1 files changed, 443 insertions, 0 deletions

diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
new file mode 100644
index 000000000..84e014490
--- /dev/null
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -0,0 +1,443 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI Backend Operations - respond to PCI requests from Frontend
+ *
+ *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define dev_fmt pr_fmt
+
+#include <linux/moduleparam.h>
+#include <linux/wait.h>
+#include <linux/bitops.h>
+#include <xen/events.h>
+#include <linux/sched.h>
+#include "pciback.h"
+
+static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id);
+
+/* Ensure a device is has the fake IRQ handler "turned on/off" and is
+ * ready to be exported. This MUST be run after xen_pcibk_reset_device
+ * which does the actual PCI device enable/disable.
+ */
+static void xen_pcibk_control_isr(struct pci_dev *dev, int reset)
+{
+	struct xen_pcibk_dev_data *dev_data;
+	int rc;
+	int enable = 0;
+
+	dev_data = pci_get_drvdata(dev);
+	if (!dev_data)
+		return;
+
+	/* We don't deal with bridges */
+	if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
+		return;
+
+	if (reset) {
+		dev_data->enable_intx = 0;
+		dev_data->ack_intr = 0;
+	}
+	enable =  dev_data->enable_intx;
+
+	/* Asked to disable, but ISR isn't runnig */
+	if (!enable && !dev_data->isr_on)
+		return;
+
+	/* Squirrel away the IRQs in the dev_data. We need this
+	 * b/c when device transitions to MSI, the dev->irq is
+	 * overwritten with the MSI vector.
+	 */
+	if (enable)
+		dev_data->irq = dev->irq;
+
+	/*
+	 * SR-IOV devices in all use MSI-X and have no legacy
+	 * interrupts, so inhibit creating a fake IRQ handler for them.
+	 */
+	if (dev_data->irq == 0)
+		goto out;
+
+	dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
+		dev_data->irq_name,
+		dev_data->irq,
+		pci_is_enabled(dev) ? "on" : "off",
+		dev->msi_enabled ? "MSI" : "",
+		dev->msix_enabled ? "MSI/X" : "",
+		dev_data->isr_on ? "enable" : "disable",
+		enable ? "enable" : "disable");
+
+	if (enable) {
+		/*
+		 * The MSI or MSI-X should not have an IRQ handler. Otherwise
+		 * if the guest terminates we BUG_ON in free_msi_irqs.
+		 */
+		if (dev->msi_enabled || dev->msix_enabled)
+			goto out;
+
+		rc = request_irq(dev_data->irq,
+				xen_pcibk_guest_interrupt, IRQF_SHARED,
+				dev_data->irq_name, dev);
+		if (rc) {
+			dev_err(&dev->dev, "%s: failed to install fake IRQ " \
+				"handler for IRQ %d! (rc:%d)\n",
+				dev_data->irq_name, dev_data->irq, rc);
+			goto out;
+		}
+	} else {
+		free_irq(dev_data->irq, dev);
+		dev_data->irq = 0;
+	}
+	dev_data->isr_on = enable;
+	dev_data->ack_intr = enable;
+out:
+	dev_dbg(&dev->dev, "%s: #%d %s %s%s %s\n",
+		dev_data->irq_name,
+		dev_data->irq,
+		pci_is_enabled(dev) ? "on" : "off",
+		dev->msi_enabled ? "MSI" : "",
+		dev->msix_enabled ? "MSI/X" : "",
+		enable ? (dev_data->isr_on ? "enabled" : "failed to enable") :
+			(dev_data->isr_on ? "failed to disable" : "disabled"));
+}
+
+/* Ensure a device is "turned off" and ready to be exported.
