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-rw-r--r--drivers/virtio/virtio_mem.c2952
1 files changed, 2952 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
new file mode 100644
index 000000000..0c2892ec6
--- /dev/null
+++ b/drivers/virtio/virtio_mem.c
@@ -0,0 +1,2952 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio-mem device driver.
+ *
+ * Copyright Red Hat, Inc. 2020
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+
+#include <linux/virtio.h>
+#include <linux/virtio_mem.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/memory_hotplug.h>
+#include <linux/memory.h>
+#include <linux/hrtimer.h>
+#include <linux/crash_dump.h>
+#include <linux/mutex.h>
+#include <linux/bitmap.h>
+#include <linux/lockdep.h>
+#include <linux/log2.h>
+
+#include <acpi/acpi_numa.h>
+
+static bool unplug_online = true;
+module_param(unplug_online, bool, 0644);
+MODULE_PARM_DESC(unplug_online, "Try to unplug online memory");
+
+static bool force_bbm;
+module_param(force_bbm, bool, 0444);
+MODULE_PARM_DESC(force_bbm,
+ "Force Big Block Mode. Default is 0 (auto-selection)");
+
+static unsigned long bbm_block_size;
+module_param(bbm_block_size, ulong, 0444);
+MODULE_PARM_DESC(bbm_block_size,
+ "Big Block size in bytes. Default is 0 (auto-detection).");
+
+static bool bbm_safe_unplug = true;
+module_param(bbm_safe_unplug, bool, 0444);
+MODULE_PARM_DESC(bbm_safe_unplug,
+ "Use a safe unplug mechanism in BBM, avoiding long/endless loops");
+
+/*
+ * virtio-mem currently supports the following modes of operation:
+ *
+ * * Sub Block Mode (SBM): A Linux memory block spans 2..X subblocks (SB). The
+ * size of a Sub Block (SB) is determined based on the device block size, the
+ * pageblock size, and the maximum allocation granularity of the buddy.
+ * Subblocks within a Linux memory block might either be plugged or unplugged.
+ * Memory is added/removed to Linux MM in Linux memory block granularity.
+ *
+ * * Big Block Mode (BBM): A Big Block (BB) spans 1..X Linux memory blocks.
+ * Memory is added/removed to Linux MM in Big Block granularity.
+ *
+ * The mode is determined automatically based on the Linux memory block size
+ * and the device block size.
+ *
+ * User space / core MM (auto onlining) is responsible for onlining added
+ * Linux memory blocks - and for selecting a zone. Linux Memory Blocks are
+ * always onlined separately, and all memory within a Linux memory block is
+ * onlined to the same zone - virtio-mem relies on this behavior.
+ */
+
+/*
+ * State of a Linux memory block in SBM.
+ */
+enum virtio_mem_sbm_mb_state {
+ /* Unplugged, not added to Linux. Can be reused later. */
+ VIRTIO_MEM_SBM_MB_UNUSED = 0,
+ /* (Partially) plugged, not added to Linux. Error on add_memory(). */
+ VIRTIO_MEM_SBM_MB_PLUGGED,
+ /* Fully plugged, fully added to Linux, offline. */
+ VIRTIO_MEM_SBM_MB_OFFLINE,
+ /* Partially plugged, fully added to Linux, offline. */
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
+ /* Fully plugged, fully added to Linux, onlined to a kernel zone. */
+ VIRTIO_MEM_SBM_MB_KERNEL,
+ /* Partially plugged, fully added to Linux, online to a kernel zone */
+ VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
+ /* Fully plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
+ VIRTIO_MEM_SBM_MB_MOVABLE,
+ /* Partially plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
+ VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_COUNT
+};
+
+/*
+ * State of a Big Block (BB) in BBM, covering 1..X Linux memory blocks.
+ */
+enum virtio_mem_bbm_bb_state {
+ /* Unplugged, not added to Linux. Can be reused later. */
+ VIRTIO_MEM_BBM_BB_UNUSED = 0,
+ /* Plugged, not added to Linux. Error on add_memory(). */
+ VIRTIO_MEM_BBM_BB_PLUGGED,
+ /* Plugged and added to Linux. */
+ VIRTIO_MEM_BBM_BB_ADDED,
+ /* All online parts are fake-offline, ready to remove. */
+ VIRTIO_MEM_BBM_BB_FAKE_OFFLINE,
+ VIRTIO_MEM_BBM_BB_COUNT
+};
+
+struct virtio_mem {
+ struct virtio_device *vdev;
+
+ /* We might first have to unplug all memory when starting up. */
+ bool unplug_all_required;
+
+ /* Workqueue that processes the plug/unplug requests. */
+ struct work_struct wq;
+ atomic_t wq_active;
+ atomic_t config_changed;
+
+ /* Virtqueue for guest->host requests. */
+ struct virtqueue *vq;
+
+ /* Wait for a host response to a guest request. */
+ wait_queue_head_t host_resp;
+
+ /* Space for one guest request and the host response. */
+ struct virtio_mem_req req;
+ struct virtio_mem_resp resp;
+
+ /* The current size of the device. */
+ uint64_t plugged_size;
+ /* The requested size of the device. */
+ uint64_t requested_size;
+
+ /* The device block size (for communicating with the device). */
+ uint64_t device_block_size;
+ /* The determined node id for all memory of the device. */
+ int nid;
+ /* Physical start address of the memory region. */
+ uint64_t addr;
+ /* Maximum region size in bytes. */
+ uint64_t region_size;
+
+ /* The parent resource for all memory added via this device. */
+ struct resource *parent_resource;
+ /*
+ * Copy of "System RAM (virtio_mem)" to be used for
+ * add_memory_driver_managed().
+ */
+ const char *resource_name;
+ /* Memory group identification. */
+ int mgid;
+
+ /*
+ * We don't want to add too much memory if it's not getting onlined,
+ * to avoid running OOM. Besides this threshold, we allow to have at
+ * least two offline blocks at a time (whatever is bigger).
+ */
+#define VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD (1024 * 1024 * 1024)
+ atomic64_t offline_size;
+ uint64_t offline_threshold;
+
+ /* If set, the driver is in SBM, otherwise in BBM. */
+ bool in_sbm;
+
+ union {
+ struct {
+ /* Id of the first memory block of this device. */
+ unsigned long first_mb_id;
+ /* Id of the last usable memory block of this device. */
+ unsigned long last_usable_mb_id;
+ /* Id of the next memory bock to prepare when needed. */
+ unsigned long next_mb_id;
+
+ /* The subblock size. */
+ uint64_t sb_size;
+ /* The number of subblocks per Linux memory block. */
+ uint32_t sbs_per_mb;
+
+ /* Summary of all memory block states. */
+ unsigned long mb_count[VIRTIO_MEM_SBM_MB_COUNT];
+
+ /*
+ * One byte state per memory block. Allocated via
+ * vmalloc(). Resized (alloc+copy+free) on demand.
+ *
+ * With 128 MiB memory blocks, we have states for 512
+ * GiB of memory in one 4 KiB page.
+ */
+ uint8_t *mb_states;
+
+ /*
+ * Bitmap: one bit per subblock. Allocated similar to
+ * sbm.mb_states.
+ *
+ * A set bit means the corresponding subblock is
+ * plugged, otherwise it's unblocked.
+ *
+ * With 4 MiB subblocks, we manage 128 GiB of memory
+ * in one 4 KiB page.
+ */
+ unsigned long *sb_states;
+ } sbm;
+
+ struct {
+ /* Id of the first big block of this device. */
+ unsigned long first_bb_id;
+ /* Id of the last usable big block of this device. */
+ unsigned long last_usable_bb_id;
+ /* Id of the next device bock to prepare when needed. */
+ unsigned long next_bb_id;
+
+ /* Summary of all big block states. */
+ unsigned long bb_count[VIRTIO_MEM_BBM_BB_COUNT];
+
+ /* One byte state per big block. See sbm.mb_states. */
+ uint8_t *bb_states;
+
+ /* The block size used for plugging/adding/removing. */
+ uint64_t bb_size;
+ } bbm;
+ };
+
+ /*
+ * Mutex that protects the sbm.mb_count, sbm.mb_states,
+ * sbm.sb_states, bbm.bb_count, and bbm.bb_states
+ *
+ * When this lock is held the pointers can't change, ONLINE and
+ * OFFLINE blocks can't change the state and no subblocks will get
+ * plugged/unplugged.
+ *
+ * In kdump mode, used to serialize requests, last_block_addr and
+ * last_block_plugged.
+ */
+ struct mutex hotplug_mutex;
+ bool hotplug_active;
+
+ /* An error occurred we cannot handle - stop processing requests. */
+ bool broken;
+
+ /* Cached valued of is_kdump_kernel() when the device was probed. */
+ bool in_kdump;
+
+ /* The driver is being removed. */
+ spinlock_t removal_lock;
+ bool removing;
+
+ /* Timer for retrying to plug/unplug memory. */
+ struct hrtimer retry_timer;
+ unsigned int retry_timer_ms;
+#define VIRTIO_MEM_RETRY_TIMER_MIN_MS 50000
+#define VIRTIO_MEM_RETRY_TIMER_MAX_MS 300000
+
+ /* Memory notifier (online/offline events). */
+ struct notifier_block memory_notifier;
+
+#ifdef CONFIG_PROC_VMCORE
+ /* vmcore callback for /proc/vmcore handling in kdump mode */
+ struct vmcore_cb vmcore_cb;
+ uint64_t last_block_addr;
+ bool last_block_plugged;
+#endif /* CONFIG_PROC_VMCORE */
+
+ /* Next device in the list of virtio-mem devices. */
+ struct list_head next;
+};
+
+/*
+ * We have to share a single online_page callback among all virtio-mem
+ * devices. We use RCU to iterate the list in the callback.
+ */
+static DEFINE_MUTEX(virtio_mem_mutex);
+static LIST_HEAD(virtio_mem_devices);
+
+static void virtio_mem_online_page_cb(struct page *page, unsigned int order);
+static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
+ unsigned long nr_pages);
+static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
+ unsigned long nr_pages);
+static void virtio_mem_retry(struct virtio_mem *vm);
+static int virtio_mem_create_resource(struct virtio_mem *vm);
+static void virtio_mem_delete_resource(struct virtio_mem *vm);
+
+/*
+ * Register a virtio-mem device so it will be considered for the online_page
+ * callback.
+ */
+static int register_virtio_mem_device(struct virtio_mem *vm)
+{
+ int rc = 0;
+
+ /* First device registers the callback. */
+ mutex_lock(&virtio_mem_mutex);
+ if (list_empty(&virtio_mem_devices))
+ rc = set_online_page_callback(&virtio_mem_online_page_cb);
+ if (!rc)
+ list_add_rcu(&vm->next, &virtio_mem_devices);
+ mutex_unlock(&virtio_mem_mutex);
+
+ return rc;
+}
+
+/*
+ * Unregister a virtio-mem device so it will no longer be considered for the
+ * online_page callback.
