = hv_send_resources_released(hdev);
+	if (ret) {
+		dev_err(&hdev->device,
+			"Couldn't send resources released packet(s)\n");
+		return ret;
+	}
+
+	memset(&pkt.teardown_packet, 0, sizeof(pkt.teardown_packet));
+	init_completion(&comp_pkt.host_event);
+	pkt.teardown_packet.completion_func = hv_pci_generic_compl;
+	pkt.teardown_packet.compl_ctxt = &comp_pkt;
+	pkt.teardown_packet.message[0].type = PCI_BUS_D0EXIT;
+
+	ret = vmbus_sendpacket_getid(chan, &pkt.teardown_packet.message,
+				     sizeof(struct pci_message),
+				     (unsigned long)&pkt.teardown_packet,
+				     &trans_id, VM_PKT_DATA_INBAND,
+				     VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+	if (ret)
+		return ret;
+
+	if (wait_for_completion_timeout(&comp_pkt.host_event, 10 * HZ) == 0) {
+		/*
+		 * The completion packet on the stack becomes invalid after
+		 * 'return'; remove the ID from the VMbus requestor if the
+		 * identifier is still mapped to/associated with the packet.
+		 *
+		 * Cf. hv_pci_onchannelcallback().
+		 */
+		vmbus_request_addr_match(chan, trans_id,
+					 (unsigned long)&pkt.teardown_packet);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/**
+ * hv_pci_remove() - Remove routine for this VMBus channel
+ * @hdev:	VMBus's tracking struct for this root PCI bus
+ */
+static void hv_pci_remove(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus;
+
+	hbus = hv_get_drvdata(hdev);
+	if (hbus->state == hv_pcibus_installed) {
+		tasklet_disable(&hdev->channel->callback_event);
+		hbus->state = hv_pcibus_removing;
+		tasklet_enable(&hdev->channel->callback_event);
+		destroy_workqueue(hbus->wq);
+		hbus->wq = NULL;
+		/*
+		 * At this point, no work is running or can be scheduled
+		 * on hbus-wq. We can't race with hv_pci_devices_present()
+		 * or hv_pci_eject_device(), it's safe to proceed.
+		 */
+
+		/* Remove the bus from PCI's point of view. */
+		pci_lock_rescan_remove();
+		pci_stop_root_bus(hbus->bridge->bus);
+		hv_pci_remove_slots(hbus);
+		pci_remove_root_bus(hbus->bridge->bus);
+		pci_unlock_rescan_remove();
+	}
+
+	hv_pci_bus_exit(hdev, false);
+
+	vmbus_close(hdev->channel);
+
+	iounmap(hbus->cfg_addr);
+	hv_free_config_window(hbus);
+	hv_pci_free_bridge_windows(hbus);
+	irq_domain_remove(hbus->irq_domain);
+	irq_domain_free_fwnode(hbus->fwnode);
+
+	hv_put_dom_num(hbus->bridge->domain_nr);
+
+	kfree(hbus);
+}
+
+static int hv_pci_suspend(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	enum hv_pcibus_state old_state;
+	int ret;
+
+	/*
+	 * hv_pci_suspend() must make sure there are no pending work items
+	 * before calling vmbus_close(), since it runs in a process context
+	 * as a callback in dpm_suspend().  When it starts to run, the channel
+	 * callback hv_pci_onchannelcallback(), which runs in a tasklet
+	 * context, can be still running concurrently and scheduling new work
+	 * items onto hbus->wq in hv_pci_devices_present() and
+	 * hv_pci_eject_device(), and the work item handlers can access the
+	 * vmbus channel, which can be being closed by hv_pci_suspend(), e.g.
+	 * the work item handler pci_devices_present_work() ->
+	 * new_pcichild_device() writes to the vmbus channel.
+	 *
+	 * To eliminate the race, hv_pci_suspend() disables the channel
+	 * callback tasklet, sets hbus->state to hv_pcibus_removing, and
+	 * re-enables the tasklet. This way, when hv_pci_suspend() proceeds,
+	 * it knows that no new work item can be scheduled, and then it flushes
+	 * hbus->wq and safely closes the vmbus channel.