+ * (Also see xen_pcibk_config_reset to ensure virtual configuration space is
+ * ready to be re-exported)
+ */
+void xen_pcibk_reset_device(struct pci_dev *dev)
+{
+	u16 cmd;
+
+	xen_pcibk_control_isr(dev, 1 /* reset device */);
+
+	/* Disable devices (but not bridges) */
+	if (dev->hdr_type == PCI_HEADER_TYPE_NORMAL) {
+#ifdef CONFIG_PCI_MSI
+		/* The guest could have been abruptly killed without
+		 * disabling MSI/MSI-X interrupts.*/
+		if (dev->msix_enabled)
+			pci_disable_msix(dev);
+		if (dev->msi_enabled)
+			pci_disable_msi(dev);
+#endif
+		if (pci_is_enabled(dev))
+			pci_disable_device(dev);
+
+		dev->is_busmaster = 0;
+	} else {
+		pci_read_config_word(dev, PCI_COMMAND, &cmd);
+		if (cmd & (PCI_COMMAND_INVALIDATE)) {
+			cmd &= ~(PCI_COMMAND_INVALIDATE);
+			pci_write_config_word(dev, PCI_COMMAND, cmd);
+
+			dev->is_busmaster = 0;
+		}
+	}
+}
+
+#ifdef CONFIG_PCI_MSI
+static
+int xen_pcibk_enable_msi(struct xen_pcibk_device *pdev,
+			 struct pci_dev *dev, struct xen_pci_op *op)
+{
+	struct xen_pcibk_dev_data *dev_data;
+	int status;
+
+	if (dev->msi_enabled)
+		status = -EALREADY;
+	else if (dev->msix_enabled)
+		status = -ENXIO;
+	else
+		status = pci_enable_msi(dev);
+
+	if (status) {
+		dev_warn_ratelimited(&dev->dev, "error enabling MSI for guest %u: err %d\n",
+				     pdev->xdev->otherend_id, status);
+		op->value = 0;
+		return XEN_PCI_ERR_op_failed;
+	}
+
+	/* The value the guest needs is actually the IDT vector, not
+	 * the local domain's IRQ number. */
+
+	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
+
+	dev_dbg(&dev->dev, "MSI: %d\n", op->value);
+
+	dev_data = pci_get_drvdata(dev);
+	if (dev_data)
+		dev_data->ack_intr = 0;
+
+	return 0;
+}
+
+static
+int xen_pcibk_disable_msi(struct xen_pcibk_device *pdev,
+			  struct pci_dev *dev, struct xen_pci_op *op)
+{
+	if (dev->msi_enabled) {
+		struct xen_pcibk_dev_data *dev_data;
+
+		pci_disable_msi(dev);
+
+		dev_data = pci_get_drvdata(dev);
+		if (dev_data)
+			dev_data->ack_intr = 1;
+	}
+	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
+
+	dev_dbg(&dev->dev, "MSI: %d\n", op->value);
+
+	return 0;
+}
+
+static
+int xen_pcibk_enable_msix(struct xen_pcibk_device *pdev,
+			  struct pci_dev *dev, struct xen_pci_op *op)
+{
+	struct xen_pcibk_dev_data *dev_data;
+	int i, result;
+	struct msix_entry *entries;
+	u16 cmd;
+
+	dev_dbg(&dev->dev, "enable MSI-X\n");
+
+	if (op->value > SH_INFO_MAX_VEC)
+		return -EINVAL;
+
+	if (dev->msix_enabled)
+		return -EALREADY;
+
+	/*
+	 * PCI_COMMAND_MEMORY must be enabled, otherwise we may not be able
+	 * to access the BARs where the MSI-X entries reside.
+	 * But VF devices are unique in which the PF needs to be checked.