+ */
+static void unregister_virtio_mem_device(struct virtio_mem *vm)
+{
+ /* Last device unregisters the callback. */
+ mutex_lock(&virtio_mem_mutex);
+ list_del_rcu(&vm->next);
+ if (list_empty(&virtio_mem_devices))
+ restore_online_page_callback(&virtio_mem_online_page_cb);
+ mutex_unlock(&virtio_mem_mutex);
+
+ synchronize_rcu();
+}
+
+/*
+ * Calculate the memory block id of a given address.
+ */
+static unsigned long virtio_mem_phys_to_mb_id(unsigned long addr)
+{
+ return addr / memory_block_size_bytes();
+}
+
+/*
+ * Calculate the physical start address of a given memory block id.
+ */
+static unsigned long virtio_mem_mb_id_to_phys(unsigned long mb_id)
+{
+ return mb_id * memory_block_size_bytes();
+}
+
+/*
+ * Calculate the big block id of a given address.
+ */
+static unsigned long virtio_mem_phys_to_bb_id(struct virtio_mem *vm,
+ uint64_t addr)
+{
+ return addr / vm->bbm.bb_size;
+}
+
+/*
+ * Calculate the physical start address of a given big block id.
+ */
+static uint64_t virtio_mem_bb_id_to_phys(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ return bb_id * vm->bbm.bb_size;
+}
+
+/*
+ * Calculate the subblock id of a given address.
+ */
+static unsigned long virtio_mem_phys_to_sb_id(struct virtio_mem *vm,
+ unsigned long addr)
+{
+ const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
+ const unsigned long mb_addr = virtio_mem_mb_id_to_phys(mb_id);
+
+ return (addr - mb_addr) / vm->sbm.sb_size;
+}
+
+/*
+ * Set the state of a big block, taking care of the state counter.
+ */
+static void virtio_mem_bbm_set_bb_state(struct virtio_mem *vm,
+ unsigned long bb_id,
+ enum virtio_mem_bbm_bb_state state)
+{
+ const unsigned long idx = bb_id - vm->bbm.first_bb_id;
+ enum virtio_mem_bbm_bb_state old_state;
+
+ old_state = vm->bbm.bb_states[idx];
+ vm->bbm.bb_states[idx] = state;
+
+ BUG_ON(vm->bbm.bb_count[old_state] == 0);
+ vm->bbm.bb_count[old_state]--;
+ vm->bbm.bb_count[state]++;
+}
+
+/*
+ * Get the state of a big block.
+ */
+static enum virtio_mem_bbm_bb_state virtio_mem_bbm_get_bb_state(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ return vm->bbm.bb_states[bb_id - vm->bbm.first_bb_id];
+}
+
+/*
+ * Prepare the big block state array for the next big block.
+ */
+static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
+{
+ unsigned long old_bytes = vm->bbm.next_bb_id - vm->bbm.first_bb_id;
+ unsigned long new_bytes = old_bytes + 1;
+ int old_pages = PFN_UP(old_bytes);
+ int new_pages = PFN_UP(new_bytes);
+ uint8_t *new_array;
+
+ if (vm->bbm.bb_states && old_pages == new_pages)
+ return 0;
+
+ new_array = vzalloc(new_pages * PAGE_SIZE);
+ if (!new_array)
+ return -ENOMEM;
+
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->bbm.bb_states)
+ memcpy(new_array, vm->bbm.bb_states, old_pages * PAGE_SIZE);
+ vfree(vm->bbm.bb_states);
+ vm->bbm.bb_states = new_array;
+ mutex_unlock(&vm->hotplug_mutex);
+
+ return 0;
+}
+
+#define virtio_mem_bbm_for_each_bb(_vm, _bb_id, _state) \
+ for (_bb_id = vm->bbm.first_bb_id; \
+ _bb_id < vm->bbm.next_bb_id && _vm->bbm.bb_count[_state]; \
+ _bb_id++) \
+ if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
+
+#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \
+ for (_bb_id = vm->bbm.next_bb_id - 1; \
+ _bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \
+ _bb_id--) \
+ if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
+
+/*
+ * Set the state of a memory block, taking care of the state counter.
+ */
+static void virtio_mem_sbm_set_mb_state(struct virtio_mem *vm,
+ unsigned long mb_id, uint8_t state)
+{
+ const unsigned long idx = mb_id - vm->sbm.first_mb_id;
+ uint8_t old_state;
+
+ old_state = vm->sbm.mb_states[idx];
+ vm->sbm.mb_states[idx] = state;
+
+ BUG_ON(vm->sbm.mb_count[old_state] == 0);
+ vm->sbm.mb_count[old_state]--;
+ vm->sbm.mb_count[state]++;
+}
+
+/*
+ * Get the state of a memory block.
+ */
+static uint8_t virtio_mem_sbm_get_mb_state(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long idx = mb_id - vm->sbm.first_mb_id;
+
+ return vm->sbm.mb_states[idx];
+}
+
+/*
+ * Prepare the state array for the next memory block.
+ */
+static int virtio_mem_sbm_mb_states_prepare_next_mb(struct virtio_mem *vm)
+{
+ int old_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id);
+ int new_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id + 1);
+ uint8_t *new_array;
+
+ if (vm->sbm.mb_states && old_pages == new_pages)
+ return 0;
+
+ new_array = vzalloc(new_pages * PAGE_SIZE);
+ if (!new_array)
+ return -ENOMEM;
+
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->sbm.mb_states)
+ memcpy(new_array, vm->sbm.mb_states, old_pages * PAGE_SIZE);
+ vfree(vm->sbm.mb_states);
+ vm->sbm.mb_states = new_array;
+ mutex_unlock(&vm->hotplug_mutex);
+
+ return 0;
+}
+
+#define virtio_mem_sbm_for_each_mb(_vm, _mb_id, _state) \
+ for (_mb_id = _vm->sbm.first_mb_id; \
+ _mb_id < _vm->sbm.next_mb_id && _vm->sbm.mb_count[_state]; \
+ _mb_id++) \
+ if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
+
+#define virtio_mem_sbm_for_each_mb_rev(_vm, _mb_id, _state) \
+ for (_mb_id = _vm->sbm.next_mb_id - 1; \
+ _mb_id >= _vm->sbm.first_mb_id && _vm->sbm.mb_count[_state]; \
+ _mb_id--) \
+ if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
+
+/*
+ * Calculate the bit number in the subblock bitmap for the given subblock
+ * inside the given memory block.
+ */
+static int virtio_mem_sbm_sb_state_bit_nr(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id)
+{
+ return (mb_id - vm->sbm.first_mb_id) * vm->sbm.sbs_per_mb + sb_id;
+}
+
+/*
+ * Mark all selected subblocks plugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_sbm_set_sb_plugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
+
+ __bitmap_set(vm->sbm.sb_states, bit, count);
+}
+
+/*
+ * Mark all selected subblocks unplugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_sbm_set_sb_unplugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
+
+ __bitmap_clear(vm->sbm.sb_states, bit, count);
+}
+
+/*
+ * Test if all selected subblocks are plugged.
+ */
+static bool virtio_mem_sbm_test_sb_plugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
+
+ if (count == 1)
+ return test_bit(bit, vm->sbm.sb_states);
+
+ /* TODO: Helper similar to bitmap_set() */
+ return find_next_zero_bit(vm->sbm.sb_states, bit + count, bit) >=
+ bit + count;
+}
+
+/*
+ * Test if all selected subblocks are unplugged.
+ */
+static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
+
+ /* TODO: Helper similar to bitmap_set() */
+ return find_next_bit(vm->sbm.sb_states, bit + count, bit) >=
+ bit + count;
+}
+
+/*
+ * Find the first unplugged subblock. Returns vm->sbm.sbs_per_mb in case there is
+ * none.
+ */
+static int virtio_mem_sbm_first_unplugged_sb(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, 0);
+
+ return find_next_zero_bit(vm->sbm.sb_states,
+ bit + vm->sbm.sbs_per_mb, bit) - bit;
+}
+
+/*
+ * Prepare the subblock bitmap for the next memory block.
+ */
+static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)
+{
+ const unsigned long old_nb_mb = vm->sbm.next_mb_id - vm->sbm.first_mb_id;
+ const unsigned long old_nb_bits = old_nb_mb * vm->sbm.sbs_per_mb;
+ const unsigned long new_nb_bits = (old_nb_mb + 1) * vm->sbm.sbs_per_mb;
+ int old_pages = PFN_UP(BITS_TO_LONGS(old_nb_bits) * sizeof(long));
+ int new_pages = PFN_UP(BITS_TO_LONGS(new_nb_bits) * sizeof(long));
+ unsigned long *new_bitmap, *old_bitmap;
+
+ if (vm->sbm.sb_states && old_pages == new_pages)
+ return 0;
+
+ new_bitmap = vzalloc(new_pages * PAGE_SIZE);
+ if (!new_bitmap)
+ return -ENOMEM;
+
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->sbm.sb_states)
+ memcpy(new_bitmap, vm->sbm.sb_states, old_pages * PAGE_SIZE);
+
+ old_bitmap = vm->sbm.sb_states;
+ vm->sbm.sb_states = new_bitmap;
+ mutex_unlock(&vm->hotplug_mutex);
+
+ vfree(old_bitmap);
+ return 0;
+}
+
+/*
+ * Test if we could add memory without creating too much offline memory -
+ * to avoid running OOM if memory is getting onlined deferred.
+ */
+static bool virtio_mem_could_add_memory(struct virtio_mem *vm, uint64_t size)
+{
+ if (WARN_ON_ONCE(size > vm->offline_threshold))
+ return false;
+
+ return atomic64_read(&vm->offline_size) + size <= vm->offline_threshold;
+}
+
+/*
+ * Try adding memory to Linux. Will usually only fail if out of memory.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of memory blocks in virtio-mem.
+ */
+static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,
+ uint64_t size)
+{
+ int rc;
+
+ /*
+ * When force-unloading the driver and we still have memory added to
+ * Linux, the resource name has to stay.
+ */
+ if (!vm->resource_name) {
+ vm->resource_name = kstrdup_const("System RAM (virtio_mem)",
+ GFP_KERNEL);
+ if (!vm->resource_name)
+ return -ENOMEM;
+ }
+
+ dev_dbg(&vm->vdev->dev, "adding memory: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+ /* Memory might get onlined immediately. */
+ atomic64_add(size, &vm->offline_size);
+ rc = add_memory_driver_managed(vm->mgid, addr, size, vm->resource_name,
+ MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);
+ if (rc) {
+ atomic64_sub(size, &vm->offline_size);
+ dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
+ /*
+ * TODO: Linux MM does not properly clean up yet in all cases
+ * where adding of memory failed - especially on -ENOMEM.
+ */
+ }
+ return rc;
+}
+
+/*
+ * See virtio_mem_add_memory(): Try adding a single Linux memory block.
+ */
+static int virtio_mem_sbm_add_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ const uint64_t size = memory_block_size_bytes();
+
+ return virtio_mem_add_memory(vm, addr, size);
+}
+
+/*
+ * See virtio_mem_add_memory(): Try adding a big block.
+ */
+static int virtio_mem_bbm_add_bb(struct virtio_mem *vm, unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_add_memory(vm, addr, size);
+}
+
+/*
+ * Try removing memory from Linux. Will only fail if memory blocks aren't
+ * offline.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of memory blocks in virtio-mem.