+	 */
+	tasklet_disable(&hdev->channel->callback_event);
+
+	/* Change the hbus state to prevent new work items. */
+	old_state = hbus->state;
+	if (hbus->state == hv_pcibus_installed)
+		hbus->state = hv_pcibus_removing;
+
+	tasklet_enable(&hdev->channel->callback_event);
+
+	if (old_state != hv_pcibus_installed)
+		return -EINVAL;
+
+	flush_workqueue(hbus->wq);
+
+	ret = hv_pci_bus_exit(hdev, true);
+	if (ret)
+		return ret;
+
+	vmbus_close(hdev->channel);
+
+	return 0;
+}
+
+static int hv_pci_restore_msi_msg(struct pci_dev *pdev, void *arg)
+{
+	struct irq_data *irq_data;
+	struct msi_desc *entry;
+	int ret = 0;
+
+	if (!pdev->msi_enabled && !pdev->msix_enabled)
+		return 0;
+
+	msi_lock_descs(&pdev->dev);
+	msi_for_each_desc(entry, &pdev->dev, MSI_DESC_ASSOCIATED) {
+		irq_data = irq_get_irq_data(entry->irq);
+		if (WARN_ON_ONCE(!irq_data)) {
+			ret = -EINVAL;
+			break;
+		}
+
+		hv_compose_msi_msg(irq_data, &entry->msg);
+	}
+	msi_unlock_descs(&pdev->dev);
+
+	return ret;
+}
+
+/*
+ * Upon resume, pci_restore_msi_state() -> ... ->  __pci_write_msi_msg()
+ * directly writes the MSI/MSI-X registers via MMIO, but since Hyper-V
+ * doesn't trap and emulate the MMIO accesses, here hv_compose_msi_msg()
+ * must be used to ask Hyper-V to re-create the IOMMU Interrupt Remapping
+ * Table entries.
+ */
+static void hv_pci_restore_msi_state(struct hv_pcibus_device *hbus)
+{
+	pci_walk_bus(hbus->bridge->bus, hv_pci_restore_msi_msg, NULL);
+}
+
+static int hv_pci_resume(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	enum pci_protocol_version_t version[1];
+	int ret;
+
+	hbus->state = hv_pcibus_init;
+
+	hdev->channel->next_request_id_callback = vmbus_next_request_id;
+	hdev->channel->request_addr_callback = vmbus_request_addr;
+	hdev->channel->rqstor_size = HV_PCI_RQSTOR_SIZE;
+
+	ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
+			 hv_pci_onchannelcallback, hbus);
+	if (ret)
+		return ret;
+
+	/* Only use the version that was in use before hibernation. */
+	version[0] = hbus->protocol_version;
+	ret = hv_pci_protocol_negotiation(hdev, version, 1);
+	if (ret)
+		goto out;
+
+	ret = hv_pci_query_relations(hdev);
+	if (ret)
+		goto out;
+
+	mutex_lock(&hbus->state_lock);
+
+	ret = hv_pci_enter_d0(hdev);
+	if (ret)
+		goto release_state_lock;
+
+	ret = hv_send_resources_allocated(hdev);
+	if (ret)
+		goto release_state_lock;
+
+	prepopulate_bars(hbus);
+
+	hv_pci_restore_msi_state(hbus);
+
+	hbus->state = hv_pcibus_installed;
+	mutex_unlock(&hbus->state_lock);
+	return 0;
+
+release_state_lock:
+	mutex_unlock(&hbus->state_lock);
+out:
+	vmbus_close(hdev->channel);
+	return ret;
+}
+
+static const struct hv_vmbus_device_id hv_pci_id_table[] = {
+	/* PCI Pass-through Class ID */
+	/* 44C4F61D-4444-4400-9D52-802E27EDE19F */
+	{ HV_PCIE_GUID, },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(vmbus, hv_pci_id_table);
+
+static struct hv_driver hv_pci_drv = {
+	.name		= "hv_pci",
+	.id_table	= hv_pci_id_table,
+	.probe		= hv_pci_probe,
+	.remove		= hv_pci_remove,
+	.suspend	= hv_pci_suspend,
+	.resume		= hv_pci_resume,
+};
+
+static void __exit exit_hv_pci_drv(void)
+{
+	vmbus_driver_unregister(&hv_pci_drv);
+
+	hvpci_block_ops.read_block = NULL;
+	hvpci_block_ops.write_block = NULL;
+	hvpci_block_ops.reg_blk_invalidate = NULL;
+}
+
+static int __init init_hv_pci_drv(void)
+{
+	int ret;
+
+	if (!hv_is_hyperv_initialized())
+		return -ENODEV;
+
+	ret = hv_pci_irqchip_init();
+	if (ret)
+		return ret;
+
+	/* Set the invalid domain number's bit, so it will not be used */
+	set_bit(HVPCI_DOM_INVALID, hvpci_dom_map);
+
+	/* Initialize PCI block r/w interface */
+	hvpci_block_ops.read_block = hv_read_config_block;
+	hvpci_block_ops.write_block = hv_write_config_block;
+	hvpci_block_ops.reg_blk_invalidate = hv_register_block_invalidate;
+
+	return vmbus_driver_register(&hv_pci_drv);
+}
+
+module_init(init_hv_pci_drv);
+module_exit(exit_hv_pci_drv);
+
+MODULE_DESCRIPTION("Hyper-V PCI");
+MODULE_LICENSE("GPL v2");