+	 */
+	pci_read_config_word(pci_physfn(dev), PCI_COMMAND, &cmd);
+	if (dev->msi_enabled || !(cmd & PCI_COMMAND_MEMORY))
+		return -ENXIO;
+
+	entries = kmalloc_array(op->value, sizeof(*entries), GFP_KERNEL);
+	if (entries == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < op->value; i++) {
+		entries[i].entry = op->msix_entries[i].entry;
+		entries[i].vector = op->msix_entries[i].vector;
+	}
+
+	result = pci_enable_msix_exact(dev, entries, op->value);
+	if (result == 0) {
+		for (i = 0; i < op->value; i++) {
+			op->msix_entries[i].entry = entries[i].entry;
+			if (entries[i].vector) {
+				op->msix_entries[i].vector =
+					xen_pirq_from_irq(entries[i].vector);
+				dev_dbg(&dev->dev, "MSI-X[%d]: %d\n", i,
+					op->msix_entries[i].vector);
+			}
+		}
+	} else
+		dev_warn_ratelimited(&dev->dev, "error enabling MSI-X for guest %u: err %d!\n",
+				     pdev->xdev->otherend_id, result);
+	kfree(entries);
+
+	op->value = result;
+	dev_data = pci_get_drvdata(dev);
+	if (dev_data)
+		dev_data->ack_intr = 0;
+
+	return result > 0 ? 0 : result;
+}
+
+static
+int xen_pcibk_disable_msix(struct xen_pcibk_device *pdev,
+			   struct pci_dev *dev, struct xen_pci_op *op)
+{
+	if (dev->msix_enabled) {
+		struct xen_pcibk_dev_data *dev_data;
+
+		pci_disable_msix(dev);
+
+		dev_data = pci_get_drvdata(dev);
+		if (dev_data)
+			dev_data->ack_intr = 1;
+	}
+	/*
+	 * SR-IOV devices (which don't have any legacy IRQ) have
+	 * an undefined IRQ value of zero.
+	 */
+	op->value = dev->irq ? xen_pirq_from_irq(dev->irq) : 0;
+
+	dev_dbg(&dev->dev, "MSI-X: %d\n", op->value);
+
+	return 0;
+}
+#endif
+
+static inline bool xen_pcibk_test_op_pending(struct xen_pcibk_device *pdev)
+{
+	return test_bit(_XEN_PCIF_active,
+			(unsigned long *)&pdev->sh_info->flags) &&
+	       !test_and_set_bit(_PDEVF_op_active, &pdev->flags);
+}
+
+/*
+* Now the same evtchn is used for both pcifront conf_read_write request
+* as well as pcie aer front end ack. We use a new work_queue to schedule
+* xen_pcibk conf_read_write service for avoiding confict with aer_core
+* do_recovery job which also use the system default work_queue
+*/
+static void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
+{
+	bool eoi = true;
+
+	/* Check that frontend is requesting an operation and that we are not
+	 * already processing a request */
+	if (xen_pcibk_test_op_pending(pdev)) {
+		schedule_work(&pdev->op_work);
+		eoi = false;
+	}
+	/*_XEN_PCIB_active should have been cleared by pcifront. And also make
+	sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
+	if (!test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
+	    && test_bit(_PCIB_op_pending, &pdev->flags)) {
+		wake_up(&xen_pcibk_aer_wait_queue);
+		eoi = false;
+	}
+
+	/* EOI if there was nothing to do. */
+	if (eoi)
+		xen_pcibk_lateeoi(pdev, XEN_EOI_FLAG_SPURIOUS);
+}
+
+/* Performing the configuration space reads/writes must not be done in atomic
+ * context because some of the pci_* functions can sleep (mostly due to ACPI
+ * use of semaphores). This function is intended to be called from a work
+ * queue in process context taking a struct xen_pcibk_device as a parameter */
+
+static void xen_pcibk_do_one_op(struct xen_pcibk_device *pdev)
+{
+	struct pci_dev *dev;