+ */
+static int virtio_mem_remove_memory(struct virtio_mem *vm, uint64_t addr,
+ uint64_t size)
+{
+ int rc;
+
+ dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+ rc = remove_memory(addr, size);
+ if (!rc) {
+ atomic64_sub(size, &vm->offline_size);
+ /*
+ * We might have freed up memory we can now unplug, retry
+ * immediately instead of waiting.
+ */
+ virtio_mem_retry(vm);
+ } else {
+ dev_dbg(&vm->vdev->dev, "removing memory failed: %d\n", rc);
+ }
+ return rc;
+}
+
+/*
+ * See virtio_mem_remove_memory(): Try removing a single Linux memory block.
+ */
+static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ const uint64_t size = memory_block_size_bytes();
+
+ return virtio_mem_remove_memory(vm, addr, size);
+}
+
+/*
+ * Try offlining and removing memory from Linux.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of memory blocks in virtio-mem.
+ */
+static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
+ uint64_t addr,
+ uint64_t size)
+{
+ int rc;
+
+ dev_dbg(&vm->vdev->dev,
+ "offlining and removing memory: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+
+ rc = offline_and_remove_memory(addr, size);
+ if (!rc) {
+ atomic64_sub(size, &vm->offline_size);
+ /*
+ * We might have freed up memory we can now unplug, retry
+ * immediately instead of waiting.
+ */
+ virtio_mem_retry(vm);
+ } else {
+ dev_dbg(&vm->vdev->dev,
+ "offlining and removing memory failed: %d\n", rc);
+ }
+ return rc;
+}
+
+/*
+ * See virtio_mem_offline_and_remove_memory(): Try offlining and removing
+ * a single Linux memory block.
+ */
+static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ const uint64_t size = memory_block_size_bytes();
+
+ return virtio_mem_offline_and_remove_memory(vm, addr, size);
+}
+
+/*
+ * See virtio_mem_offline_and_remove_memory(): Try to offline and remove a
+ * all Linux memory blocks covered by the big block.
+ */
+static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_offline_and_remove_memory(vm, addr, size);
+}
+
+/*
+ * Trigger the workqueue so the device can perform its magic.
+ */
+static void virtio_mem_retry(struct virtio_mem *vm)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&vm->removal_lock, flags);
+ if (!vm->removing)
+ queue_work(system_freezable_wq, &vm->wq);
+ spin_unlock_irqrestore(&vm->removal_lock, flags);
+}
+
+static int virtio_mem_translate_node_id(struct virtio_mem *vm, uint16_t node_id)
+{
+ int node = NUMA_NO_NODE;
+
+#if defined(CONFIG_ACPI_NUMA)
+ if (virtio_has_feature(vm->vdev, VIRTIO_MEM_F_ACPI_PXM))
+ node = pxm_to_node(node_id);
+#endif
+ return node;
+}
+
+/*
+ * Test if a virtio-mem device overlaps with the given range. Can be called
+ * from (notifier) callbacks lockless.
+ */
+static bool virtio_mem_overlaps_range(struct virtio_mem *vm, uint64_t start,
+ uint64_t size)
+{
+ return start < vm->addr + vm->region_size && vm->addr < start + size;
+}
+
+/*
+ * Test if a virtio-mem device contains a given range. Can be called from
+ * (notifier) callbacks lockless.
+ */
+static bool virtio_mem_contains_range(struct virtio_mem *vm, uint64_t start,
+ uint64_t size)
+{
+ return start >= vm->addr && start + size <= vm->addr + vm->region_size;
+}
+
+static int virtio_mem_sbm_notify_going_online(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
+ case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_OFFLINE:
+ return NOTIFY_OK;
+ default:
+ break;
+ }
+ dev_warn_ratelimited(&vm->vdev->dev,
+ "memory block onlining denied\n");
+ return NOTIFY_BAD;
+}
+
+static void virtio_mem_sbm_notify_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
+ case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
+ break;
+ case VIRTIO_MEM_SBM_MB_KERNEL:
+ case VIRTIO_MEM_SBM_MB_MOVABLE:
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE);
+ break;
+ default:
+ BUG();
+ break;
+ }
+}
+
+static void virtio_mem_sbm_notify_online(struct virtio_mem *vm,
+ unsigned long mb_id,
+ unsigned long start_pfn)
+{
+ const bool is_movable = is_zone_movable_page(pfn_to_page(start_pfn));
+ int new_state;
+
+ switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
+ case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
+ new_state = VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL;
+ if (is_movable)
+ new_state = VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL;
+ break;
+ case VIRTIO_MEM_SBM_MB_OFFLINE:
+ new_state = VIRTIO_MEM_SBM_MB_KERNEL;
+ if (is_movable)
+ new_state = VIRTIO_MEM_SBM_MB_MOVABLE;
+ break;
+ default:
+ BUG();
+ break;
+ }
+ virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
+}
+
+static void virtio_mem_sbm_notify_going_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
+ unsigned long pfn;
+ int sb_id;
+
+ for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
+ if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
+ continue;
+ pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size);
+ virtio_mem_fake_offline_going_offline(pfn, nr_pages);
+ }
+}
+
+static void virtio_mem_sbm_notify_cancel_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
+ unsigned long pfn;
+ int sb_id;
+
+ for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
+ if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
+ continue;
+ pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size);
+ virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
+ }
+}
+
+static void virtio_mem_bbm_notify_going_offline(struct virtio_mem *vm,
+ unsigned long bb_id,
+ unsigned long pfn,
+ unsigned long nr_pages)
+{
+ /*
+ * When marked as "fake-offline", all online memory of this device block
+ * is allocated by us. Otherwise, we don't have any memory allocated.
+ */
+ if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
+ return;
+ virtio_mem_fake_offline_going_offline(pfn, nr_pages);
+}
+
+static void virtio_mem_bbm_notify_cancel_offline(struct virtio_mem *vm,
+ unsigned long bb_id,
+ unsigned long pfn,
+ unsigned long nr_pages)
+{
+ if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
+ return;
+ virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
+}
+
+/*
+ * This callback will either be called synchronously from add_memory() or
+ * asynchronously (e.g., triggered via user space). We have to be careful
+ * with locking when calling add_memory().
+ */
+static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
+ unsigned long action, void *arg)
+{
+ struct virtio_mem *vm = container_of(nb, struct virtio_mem,
+ memory_notifier);
+ struct memory_notify *mhp = arg;
+ const unsigned long start = PFN_PHYS(mhp->start_pfn);
+ const unsigned long size = PFN_PHYS(mhp->nr_pages);
+ int rc = NOTIFY_OK;
+ unsigned long id;
+
+ if (!virtio_mem_overlaps_range(vm, start, size))
+ return NOTIFY_DONE;
+
+ if (vm->in_sbm) {
+ id = virtio_mem_phys_to_mb_id(start);
+ /*
+ * In SBM, we add memory in separate memory blocks - we expect
+ * it to be onlined/offlined in the same granularity. Bail out
+ * if this ever changes.
+ */
+ if (WARN_ON_ONCE(size != memory_block_size_bytes() ||
+ !IS_ALIGNED(start, memory_block_size_bytes())))
+ return NOTIFY_BAD;
+ } else {
+ id = virtio_mem_phys_to_bb_id(vm, start);
+ /*
+ * In BBM, we only care about onlining/offlining happening
+ * within a single big block, we don't care about the
+ * actual granularity as we don't track individual Linux
+ * memory blocks.
+ */
+ if (WARN_ON_ONCE(id != virtio_mem_phys_to_bb_id(vm, start + size - 1)))
+ return NOTIFY_BAD;
+ }
+
+ /*
+ * Avoid circular locking lockdep warnings. We lock the mutex
+ * e.g., in MEM_GOING_ONLINE and unlock it in MEM_ONLINE. The
+ * blocking_notifier_call_chain() has it's own lock, which gets unlocked
+ * between both notifier calls and will bail out. False positive.
+ */
+ lockdep_off();
+
+ switch (action) {
+ case MEM_GOING_OFFLINE:
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->removing) {
+ rc = notifier_from_errno(-EBUSY);
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ }
+ vm->hotplug_active = true;
+ if (vm->in_sbm)
+ virtio_mem_sbm_notify_going_offline(vm, id);
+ else
+ virtio_mem_bbm_notify_going_offline(vm, id,
+ mhp->start_pfn,
+ mhp->nr_pages);
+ break;
+ case MEM_GOING_ONLINE:
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->removing) {
+ rc = notifier_from_errno(-EBUSY);
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ }
+ vm->hotplug_active = true;
+ if (vm->in_sbm)
+ rc = virtio_mem_sbm_notify_going_online(vm, id);
+ break;
+ case MEM_OFFLINE:
+ if (vm->in_sbm)
+ virtio_mem_sbm_notify_offline(vm, id);
+
+ atomic64_add(size, &vm->offline_size);
+ /*
+ * Trigger the workqueue. Now that we have some offline memory,
+ * maybe we can handle pending unplug requests.
+ */
+ if (!unplug_online)
+ virtio_mem_retry(vm);
+
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ case MEM_ONLINE:
+ if (vm->in_sbm)
+ virtio_mem_sbm_notify_online(vm, id, mhp->start_pfn);
+
+ atomic64_sub(size, &vm->offline_size);
+ /*
+ * Start adding more memory once we onlined half of our
+ * threshold. Don't trigger if it's possibly due to our actipn
+ * (e.g., us adding memory which gets onlined immediately from
+ * the core).
+ */
+ if (!atomic_read(&vm->wq_active) &&
+ virtio_mem_could_add_memory(vm, vm->offline_threshold / 2))
+ virtio_mem_retry(vm);
+
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ case MEM_CANCEL_OFFLINE:
+ if (!vm->hotplug_active)
+ break;
+ if (vm->in_sbm)
+ virtio_mem_sbm_notify_cancel_offline(vm, id);
+ else
+ virtio_mem_bbm_notify_cancel_offline(vm, id,
+ mhp->start_pfn,
+ mhp->nr_pages);
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ case MEM_CANCEL_ONLINE:
+ if (!vm->hotplug_active)
+ break;
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ default:
+ break;
+ }
+
+ lockdep_on();
+
+ return rc;
+}
+
+/*
+ * Set a range of pages PG_offline. Remember pages that were never onlined
+ * (via generic_online_page()) using PageDirty().
+ */
+static void virtio_mem_set_fake_offline(unsigned long pfn,
+ unsigned long nr_pages, bool onlined)
+{
+ page_offline_begin();
+ for (; nr_pages--; pfn++) {
+ struct page *page = pfn_to_page(pfn);
+
+ __SetPageOffline(page);
+ if (!onlined) {
+ SetPageDirty(page);
+ /* FIXME: remove after cleanups */
+ ClearPageReserved(page);
+ }
+ }
+ page_offline_end();
+}
+
+/*
+ * Clear PG_offline from a range of pages. If the pages were never onlined,
+ * (via generic_online_page()), clear PageDirty().
+ */
+static void virtio_mem_clear_fake_offline(unsigned long pfn,
+ unsigned long nr_pages, bool onlined)
+{
+ for (; nr_pages--; pfn++) {
+ struct page *page = pfn_to_page(pfn);
+
+ __ClearPageOffline(page);
+ if (!onlined)
+ ClearPageDirty(page);
+ }
+}
+
+/*
+ * Release a range of fake-offline pages to the buddy, effectively
+ * fake-onlining them.
+ */
+static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
+{
+ unsigned long order = MAX_ORDER - 1;
+ unsigned long i;
+
+ /*
+ * We might get called for ranges that don't cover properly aligned
+ * MAX_ORDER - 1 pages; however, we can only online properly aligned
+ * pages with an order of MAX_ORDER - 1 at maximum.
+ */
+ while (!IS_ALIGNED(pfn | nr_pages, 1 << order))
+ order--;
+
+ for (i = 0; i < nr_pages; i += 1 << order) {
+ struct page *page = pfn_to_page(pfn + i);
+
+ /*
+ * If the page is PageDirty(), it was kept fake-offline when
+ * onlining the memory block. Otherwise, it was allocated
+ * using alloc_contig_range(). All pages in a subblock are
+ * alike.
+ */
+ if (PageDirty(page)) {
+ virtio_mem_clear_fake_offline(pfn + i, 1 << order, false);
+ generic_online_page(page, order);
+ } else {
+ virtio_mem_clear_fake_offline(pfn + i, 1 << order, true);
+ free_contig_range(pfn + i, 1 << order);
+ adjust_managed_page_count(page, 1 << order);
+ }
+ }
+}
+
+/*
+ * Try to allocate a range, marking pages fake-offline, effectively
+ * fake-offlining them.
+ */
+static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages)
+{
+ const bool is_movable = is_zone_movable_page(pfn_to_page(pfn));
+ int rc, retry_count;
+
+ /*
+ * TODO: We want an alloc_contig_range() mode that tries to allocate
+ * harder (e.g., dealing with temporarily pinned pages, PCP), especially
+ * with ZONE_MOVABLE. So for now, retry a couple of times with
+ * ZONE_MOVABLE before giving up - because that zone is supposed to give
+ * some guarantees.
+ */
+ for (retry_count = 0; retry_count < 5; retry_count++) {
+ rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
+ GFP_KERNEL);
+ if (rc == -ENOMEM)
+ /* whoops, out of memory */
+ return rc;
+ else if (rc && !is_movable)
+ break;
+ else if (rc)
+ continue;
+
+ virtio_mem_set_fake_offline(pfn, nr_pages, true);
+ adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
+ return 0;
+ }
+
+ return -EBUSY;
+}
+
+/*
+ * Handle fake-offline pages when memory is going offline - such that the
+ * pages can be skipped by mm-core when offlining.
+ */
+static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
+ unsigned long nr_pages)
+{
+ struct page *page;
+ unsigned long i;
+
+ /*
+ * Drop our reference to the pages so the memory can get offlined
+ * and add the unplugged pages to the managed page counters (so
+ * offlining code can correctly subtract them again).
+ */
+ adjust_managed_page_count(pfn_to_page(pfn), nr_pages);
+ /* Drop our reference to the pages so the memory can get offlined. */
+ for (i = 0; i < nr_pages; i++) {
+ page = pfn_to_page(pfn + i);
+ if (WARN_ON(!page_ref_dec_and_test(page)))
+ dump_page(page, "fake-offline page referenced");
+ }
+}
+
+/*
+ * Handle fake-offline pages when memory offlining is canceled - to undo
+ * what we did in virtio_mem_fake_offline_going_offline().
+ */
+static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
+ unsigned long nr_pages)
+{
+ unsigned long i;
+
+ /*
+ * Get the reference we dropped when going offline and subtract the
+ * unplugged pages from the managed page counters.
+ */
+ adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
+ for (i = 0; i < nr_pages; i++)
+ page_ref_inc(pfn_to_page(pfn + i));
+}
+
+static void virtio_mem_online_page(struct virtio_mem *vm,
+ struct page *page, unsigned int order)
+{
+ const unsigned long start = page_to_phys(page);
+ const unsigned long end = start + PFN_PHYS(1 << order);
+ unsigned long addr, next, id, sb_id, count;
+ bool do_online;
+
+ /*
+ * We can get called with any order up to MAX_ORDER - 1. If our
+ * subblock size is smaller than that and we have a mixture of plugged
+ * and unplugged subblocks within such a page, we have to process in
+ * smaller granularity. In that case we'll adjust the order exactly once
+ * within the loop.
+ */
+ for (addr = start; addr < end; ) {
+ next = addr + PFN_PHYS(1 << order);
+
+ if (vm->in_sbm) {
+ id = virtio_mem_phys_to_mb_id(addr);
+ sb_id = virtio_mem_phys_to_sb_id(vm, addr);
+ count = virtio_mem_phys_to_sb_id(vm, next - 1) - sb_id + 1;
+
+ if (virtio_mem_sbm_test_sb_plugged(vm, id, sb_id, count)) {
+ /* Fully plugged. */
+ do_online = true;
+ } else if (count == 1 ||
+ virtio_mem_sbm_test_sb_unplugged(vm, id, sb_id, count)) {
+ /* Fully unplugged. */
+ do_online = false;
+ } else {
+ /*
+ * Mixture, process sub-blocks instead. This
+ * will be at least the size of a pageblock.
+ * We'll run into this case exactly once.
+ */
+ order = ilog2(vm->sbm.sb_size) - PAGE_SHIFT;
+ do_online = virtio_mem_sbm_test_sb_plugged(vm, id, sb_id, 1);
+ continue;
+ }
+ } else {
+ /*
+ * If the whole block is marked fake offline, keep
+ * everything that way.
+ */
+ id = virtio_mem_phys_to_bb_id(vm, addr);
+ do_online = virtio_mem_bbm_get_bb_state(vm, id) !=
+ VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;
+ }
+
+ if (do_online)
+ generic_online_page(pfn_to_page(PFN_DOWN(addr)), order);
+ else
+ virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
+ false);
+ addr = next;
+ }
+}
+
+static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
+{
+ const unsigned long addr = page_to_phys(page);
+ struct virtio_mem *vm;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(vm, &virtio_mem_devices, next) {
+ /*
+ * Pages we're onlining will never cross memory blocks and,
+ * therefore, not virtio-mem devices.
+ */
+ if (!virtio_mem_contains_range(vm, addr, PFN_PHYS(1 << order)))
+ continue;
+
+ /*
+ * virtio_mem_set_fake_offline() might sleep. We can safely
+ * drop the RCU lock at this point because the device
+ * cannot go away. See virtio_mem_remove() how races
+ * between memory onlining and device removal are handled.
+ */
+ rcu_read_unlock();
+
+ virtio_mem_online_page(vm, page, order);
+ return;
+ }
+ rcu_read_unlock();
+
+ /* not virtio-mem memory, but e.g., a DIMM. online it */
+ generic_online_page(page, order);
+}
+
+static uint64_t virtio_mem_send_request(struct virtio_mem *vm,
+ const struct virtio_mem_req *req)
+{
+ struct scatterlist *sgs[2], sg_req, sg_resp;
+ unsigned int len;
+ int rc;
+
+ /* don't use the request residing on the stack (vaddr) */
+ vm->req = *req;
+
+ /* out: buffer for request */
+ sg_init_one(&sg_req, &vm->req, sizeof(vm->req));
+ sgs[0] = &sg_req;
+
+ /* in: buffer for response */
+ sg_init_one(&sg_resp, &vm->resp, sizeof(vm->resp));
+ sgs[1] = &sg_resp;
+
+ rc = virtqueue_add_sgs(vm->vq, sgs, 1, 1, vm, GFP_KERNEL);
+ if (rc < 0)
+ return rc;
+
+ virtqueue_kick(vm->vq);
+
+ /* wait for a response */
+ wait_event(vm->host_resp, virtqueue_get_buf(vm->vq, &len));
+
+ return virtio16_to_cpu(vm->vdev, vm->resp.type);
+}
+
+static int virtio_mem_send_plug_request(struct virtio_mem *vm, uint64_t addr,
+ uint64_t size)
+{
+ const uint64_t nb_vm_blocks = size / vm->device_block_size;
+ const struct virtio_mem_req req = {
+ .type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_PLUG),
+ .u.plug.addr = cpu_to_virtio64(vm->vdev, addr),
+ .u.plug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
+ };
+ int rc = -ENOMEM;
+
+ if (atomic_read(&vm->config_changed))
+ return -EAGAIN;
+
+ dev_dbg(&vm->vdev->dev, "plugging memory: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ vm->plugged_size += size;
+ return 0;
+ case VIRTIO_MEM_RESP_NACK:
+ rc = -EAGAIN;
+ break;
+ case VIRTIO_MEM_RESP_BUSY:
+ rc = -ETXTBSY;
+ break;
+ case VIRTIO_MEM_RESP_ERROR:
+ rc = -EINVAL;
+ break;
+ default:
+ break;
+ }
+
+ dev_dbg(&vm->vdev->dev, "plugging memory failed: %d\n", rc);
+ return rc;
+}
+
+static int virtio_mem_send_unplug_request(struct virtio_mem *vm, uint64_t addr,
+ uint64_t size)
+{
+ const uint64_t nb_vm_blocks = size / vm->device_block_size;
+ const struct virtio_mem_req req = {
+ .type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG),
+ .u.unplug.addr = cpu_to_virtio64(vm->vdev, addr),
+ .u.unplug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
+ };
+ int rc = -ENOMEM;
+
+ if (atomic_read(&vm->config_changed))
+ return -EAGAIN;
+
+ dev_dbg(&vm->vdev->dev, "unplugging memory: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ vm->plugged_size -= size;
+ return 0;
+ case VIRTIO_MEM_RESP_BUSY:
+ rc = -ETXTBSY;
+ break;
+ case VIRTIO_MEM_RESP_ERROR:
+ rc = -EINVAL;
+ break;
+ default:
+ break;
+ }
+
+ dev_dbg(&vm->vdev->dev, "unplugging memory failed: %d\n", rc);
+ return rc;
+}
+
+static int virtio_mem_send_unplug_all_request(struct virtio_mem *vm)
+{
+ const struct virtio_mem_req req = {
+ .type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG_ALL),
+ };
+ int rc = -ENOMEM;
+
+ dev_dbg(&vm->vdev->dev, "unplugging all memory");
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ vm->unplug_all_required = false;
+ vm->plugged_size = 0;
+ /* usable region might have shrunk */
+ atomic_set(&vm->config_changed, 1);
+ return 0;
+ case VIRTIO_MEM_RESP_BUSY:
+ rc = -ETXTBSY;
+ break;
+ default:
+ break;
+ }
+
+ dev_dbg(&vm->vdev->dev, "unplugging all memory failed: %d\n", rc);
+ return rc;
+}
+
+/*
+ * Plug selected subblocks. Updates the plugged state, but not the state
+ * of the memory block.