+	struct xen_pcibk_dev_data *dev_data = NULL;
+	struct xen_pci_op *op = &pdev->op;
+	int test_intx = 0;
+#ifdef CONFIG_PCI_MSI
+	unsigned int nr = 0;
+#endif
+
+	*op = pdev->sh_info->op;
+	barrier();
+	dev = xen_pcibk_get_pci_dev(pdev, op->domain, op->bus, op->devfn);
+
+	if (dev == NULL)
+		op->err = XEN_PCI_ERR_dev_not_found;
+	else {
+		dev_data = pci_get_drvdata(dev);
+		if (dev_data)
+			test_intx = dev_data->enable_intx;
+		switch (op->cmd) {
+		case XEN_PCI_OP_conf_read:
+			op->err = xen_pcibk_config_read(dev,
+				  op->offset, op->size, &op->value);
+			break;
+		case XEN_PCI_OP_conf_write:
+			op->err = xen_pcibk_config_write(dev,
+				  op->offset, op->size,	op->value);
+			break;
+#ifdef CONFIG_PCI_MSI
+		case XEN_PCI_OP_enable_msi:
+			op->err = xen_pcibk_enable_msi(pdev, dev, op);
+			break;
+		case XEN_PCI_OP_disable_msi:
+			op->err = xen_pcibk_disable_msi(pdev, dev, op);
+			break;
+		case XEN_PCI_OP_enable_msix:
+			nr = op->value;
+			op->err = xen_pcibk_enable_msix(pdev, dev, op);
+			break;
+		case XEN_PCI_OP_disable_msix:
+			op->err = xen_pcibk_disable_msix(pdev, dev, op);
+			break;
+#endif
+		default:
+			op->err = XEN_PCI_ERR_not_implemented;
+			break;
+		}
+	}
+	if (!op->err && dev && dev_data) {
+		/* Transition detected */
+		if ((dev_data->enable_intx != test_intx))
+			xen_pcibk_control_isr(dev, 0 /* no reset */);
+	}
+	pdev->sh_info->op.err = op->err;
+	pdev->sh_info->op.value = op->value;
+#ifdef CONFIG_PCI_MSI
+	if (op->cmd == XEN_PCI_OP_enable_msix && op->err == 0) {
+		unsigned int i;
+
+		for (i = 0; i < nr; i++)
+			pdev->sh_info->op.msix_entries[i].vector =
+				op->msix_entries[i].vector;
+	}
+#endif
+	/* Tell the driver domain that we're done. */
+	wmb();
+	clear_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
+	notify_remote_via_irq(pdev->evtchn_irq);
+
+	/* Mark that we're done. */
+	smp_mb__before_atomic(); /* /after/ clearing PCIF_active */
+	clear_bit(_PDEVF_op_active, &pdev->flags);
+	smp_mb__after_atomic(); /* /before/ final check for work */
+}
+
+void xen_pcibk_do_op(struct work_struct *data)
+{
+	struct xen_pcibk_device *pdev =
+		container_of(data, struct xen_pcibk_device, op_work);
+
+	do {
+		xen_pcibk_do_one_op(pdev);
+	} while (xen_pcibk_test_op_pending(pdev));
+
+	xen_pcibk_lateeoi(pdev, 0);
+}
+
+irqreturn_t xen_pcibk_handle_event(int irq, void *dev_id)
+{
+	struct xen_pcibk_device *pdev = dev_id;
+	bool eoi;
+
+	/* IRQs might come in before pdev->evtchn_irq is written. */
+	if (unlikely(pdev->evtchn_irq != irq))
+		pdev->evtchn_irq = irq;
+
+	eoi = test_and_set_bit(_EOI_pending, &pdev->flags);
+	WARN(eoi, "IRQ while EOI pending\n");
+
+	xen_pcibk_test_and_schedule_op(pdev);
+
+	return IRQ_HANDLED;
+}
+static irqreturn_t xen_pcibk_guest_interrupt(int irq, void *dev_id)
+{
+	struct pci_dev *dev = (struct pci_dev *)dev_id;
+	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
+
+	if (dev_data->isr_on && dev_data->ack_intr) {
+		dev_data->handled++;
+		if ((dev_data->handled % 1000) == 0) {
+			if (xen_test_irq_shared(irq)) {
+				dev_info(&dev->dev, "%s IRQ line is not shared "
+					"with other domains. Turning ISR off\n",
+					 dev_data->irq_name);
+				dev_data->ack_intr = 0;
+			}
+		}
+		return IRQ_HANDLED;
+	}
+	return IRQ_NONE;
+}