+ */
+static int virtio_mem_sbm_plug_sb(struct virtio_mem *vm, unsigned long mb_id,
+ int sb_id, int count)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size;
+ const uint64_t size = count * vm->sbm.sb_size;
+ int rc;
+
+ rc = virtio_mem_send_plug_request(vm, addr, size);
+ if (!rc)
+ virtio_mem_sbm_set_sb_plugged(vm, mb_id, sb_id, count);
+ return rc;
+}
+
+/*
+ * Unplug selected subblocks. Updates the plugged state, but not the state
+ * of the memory block.
+ */
+static int virtio_mem_sbm_unplug_sb(struct virtio_mem *vm, unsigned long mb_id,
+ int sb_id, int count)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size;
+ const uint64_t size = count * vm->sbm.sb_size;
+ int rc;
+
+ rc = virtio_mem_send_unplug_request(vm, addr, size);
+ if (!rc)
+ virtio_mem_sbm_set_sb_unplugged(vm, mb_id, sb_id, count);
+ return rc;
+}
+
+/*
+ * Request to unplug a big block.
+ *
+ * Will not modify the state of the big block.
+ */
+static int virtio_mem_bbm_unplug_bb(struct virtio_mem *vm, unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_send_unplug_request(vm, addr, size);
+}
+
+/*
+ * Request to plug a big block.
+ *
+ * Will not modify the state of the big block.
+ */
+static int virtio_mem_bbm_plug_bb(struct virtio_mem *vm, unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_send_plug_request(vm, addr, size);
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of a offline or not-added
+ * memory block. Will fail if any subblock cannot get unplugged (instead of
+ * skipping it).
+ *
+ * Will not modify the state of the memory block.
+ *
+ * Note: can fail after some subblocks were unplugged.
+ */
+static int virtio_mem_sbm_unplug_any_sb_raw(struct virtio_mem *vm,
+ unsigned long mb_id, uint64_t *nb_sb)
+{
+ int sb_id, count;
+ int rc;
+
+ sb_id = vm->sbm.sbs_per_mb - 1;
+ while (*nb_sb) {
+ /* Find the next candidate subblock */
+ while (sb_id >= 0 &&
+ virtio_mem_sbm_test_sb_unplugged(vm, mb_id, sb_id, 1))
+ sb_id--;
+ if (sb_id < 0)
+ break;
+ /* Try to unplug multiple subblocks at a time */
+ count = 1;
+ while (count < *nb_sb && sb_id > 0 &&
+ virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id - 1, 1)) {
+ count++;
+ sb_id--;
+ }
+
+ rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
+ if (rc)
+ return rc;
+ *nb_sb -= count;
+ sb_id--;
+ }
+
+ return 0;
+}
+
+/*
+ * Unplug all plugged subblocks of an offline or not-added memory block.
+ *
+ * Will not modify the state of the memory block.
+ *
+ * Note: can fail after some subblocks were unplugged.
+ */
+static int virtio_mem_sbm_unplug_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+ uint64_t nb_sb = vm->sbm.sbs_per_mb;
+
+ return virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, &nb_sb);
+}
+
+/*
+ * Prepare tracking data for the next memory block.
+ */
+static int virtio_mem_sbm_prepare_next_mb(struct virtio_mem *vm,
+ unsigned long *mb_id)
+{
+ int rc;
+
+ if (vm->sbm.next_mb_id > vm->sbm.last_usable_mb_id)
+ return -ENOSPC;
+
+ /* Resize the state array if required. */
+ rc = virtio_mem_sbm_mb_states_prepare_next_mb(vm);
+ if (rc)
+ return rc;
+
+ /* Resize the subblock bitmap if required. */
+ rc = virtio_mem_sbm_sb_states_prepare_next_mb(vm);
+ if (rc)
+ return rc;
+
+ vm->sbm.mb_count[VIRTIO_MEM_SBM_MB_UNUSED]++;
+ *mb_id = vm->sbm.next_mb_id++;
+ return 0;
+}
+
+/*
+ * Try to plug the desired number of subblocks and add the memory block
+ * to Linux.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_sbm_plug_and_add_mb(struct virtio_mem *vm,
+ unsigned long mb_id, uint64_t *nb_sb)
+{
+ const int count = min_t(int, *nb_sb, vm->sbm.sbs_per_mb);
+ int rc;
+
+ if (WARN_ON_ONCE(!count))
+ return -EINVAL;
+
+ /*
+ * Plug the requested number of subblocks before adding it to linux,
+ * so that onlining will directly online all plugged subblocks.
+ */
+ rc = virtio_mem_sbm_plug_sb(vm, mb_id, 0, count);
+ if (rc)
+ return rc;
+
+ /*
+ * Mark the block properly offline before adding it to Linux,
+ * so the memory notifiers will find the block in the right state.
+ */
+ if (count == vm->sbm.sbs_per_mb)
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE);
+ else
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
+
+ /* Add the memory block to linux - if that fails, try to unplug. */
+ rc = virtio_mem_sbm_add_mb(vm, mb_id);
+ if (rc) {
+ int new_state = VIRTIO_MEM_SBM_MB_UNUSED;
+
+ if (virtio_mem_sbm_unplug_sb(vm, mb_id, 0, count))
+ new_state = VIRTIO_MEM_SBM_MB_PLUGGED;
+ virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
+ return rc;
+ }
+
+ *nb_sb -= count;
+ return 0;
+}
+
+/*
+ * Try to plug the desired number of subblocks of a memory block that
+ * is already added to Linux.
+ *
+ * Will modify the state of the memory block.
+ *
+ * Note: Can fail after some subblocks were successfully plugged.
+ */
+static int virtio_mem_sbm_plug_any_sb(struct virtio_mem *vm,
+ unsigned long mb_id, uint64_t *nb_sb)
+{
+ const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
+ unsigned long pfn, nr_pages;
+ int sb_id, count;
+ int rc;
+
+ if (WARN_ON_ONCE(!*nb_sb))
+ return -EINVAL;
+
+ while (*nb_sb) {
+ sb_id = virtio_mem_sbm_first_unplugged_sb(vm, mb_id);
+ if (sb_id >= vm->sbm.sbs_per_mb)
+ break;
+ count = 1;
+ while (count < *nb_sb &&
+ sb_id + count < vm->sbm.sbs_per_mb &&
+ !virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id + count, 1))
+ count++;
+
+ rc = virtio_mem_sbm_plug_sb(vm, mb_id, sb_id, count);
+ if (rc)
+ return rc;
+ *nb_sb -= count;
+ if (old_state == VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL)
+ continue;
+
+ /* fake-online the pages if the memory block is online */
+ pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size);
+ nr_pages = PFN_DOWN(count * vm->sbm.sb_size);
+ virtio_mem_fake_online(pfn, nr_pages);
+ }
+
+ if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
+ virtio_mem_sbm_set_mb_state(vm, mb_id, old_state - 1);
+
+ return 0;
+}
+
+static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ const int mb_states[] = {
+ VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
+ VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
+ };
+ uint64_t nb_sb = diff / vm->sbm.sb_size;
+ unsigned long mb_id;
+ int rc, i;
+
+ if (!nb_sb)
+ return 0;
+
+ /* Don't race with onlining/offlining */
+ mutex_lock(&vm->hotplug_mutex);
+
+ for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
+ virtio_mem_sbm_for_each_mb(vm, mb_id, mb_states[i]) {
+ rc = virtio_mem_sbm_plug_any_sb(vm, mb_id, &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ cond_resched();
+ }
+ }
+
+ /*
+ * We won't be working on online/offline memory blocks from this point,
+ * so we can't race with memory onlining/offlining. Drop the mutex.
+ */
+ mutex_unlock(&vm->hotplug_mutex);
+
+ /* Try to plug and add unused blocks */
+ virtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_UNUSED) {
+ if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
+ return -ENOSPC;
+
+ rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
+ if (rc || !nb_sb)
+ return rc;
+ cond_resched();
+ }
+
+ /* Try to prepare, plug and add new blocks */
+ while (nb_sb) {
+ if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
+ return -ENOSPC;
+
+ rc = virtio_mem_sbm_prepare_next_mb(vm, &mb_id);
+ if (rc)
+ return rc;
+ rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
+ if (rc)
+ return rc;
+ cond_resched();
+ }
+
+ return 0;
+out_unlock:
+ mutex_unlock(&vm->hotplug_mutex);
+ return rc;
+}
+
+/*
+ * Plug a big block and add it to Linux.
+ *
+ * Will modify the state of the big block.
+ */
+static int virtio_mem_bbm_plug_and_add_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ int rc;
+
+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_UNUSED))
+ return -EINVAL;
+
+ rc = virtio_mem_bbm_plug_bb(vm, bb_id);
+ if (rc)
+ return rc;
+ virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
+
+ rc = virtio_mem_bbm_add_bb(vm, bb_id);
+ if (rc) {
+ if (!virtio_mem_bbm_unplug_bb(vm, bb_id))
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_UNUSED);
+ else
+ /* Retry from the main loop. */
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_PLUGGED);
+ return rc;
+ }
+ return 0;
+}
+
+/*
+ * Prepare tracking data for the next big block.
+ */
+static int virtio_mem_bbm_prepare_next_bb(struct virtio_mem *vm,
+ unsigned long *bb_id)
+{
+ int rc;
+
+ if (vm->bbm.next_bb_id > vm->bbm.last_usable_bb_id)
+ return -ENOSPC;
+
+ /* Resize the big block state array if required. */
+ rc = virtio_mem_bbm_bb_states_prepare_next_bb(vm);
+ if (rc)
+ return rc;
+
+ vm->bbm.bb_count[VIRTIO_MEM_BBM_BB_UNUSED]++;
+ *bb_id = vm->bbm.next_bb_id;
+ vm->bbm.next_bb_id++;
+ return 0;
+}
+
+static int virtio_mem_bbm_plug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ uint64_t nb_bb = diff / vm->bbm.bb_size;
+ unsigned long bb_id;
+ int rc;
+
+ if (!nb_bb)
+ return 0;
+
+ /* Try to plug and add unused big blocks */
+ virtio_mem_bbm_for_each_bb(vm, bb_id, VIRTIO_MEM_BBM_BB_UNUSED) {
+ if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
+ return -ENOSPC;
+
+ rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
+ if (!rc)
+ nb_bb--;
+ if (rc || !nb_bb)
+ return rc;
+ cond_resched();
+ }
+
+ /* Try to prepare, plug and add new big blocks */
+ while (nb_bb) {
+ if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
+ return -ENOSPC;
+
+ rc = virtio_mem_bbm_prepare_next_bb(vm, &bb_id);
+ if (rc)
+ return rc;
+ rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
+ if (!rc)
+ nb_bb--;
+ if (rc)
+ return rc;
+ cond_resched();
+ }
+
+ return 0;
+}
+
+/*
+ * Try to plug the requested amount of memory.
+ */
+static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ if (vm->in_sbm)
+ return virtio_mem_sbm_plug_request(vm, diff);
+ return virtio_mem_bbm_plug_request(vm, diff);
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of an offline memory block.
+ * Will fail if any subblock cannot get unplugged (instead of skipping it).
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ *
+ * Note: Can fail after some subblocks were successfully unplugged.
+ */
+static int virtio_mem_sbm_unplug_any_sb_offline(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ int rc;
+
+ rc = virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, nb_sb);
+
+ /* some subblocks might have been unplugged even on failure */
+ if (!virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
+ if (rc)
+ return rc;
+
+ if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
+ /*
+ * Remove the block from Linux - this should never fail.
+ * Hinder the block from getting onlined by marking it
+ * unplugged. Temporarily drop the mutex, so
+ * any pending GOING_ONLINE requests can be serviced/rejected.
+ */
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_UNUSED);
+
+ mutex_unlock(&vm->hotplug_mutex);
+ rc = virtio_mem_sbm_remove_mb(vm, mb_id);
+ BUG_ON(rc);
+ mutex_lock(&vm->hotplug_mutex);
+ }
+ return 0;
+}
+
+/*
+ * Unplug the given plugged subblocks of an online memory block.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_sbm_unplug_sb_online(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size) * count;
+ const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
+ unsigned long start_pfn;
+ int rc;
+
+ start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->sbm.sb_size);
+
+ rc = virtio_mem_fake_offline(start_pfn, nr_pages);
+ if (rc)
+ return rc;
+
+ /* Try to unplug the allocated memory */
+ rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
+ if (rc) {
+ /* Return the memory to the buddy. */
+ virtio_mem_fake_online(start_pfn, nr_pages);
+ return rc;
+ }
+
+ switch (old_state) {
+ case VIRTIO_MEM_SBM_MB_KERNEL:
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL);
+ break;
+ case VIRTIO_MEM_SBM_MB_MOVABLE:
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL);
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of an online memory block.
+ * Will skip subblock that are busy.
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ *
+ * Note: Can fail after some subblocks were successfully unplugged. Can
+ * return 0 even if subblocks were busy and could not get unplugged.
+ */
+static int virtio_mem_sbm_unplug_any_sb_online(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ int rc, sb_id;
+
+ /* If possible, try to unplug the complete block in one shot. */
+ if (*nb_sb >= vm->sbm.sbs_per_mb &&
+ virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
+ rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, 0,
+ vm->sbm.sbs_per_mb);
+ if (!rc) {
+ *nb_sb -= vm->sbm.sbs_per_mb;
+ goto unplugged;
+ } else if (rc != -EBUSY)
+ return rc;
+ }
+
+ /* Fallback to single subblocks. */
+ for (sb_id = vm->sbm.sbs_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
+ /* Find the next candidate subblock */
+ while (sb_id >= 0 &&
+ !virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
+ sb_id--;
+ if (sb_id < 0)
+ break;
+
+ rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, sb_id, 1);
+ if (rc == -EBUSY)
+ continue;
+ else if (rc)
+ return rc;
+ *nb_sb -= 1;
+ }
+
+unplugged:
+ /*
+ * Once all subblocks of a memory block were unplugged, offline and
+ * remove it. This will usually not fail, as no memory is in use
+ * anymore - however some other notifiers might NACK the request.
+ */
+ if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
+ mutex_unlock(&vm->hotplug_mutex);
+ rc = virtio_mem_sbm_offline_and_remove_mb(vm, mb_id);
+ mutex_lock(&vm->hotplug_mutex);
+ if (!rc)
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_UNUSED);
+ }
+
+ return 0;
+}
+
+/*
+ * Unplug the desired number of plugged subblocks of a memory block that is
+ * already added to Linux. Will skip subblock of online memory blocks that are
+ * busy (by the OS). Will fail if any subblock that's not busy cannot get
+ * unplugged.
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ *
+ * Note: Can fail after some subblocks were successfully unplugged. Can
+ * return 0 even if subblocks were busy and could not get unplugged.
+ */
+static int virtio_mem_sbm_unplug_any_sb(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
+
+ switch (old_state) {
+ case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_KERNEL:
+ case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_MOVABLE:
+ return virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, nb_sb);
+ case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_OFFLINE:
+ return virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, nb_sb);
+ }
+ return -EINVAL;
+}
+
+static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ const int mb_states[] = {
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_OFFLINE,
+ VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
+ VIRTIO_MEM_SBM_MB_MOVABLE,
+ VIRTIO_MEM_SBM_MB_KERNEL,
+ };
+ uint64_t nb_sb = diff / vm->sbm.sb_size;
+ unsigned long mb_id;
+ int rc, i;
+
+ if (!nb_sb)
+ return 0;
+
+ /*
+ * We'll drop the mutex a couple of times when it is safe to do so.
+ * This might result in some blocks switching the state (online/offline)
+ * and we could miss them in this run - we will retry again later.
+ */
+ mutex_lock(&vm->hotplug_mutex);
+
+ /*
+ * We try unplug from partially plugged blocks first, to try removing
+ * whole memory blocks along with metadata. We prioritize ZONE_MOVABLE
+ * as it's more reliable to unplug memory and remove whole memory
+ * blocks, and we don't want to trigger a zone imbalances by
+ * accidentially removing too much kernel memory.
+ */
+ for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
+ virtio_mem_sbm_for_each_mb_rev(vm, mb_id, mb_states[i]) {
+ rc = virtio_mem_sbm_unplug_any_sb(vm, mb_id, &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ mutex_unlock(&vm->hotplug_mutex);
+ cond_resched();
+ mutex_lock(&vm->hotplug_mutex);
+ }
+ if (!unplug_online && i == 1) {
+ mutex_unlock(&vm->hotplug_mutex);
+ return 0;
+ }
+ }
+
+ mutex_unlock(&vm->hotplug_mutex);
+ return nb_sb ? -EBUSY : 0;
+out_unlock:
+ mutex_unlock(&vm->hotplug_mutex);
+ return rc;
+}
+
+/*
+ * Try to offline and remove a big block from Linux and unplug it. Will fail
+ * with -EBUSY if some memory is busy and cannot get unplugged.
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ */
+static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
+ const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
+ unsigned long end_pfn = start_pfn + nr_pages;
+ unsigned long pfn;
+ struct page *page;
+ int rc;
+
+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_ADDED))
+ return -EINVAL;
+
+ if (bbm_safe_unplug) {
+ /*
+ * Start by fake-offlining all memory. Once we marked the device
+ * block as fake-offline, all newly onlined memory will
+ * automatically be kept fake-offline. Protect from concurrent
+ * onlining/offlining until we have a consistent state.
+ */
+ mutex_lock(&vm->hotplug_mutex);
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_FAKE_OFFLINE);
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ page = pfn_to_online_page(pfn);
+ if (!page)
+ continue;
+
+ rc = virtio_mem_fake_offline(pfn, PAGES_PER_SECTION);
+ if (rc) {
+ end_pfn = pfn;
+ goto rollback_safe_unplug;
+ }
+ }
+ mutex_unlock(&vm->hotplug_mutex);
+ }
+
+ rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id);
+ if (rc) {
+ if (bbm_safe_unplug) {
+ mutex_lock(&vm->hotplug_mutex);
+ goto rollback_safe_unplug;
+ }
+ return rc;
+ }
+
+ rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
+ if (rc)
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_PLUGGED);
+ else
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_UNUSED);
+ return rc;
+
+rollback_safe_unplug:
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ page = pfn_to_online_page(pfn);
+ if (!page)
+ continue;
+ virtio_mem_fake_online(pfn, PAGES_PER_SECTION);
+ }
+ virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
+ mutex_unlock(&vm->hotplug_mutex);
+ return rc;
+}
+
+/*
+ * Test if a big block is completely offline.
+ */
+static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
+ const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < start_pfn + nr_pages;
+ pfn += PAGES_PER_SECTION) {
+ if (pfn_to_online_page(pfn))
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * Test if a big block is completely onlined to ZONE_MOVABLE (or offline).
+ */
+static bool virtio_mem_bbm_bb_is_movable(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
+ const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
+ struct page *page;
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < start_pfn + nr_pages;
+ pfn += PAGES_PER_SECTION) {
+ page = pfn_to_online_page(pfn);
+ if (!page)
+ continue;
+ if (page_zonenum(page) != ZONE_MOVABLE)
+ return false;
+ }
+
+ return true;
+}
+
+static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ uint64_t nb_bb = diff / vm->bbm.bb_size;
+ uint64_t bb_id;
+ int rc, i;
+
+ if (!nb_bb)
+ return 0;
+
+ /*
+ * Try to unplug big blocks. Similar to SBM, start with offline
+ * big blocks.
+ */
+ for (i = 0; i < 3; i++) {
+ virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) {
+ cond_resched();
+
+ /*
+ * As we're holding no locks, these checks are racy,
+ * but we don't care.
+ */
+ if (i == 0 && !virtio_mem_bbm_bb_is_offline(vm, bb_id))
+ continue;
+ if (i == 1 && !virtio_mem_bbm_bb_is_movable(vm, bb_id))
+ continue;
+ rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id);
+ if (rc == -EBUSY)
+ continue;
+ if (!rc)
+ nb_bb--;
+ if (rc || !nb_bb)
+ return rc;
+ }
+ if (i == 0 && !unplug_online)
+ return 0;
+ }
+
+ return nb_bb ? -EBUSY : 0;
+}
+
+/*
+ * Try to unplug the requested amount of memory.
+ */
+static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ if (vm->in_sbm)
+ return virtio_mem_sbm_unplug_request(vm, diff);
+ return virtio_mem_bbm_unplug_request(vm, diff);
+}
+
+/*
+ * Try to unplug all blocks that couldn't be unplugged before, for example,
+ * because the hypervisor was busy.
+ */
+static int virtio_mem_unplug_pending_mb(struct virtio_mem *vm)
+{
+ unsigned long id;
+ int rc;
+
+ if (!vm->in_sbm) {
+ virtio_mem_bbm_for_each_bb(vm, id,
+ VIRTIO_MEM_BBM_BB_PLUGGED) {
+ rc = virtio_mem_bbm_unplug_bb(vm, id);
+ if (rc)
+ return rc;
+ virtio_mem_bbm_set_bb_state(vm, id,
+ VIRTIO_MEM_BBM_BB_UNUSED);
+ }
+ return 0;
+ }
+
+ virtio_mem_sbm_for_each_mb(vm, id, VIRTIO_MEM_SBM_MB_PLUGGED) {
+ rc = virtio_mem_sbm_unplug_mb(vm, id);
+ if (rc)
+ return rc;
+ virtio_mem_sbm_set_mb_state(vm, id,
+ VIRTIO_MEM_SBM_MB_UNUSED);
+ }
+
+ return 0;
+}
+
+/*
+ * Update all parts of the config that could have changed.
+ */
+static void virtio_mem_refresh_config(struct virtio_mem *vm)
+{
+ const struct range pluggable_range = mhp_get_pluggable_range(true);
+ uint64_t new_plugged_size, usable_region_size, end_addr;
+
+ /* the plugged_size is just a reflection of what _we_ did previously */
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
+ &new_plugged_size);
+ if (WARN_ON_ONCE(new_plugged_size != vm->plugged_size))
+ vm->plugged_size = new_plugged_size;
+
+ /* calculate the last usable memory block id */
+ virtio_cread_le(vm->vdev, struct virtio_mem_config,
+ usable_region_size, &usable_region_size);
+ end_addr = min(vm->addr + usable_region_size - 1,
+ pluggable_range.end);
+
+ if (vm->in_sbm) {
+ vm->sbm.last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr);
+ if (!IS_ALIGNED(end_addr + 1, memory_block_size_bytes()))
+ vm->sbm.last_usable_mb_id--;
+ } else {
+ vm->bbm.last_usable_bb_id = virtio_mem_phys_to_bb_id(vm,
+ end_addr);
+ if (!IS_ALIGNED(end_addr + 1, vm->bbm.bb_size))
+ vm->bbm.last_usable_bb_id--;
+ }
+ /*
+ * If we cannot plug any of our device memory (e.g., nothing in the
+ * usable region is addressable), the last usable memory block id will
+ * be smaller than the first usable memory block id. We'll stop
+ * attempting to add memory with -ENOSPC from our main loop.
+ */
+
+ /* see if there is a request to change the size */
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, requested_size,
+ &vm->requested_size);
+
+ dev_info(&vm->vdev->dev, "plugged size: 0x%llx", vm->plugged_size);
+ dev_info(&vm->vdev->dev, "requested size: 0x%llx", vm->requested_size);
+}
+
+/*
+ * Workqueue function for handling plug/unplug requests and config updates.
+ */
+static void virtio_mem_run_wq(struct work_struct *work)
+{
+ struct virtio_mem *vm = container_of(work, struct virtio_mem, wq);
+ uint64_t diff;
+ int rc;
+
+ if (unlikely(vm->in_kdump)) {
+ dev_warn_once(&vm->vdev->dev,
+ "unexpected workqueue run in kdump kernel\n");
+ return;
+ }
+
+ hrtimer_cancel(&vm->retry_timer);
+
+ if (vm->broken)
+ return;
+
+ atomic_set(&vm->wq_active, 1);
+retry:
+ rc = 0;
+
+ /* Make sure we start with a clean state if there are leftovers. */
+ if (unlikely(vm->unplug_all_required))
+ rc = virtio_mem_send_unplug_all_request(vm);
+
+ if (atomic_read(&vm->config_changed)) {
+ atomic_set(&vm->config_changed, 0);
+ virtio_mem_refresh_config(vm);
+ }
+
+ /* Unplug any leftovers from previous runs */
+ if (!rc)
+ rc = virtio_mem_unplug_pending_mb(vm);
+
+ if (!rc && vm->requested_size != vm->plugged_size) {
+ if (vm->requested_size > vm->plugged_size) {
+ diff = vm->requested_size - vm->plugged_size;
+ rc = virtio_mem_plug_request(vm, diff);
+ } else {
+ diff = vm->plugged_size - vm->requested_size;
+ rc = virtio_mem_unplug_request(vm, diff);
+ }
+ }
+
+ switch (rc) {
+ case 0:
+ vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
+ break;
+ case -ENOSPC:
+ /*
+ * We cannot add any more memory (alignment, physical limit)
+ * or we have too many offline memory blocks.
+ */
+ break;
+ case -ETXTBSY:
+ /*
+ * The hypervisor cannot process our request right now
+ * (e.g., out of memory, migrating);
+ */
+ case -EBUSY:
+ /*
+ * We cannot free up any memory to unplug it (all plugged memory
+ * is busy).
+ */
+ case -ENOMEM:
+ /* Out of memory, try again later. */
+ hrtimer_start(&vm->retry_timer, ms_to_ktime(vm->retry_timer_ms),
+ HRTIMER_MODE_REL);
+ break;
+ case -EAGAIN:
+ /* Retry immediately (e.g., the config changed). */
+ goto retry;
+ default:
+ /* Unknown error, mark as broken */
+ dev_err(&vm->vdev->dev,
+ "unknown error, marking device broken: %d\n", rc);
+ vm->broken = true;
+ }
+
+ atomic_set(&vm->wq_active, 0);
+}
+
+static enum hrtimer_restart virtio_mem_timer_expired(struct hrtimer *timer)
+{
+ struct virtio_mem *vm = container_of(timer, struct virtio_mem,
+ retry_timer);
+
+ virtio_mem_retry(vm);
+ vm->retry_timer_ms = min_t(unsigned int, vm->retry_timer_ms * 2,
+ VIRTIO_MEM_RETRY_TIMER_MAX_MS);
+ return HRTIMER_NORESTART;
+}
+
+static void virtio_mem_handle_response(struct virtqueue *vq)
+{
+ struct virtio_mem *vm = vq->vdev->priv;
+
+ wake_up(&vm->host_resp);
+}
+
+static int virtio_mem_init_vq(struct virtio_mem *vm)
+{
+ struct virtqueue *vq;
+
+ vq = virtio_find_single_vq(vm->vdev, virtio_mem_handle_response,
+ "guest-request");
+ if (IS_ERR(vq))
+ return PTR_ERR(vq);
+ vm->vq = vq;
+
+ return 0;
+}
+
+static int virtio_mem_init_hotplug(struct virtio_mem *vm)
+{
+ const struct range pluggable_range = mhp_get_pluggable_range(true);
+ uint64_t unit_pages, sb_size, addr;
+ int rc;
+
+ /* bad device setup - warn only */
+ if (!IS_ALIGNED(vm->addr, memory_block_size_bytes()))
+ dev_warn(&vm->vdev->dev,
+ "The alignment of the physical start address can make some memory unusable.\n");
+ if (!IS_ALIGNED(vm->addr + vm->region_size, memory_block_size_bytes()))
+ dev_warn(&vm->vdev->dev,
+ "The alignment of the physical end address can make some memory unusable.\n");
+ if (vm->addr < pluggable_range.start ||
+ vm->addr + vm->region_size - 1 > pluggable_range.end)
+ dev_warn(&vm->vdev->dev,
+ "Some device memory is not addressable/pluggable. This can make some memory unusable.\n");
+
+ /* Prepare the offline threshold - make sure we can add two blocks. */
+ vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(),
+ VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
+
+ /*
+ * alloc_contig_range() works reliably with pageblock
+ * granularity on ZONE_NORMAL, use pageblock_nr_pages.
+ */
+ sb_size = PAGE_SIZE * pageblock_nr_pages;
+ sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
+
+ if (sb_size < memory_block_size_bytes() && !force_bbm) {
+ /* SBM: At least two subblocks per Linux memory block. */
+ vm->in_sbm = true;
+ vm->sbm.sb_size = sb_size;
+ vm->sbm.sbs_per_mb = memory_block_size_bytes() /
+ vm->sbm.sb_size;
+
+ /* Round up to the next full memory block */
+ addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
+ memory_block_size_bytes() - 1;
+ vm->sbm.first_mb_id = virtio_mem_phys_to_mb_id(addr);
+ vm->sbm.next_mb_id = vm->sbm.first_mb_id;
+ } else {
+ /* BBM: At least one Linux memory block. */
+ vm->bbm.bb_size = max_t(uint64_t, vm->device_block_size,
+ memory_block_size_bytes());
+
+ if (bbm_block_size) {
+ if (!is_power_of_2(bbm_block_size)) {
+ dev_warn(&vm->vdev->dev,
+ "bbm_block_size is not a power of 2");
+ } else if (bbm_block_size < vm->bbm.bb_size) {
+ dev_warn(&vm->vdev->dev,
+ "bbm_block_size is too small");
+ } else {
+ vm->bbm.bb_size = bbm_block_size;
+ }
+ }
+
+ /* Round up to the next aligned big block */
+ addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
+ vm->bbm.bb_size - 1;
+ vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, addr);
+ vm->bbm.next_bb_id = vm->bbm.first_bb_id;
+
+ /* Make sure we can add two big blocks. */
+ vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size,
+ vm->offline_threshold);
+ }
+
+ dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
+ memory_block_size_bytes());
+ if (vm->in_sbm)
+ dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
+ (unsigned long long)vm->sbm.sb_size);
+ else
+ dev_info(&vm->vdev->dev, "big block size: 0x%llx",
+ (unsigned long long)vm->bbm.bb_size);
+
+ /* create the parent resource for all memory */
+ rc = virtio_mem_create_resource(vm);
+ if (rc)
+ return rc;
+
+ /* use a single dynamic memory group to cover the whole memory device */
+ if (vm->in_sbm)
+ unit_pages = PHYS_PFN(memory_block_size_bytes());
+ else
+ unit_pages = PHYS_PFN(vm->bbm.bb_size);
+ rc = memory_group_register_dynamic(vm->nid, unit_pages);
+ if (rc < 0)
+ goto out_del_resource;
+ vm->mgid = rc;
+
+ /*
+ * If we still have memory plugged, we have to unplug all memory first.
+ * Registering our parent resource makes sure that this memory isn't
+ * actually in use (e.g., trying to reload the driver).
+ */
+ if (vm->plugged_size) {
+ vm->unplug_all_required = true;
+ dev_info(&vm->vdev->dev, "unplugging all memory is required\n");
+ }
+
+ /* register callbacks */
+ vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
+ rc = register_memory_notifier(&vm->memory_notifier);
+ if (rc)
+ goto out_unreg_group;
+ rc = register_virtio_mem_device(vm);
+ if (rc)
+ goto out_unreg_mem;
+
+ return 0;
+out_unreg_mem:
+ unregister_memory_notifier(&vm->memory_notifier);
+out_unreg_group:
+ memory_group_unregister(vm->mgid);
+out_del_resource:
+ virtio_mem_delete_resource(vm);
+ return rc;
+}
+
+#ifdef CONFIG_PROC_VMCORE
+static int virtio_mem_send_state_request(struct virtio_mem *vm, uint64_t addr,
+ uint64_t size)
+{
+ const uint64_t nb_vm_blocks = size / vm->device_block_size;
+ const struct virtio_mem_req req = {
+ .type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_STATE),
+ .u.state.addr = cpu_to_virtio64(vm->vdev, addr),
+ .u.state.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
+ };
+ int rc = -ENOMEM;
+
+ dev_dbg(&vm->vdev->dev, "requesting state: 0x%llx - 0x%llx\n", addr,
+ addr + size - 1);
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ return virtio16_to_cpu(vm->vdev, vm->resp.u.state.state);
+ case VIRTIO_MEM_RESP_ERROR:
+ rc = -EINVAL;
+ break;
+ default:
+ break;
+ }
+
+ dev_dbg(&vm->vdev->dev, "requesting state failed: %d\n", rc);
+ return rc;
+}
+
+static bool virtio_mem_vmcore_pfn_is_ram(struct vmcore_cb *cb,
+ unsigned long pfn)
+{
+ struct virtio_mem *vm = container_of(cb, struct virtio_mem,
+ vmcore_cb);
+ uint64_t addr = PFN_PHYS(pfn);
+ bool is_ram;
+ int rc;
+
+ if (!virtio_mem_contains_range(vm, addr, PAGE_SIZE))
+ return true;
+ if (!vm->plugged_size)
+ return false;
+
+ /*
+ * We have to serialize device requests and access to the information
+ * about the block queried last.
+ */
+ mutex_lock(&vm->hotplug_mutex);
+
+ addr = ALIGN_DOWN(addr, vm->device_block_size);
+ if (addr != vm->last_block_addr) {
+ rc = virtio_mem_send_state_request(vm, addr,
+ vm->device_block_size);
+ /* On any kind of error, we're going to signal !ram. */
+ if (rc == VIRTIO_MEM_STATE_PLUGGED)
+ vm->last_block_plugged = true;
+ else
+ vm->last_block_plugged = false;
+ vm->last_block_addr = addr;
+ }
+
+ is_ram = vm->last_block_plugged;
+ mutex_unlock(&vm->hotplug_mutex);
+ return is_ram;
+}
+#endif /* CONFIG_PROC_VMCORE */
+
+static int virtio_mem_init_kdump(struct virtio_mem *vm)
+{
+#ifdef CONFIG_PROC_VMCORE
+ dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
+ vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
+ register_vmcore_cb(&vm->vmcore_cb);
+ return 0;
+#else /* CONFIG_PROC_VMCORE */
+ dev_warn(&vm->vdev->dev, "disabled in kdump kernel without vmcore\n");
+ return -EBUSY;
+#endif /* CONFIG_PROC_VMCORE */
+}
+
+static int virtio_mem_init(struct virtio_mem *vm)
+{
+ uint16_t node_id;
+
+ if (!vm->vdev->config->get) {
+ dev_err(&vm->vdev->dev, "config access disabled\n");
+ return -EINVAL;
+ }
+
+ /* Fetch all properties that can't change. */
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
+ &vm->plugged_size);
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, block_size,
+ &vm->device_block_size);
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, node_id,
+ &node_id);
+ vm->nid = virtio_mem_translate_node_id(vm, node_id);
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, addr, &vm->addr);
+ virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
+ &vm->region_size);
+
+ /* Determine the nid for the device based on the lowest address. */
+ if (vm->nid == NUMA_NO_NODE)
+ vm->nid = memory_add_physaddr_to_nid(vm->addr);
+
+ dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr);
+ dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size);
+ dev_info(&vm->vdev->dev, "device block size: 0x%llx",
+ (unsigned long long)vm->device_block_size);
+ if (vm->nid != NUMA_NO_NODE && IS_ENABLED(CONFIG_NUMA))
+ dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
+
+ /*
+ * We don't want to (un)plug or reuse any memory when in kdump. The
+ * memory is still accessible (but not exposed to Linux).
+ */
+ if (vm->in_kdump)
+ return virtio_mem_init_kdump(vm);
+ return virtio_mem_init_hotplug(vm);
+}
+
+static int virtio_mem_create_resource(struct virtio_mem *vm)
+{
+ /*
+ * When force-unloading the driver and removing the device, we
+ * could have a garbage pointer. Duplicate the string.
+ */
+ const char *name = kstrdup(dev_name(&vm->vdev->dev), GFP_KERNEL);
+
+ if (!name)
+ return -ENOMEM;
+
+ /* Disallow mapping device memory via /dev/mem completely. */
+ vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
+ name, IORESOURCE_SYSTEM_RAM |
+ IORESOURCE_EXCLUSIVE);
+ if (!vm->parent_resource) {
+ kfree(name);
+ dev_warn(&vm->vdev->dev, "could not reserve device region\n");
+ dev_info(&vm->vdev->dev,
+ "reloading the driver is not supported\n");
+ return -EBUSY;
+ }
+
+ /* The memory is not actually busy - make add_memory() work. */
+ vm->parent_resource->flags &= ~IORESOURCE_BUSY;
+ return 0;
+}
+
+static void virtio_mem_delete_resource(struct virtio_mem *vm)
+{
+ const char *name;
+
+ if (!vm->parent_resource)
+ return;
+
+ name = vm->parent_resource->name;
+ release_resource(vm->parent_resource);
+ kfree(vm->parent_resource);
+ kfree(name);
+ vm->parent_resource = NULL;
+}
+
+static int virtio_mem_range_has_system_ram(struct resource *res, void *arg)
+{
+ return 1;
+}
+
+static bool virtio_mem_has_memory_added(struct virtio_mem *vm)
+{
+ const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+
+ return walk_iomem_res_desc(IORES_DESC_NONE, flags, vm->addr,
+ vm->addr + vm->region_size, NULL,
+ virtio_mem_range_has_system_ram) == 1;
+}
+
+static int virtio_mem_probe(struct virtio_device *vdev)
+{
+ struct virtio_mem *vm;
+ int rc;
+
+ BUILD_BUG_ON(sizeof(struct virtio_mem_req) != 24);
+ BUILD_BUG_ON(sizeof(struct virtio_mem_resp) != 10);
+
+ vdev->priv = vm = kzalloc(sizeof(*vm), GFP_KERNEL);
+ if (!vm)
+ return -ENOMEM;
+
+ init_waitqueue_head(&vm->host_resp);
+ vm->vdev = vdev;
+ INIT_WORK(&vm->wq, virtio_mem_run_wq);
+ mutex_init(&vm->hotplug_mutex);
+ INIT_LIST_HEAD(&vm->next);
+ spin_lock_init(&vm->removal_lock);
+ hrtimer_init(&vm->retry_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ vm->retry_timer.function = virtio_mem_timer_expired;
+ vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
+ vm->in_kdump = is_kdump_kernel();
+
+ /* register the virtqueue */
+ rc = virtio_mem_init_vq(vm);
+ if (rc)
+ goto out_free_vm;
+
+ /* initialize the device by querying the config */
+ rc = virtio_mem_init(vm);
+ if (rc)
+ goto out_del_vq;
+
+ virtio_device_ready(vdev);
+
+ /* trigger a config update to start processing the requested_size */
+ if (!vm->in_kdump) {
+ atomic_set(&vm->config_changed, 1);
+ queue_work(system_freezable_wq, &vm->wq);
+ }
+
+ return 0;
+out_del_vq:
+ vdev->config->del_vqs(vdev);
+out_free_vm:
+ kfree(vm);
+ vdev->priv = NULL;
+
+ return rc;
+}
+
+static void virtio_mem_deinit_hotplug(struct virtio_mem *vm)
+{
+ unsigned long mb_id;
+ int rc;
+
+ /*
+ * Make sure the workqueue won't be triggered anymore and no memory
+ * blocks can be onlined/offlined until we're finished here.
+ */
+ mutex_lock(&vm->hotplug_mutex);
+ spin_lock_irq(&vm->removal_lock);
+ vm->removing = true;
+ spin_unlock_irq(&vm->removal_lock);
+ mutex_unlock(&vm->hotplug_mutex);
+
+ /* wait until the workqueue stopped */
+ cancel_work_sync(&vm->wq);
+ hrtimer_cancel(&vm->retry_timer);
+
+ if (vm->in_sbm) {
+ /*
+ * After we unregistered our callbacks, user space can online
+ * partially plugged offline blocks. Make sure to remove them.
+ */
+ virtio_mem_sbm_for_each_mb(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL) {
+ rc = virtio_mem_sbm_remove_mb(vm, mb_id);
+ BUG_ON(rc);
+ virtio_mem_sbm_set_mb_state(vm, mb_id,
+ VIRTIO_MEM_SBM_MB_UNUSED);
+ }
+ /*
+ * After we unregistered our callbacks, user space can no longer
+ * offline partially plugged online memory blocks. No need to
+ * worry about them.
+ */
+ }
+
+ /* unregister callbacks */
+ unregister_virtio_mem_device(vm);
+ unregister_memory_notifier(&vm->memory_notifier);
+
+ /*
+ * There is no way we could reliably remove all memory we have added to
+ * the system. And there is no way to stop the driver/device from going
+ * away. Warn at least.
+ */
+ if (virtio_mem_has_memory_added(vm)) {
+ dev_warn(&vm->vdev->dev,
+ "device still has system memory added\n");
+ } else {
+ virtio_mem_delete_resource(vm);
+ kfree_const(vm->resource_name);
+ memory_group_unregister(vm->mgid);
+ }
+
+ /* remove all tracking data - no locking needed */
+ if (vm->in_sbm) {
+ vfree(vm->sbm.mb_states);
+ vfree(vm->sbm.sb_states);
+ } else {
+ vfree(vm->bbm.bb_states);
+ }
+}
+
+static void virtio_mem_deinit_kdump(struct virtio_mem *vm)
+{
+#ifdef CONFIG_PROC_VMCORE
+ unregister_vmcore_cb(&vm->vmcore_cb);
+#endif /* CONFIG_PROC_VMCORE */
+}
+
+static void virtio_mem_remove(struct virtio_device *vdev)
+{
+ struct virtio_mem *vm = vdev->priv;
+
+ if (vm->in_kdump)
+ virtio_mem_deinit_kdump(vm);
+ else
+ virtio_mem_deinit_hotplug(vm);
+
+ /* reset the device and cleanup the queues */
+ virtio_reset_device(vdev);
+ vdev->config->del_vqs(vdev);
+
+ kfree(vm);
+ vdev->priv = NULL;
+}
+
+static void virtio_mem_config_changed(struct virtio_device *vdev)
+{
+ struct virtio_mem *vm = vdev->priv;
+
+ if (unlikely(vm->in_kdump))
+ return;
+
+ atomic_set(&vm->config_changed, 1);
+ virtio_mem_retry(vm);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int virtio_mem_freeze(struct virtio_device *vdev)
+{
+ /*
+ * When restarting the VM, all memory is usually unplugged. Don't
+ * allow to suspend/hibernate.
+ */
+ dev_err(&vdev->dev, "save/restore not supported.\n");
+ return -EPERM;
+}
+
+static int virtio_mem_restore(struct virtio_device *vdev)
+{
+ return -EPERM;
+}
+#endif
+
+static unsigned int virtio_mem_features[] = {
+#if defined(CONFIG_NUMA) && defined(CONFIG_ACPI_NUMA)
+ VIRTIO_MEM_F_ACPI_PXM,
+#endif
+ VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE,
+};
+
+static const struct virtio_device_id virtio_mem_id_table[] = {
+ { VIRTIO_ID_MEM, VIRTIO_DEV_ANY_ID },
+ { 0 },
+};
+
+static struct virtio_driver virtio_mem_driver = {
+ .feature_table = virtio_mem_features,
+ .feature_table_size = ARRAY_SIZE(virtio_mem_features),
+ .driver.name = KBUILD_MODNAME,
+ .driver.owner = THIS_MODULE,
+ .id_table = virtio_mem_id_table,
+ .probe = virtio_mem_probe,
+ .remove = virtio_mem_remove,
+ .config_changed = virtio_mem_config_changed,
+#ifdef CONFIG_PM_SLEEP
+ .freeze = virtio_mem_freeze,
+ .restore = virtio_mem_restore,
+#endif
+};
+
+module_virtio_driver(virtio_mem_driver);
+MODULE_DEVICE_TABLE(virtio, virtio_mem_id_table);
+MODULE_AUTHOR("David Hildenbrand <david@redhat.com>");
+MODULE_DESCRIPTION("Virtio-mem driver");
+MODULE_LICENSE("GPL");