Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
new file mode 100644
index 0000000..181e2f1
--- /dev/null
+++ b/drivers/virtio/virtio_mem.c
@@ -0,0 +1,1954 @@
+// 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 <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");
+
+enum virtio_mem_mb_state {
+ /* Unplugged, not added to Linux. Can be reused later. */
+ VIRTIO_MEM_MB_STATE_UNUSED = 0,
+ /* (Partially) plugged, not added to Linux. Error on add_memory(). */
+ VIRTIO_MEM_MB_STATE_PLUGGED,
+ /* Fully plugged, fully added to Linux, offline. */
+ VIRTIO_MEM_MB_STATE_OFFLINE,
+ /* Partially plugged, fully added to Linux, offline. */
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL,
+ /* Fully plugged, fully added to Linux, online. */
+ VIRTIO_MEM_MB_STATE_ONLINE,
+ /* Partially plugged, fully added to Linux, online. */
+ VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL,
+ VIRTIO_MEM_MB_STATE_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 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 translated node id. NUMA_NO_NODE in case not specified. */
+ int nid;
+ /* Physical start address of the memory region. */
+ uint64_t addr;
+ /* Maximum region size in bytes. */
+ uint64_t region_size;
+
+ /* The subblock size. */
+ uint64_t subblock_size;
+ /* The number of subblocks per memory block. */
+ uint32_t nb_sb_per_mb;
+
+ /* Id of the first memory block of this device. */
+ unsigned long first_mb_id;
+ /* Id of the last memory block of this device. */
+ unsigned long last_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 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;
+
+ /* Summary of all memory block states. */
+ unsigned long nb_mb_state[VIRTIO_MEM_MB_STATE_COUNT];
+#define VIRTIO_MEM_NB_OFFLINE_THRESHOLD 10
+
+ /*
+ * One byte state per memory block.
+ *
+ * Allocated via vmalloc(). When preparing new blocks, resized
+ * (alloc+copy+free) when needed (crossing pages with the next mb).
+ * (when crossing pages).
+ *
+ * With 128MB memory blocks, we have states for 512GB of memory in one
+ * page.
+ */
+ uint8_t *mb_state;
+
+ /*
+ * $nb_sb_per_mb bit per memory block. Handled similar to mb_state.
+ *
+ * With 4MB subblocks, we manage 128GB of memory in one page.
+ */
+ unsigned long *sb_bitmap;
+
+ /*
+ * Mutex that protects the nb_mb_state, mb_state, and sb_bitmap.
+ *
+ * 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.
+ */
+ struct mutex hotplug_mutex;
+ bool hotplug_active;
+
+ /* An error occurred we cannot handle - stop processing requests. */
+ bool broken;
+
+ /* 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;
+
+ /* 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);
+
+/*
+ * 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 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->subblock_size;
+}
+
+/*
+ * Set the state of a memory block, taking care of the state counter.
+ */
+static void virtio_mem_mb_set_state(struct virtio_mem *vm, unsigned long mb_id,
+ enum virtio_mem_mb_state state)
+{
+ const unsigned long idx = mb_id - vm->first_mb_id;
+ enum virtio_mem_mb_state old_state;
+
+ old_state = vm->mb_state[idx];
+ vm->mb_state[idx] = state;
+
+ BUG_ON(vm->nb_mb_state[old_state] == 0);
+ vm->nb_mb_state[old_state]--;
+ vm->nb_mb_state[state]++;
+}
+
+/*
+ * Get the state of a memory block.
+ */
+static enum virtio_mem_mb_state virtio_mem_mb_get_state(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long idx = mb_id - vm->first_mb_id;
+
+ return vm->mb_state[idx];
+}
+
+/*
+ * Prepare the state array for the next memory block.
+ */
+static int virtio_mem_mb_state_prepare_next_mb(struct virtio_mem *vm)
+{
+ unsigned long old_bytes = vm->next_mb_id - vm->first_mb_id + 1;
+ unsigned long new_bytes = vm->next_mb_id - vm->first_mb_id + 2;
+ int old_pages = PFN_UP(old_bytes);
+ int new_pages = PFN_UP(new_bytes);
+ uint8_t *new_mb_state;
+
+ if (vm->mb_state && old_pages == new_pages)
+ return 0;
+
+ new_mb_state = vzalloc(new_pages * PAGE_SIZE);
+ if (!new_mb_state)
+ return -ENOMEM;
+
+ mutex_lock(&vm->hotplug_mutex);
+ if (vm->mb_state)
+ memcpy(new_mb_state, vm->mb_state, old_pages * PAGE_SIZE);
+ vfree(vm->mb_state);
+ vm->mb_state = new_mb_state;
+ mutex_unlock(&vm->hotplug_mutex);
+
+ return 0;
+}
+
+#define virtio_mem_for_each_mb_state(_vm, _mb_id, _state) \
+ for (_mb_id = _vm->first_mb_id; \
+ _mb_id < _vm->next_mb_id && _vm->nb_mb_state[_state]; \
+ _mb_id++) \
+ if (virtio_mem_mb_get_state(_vm, _mb_id) == _state)
+
+#define virtio_mem_for_each_mb_state_rev(_vm, _mb_id, _state) \
+ for (_mb_id = _vm->next_mb_id - 1; \
+ _mb_id >= _vm->first_mb_id && _vm->nb_mb_state[_state]; \
+ _mb_id--) \
+ if (virtio_mem_mb_get_state(_vm, _mb_id) == _state)
+
+/*
+ * Mark all selected subblocks plugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_mb_set_sb_plugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+ __bitmap_set(vm->sb_bitmap, bit, count);
+}
+
+/*
+ * Mark all selected subblocks unplugged.
+ *
+ * Will not modify the state of the memory block.
+ */
+static void virtio_mem_mb_set_sb_unplugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+ __bitmap_clear(vm->sb_bitmap, bit, count);
+}
+
+/*
+ * Test if all selected subblocks are plugged.
+ */
+static bool virtio_mem_mb_test_sb_plugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+ if (count == 1)
+ return test_bit(bit, vm->sb_bitmap);
+
+ /* TODO: Helper similar to bitmap_set() */
+ return find_next_zero_bit(vm->sb_bitmap, bit + count, bit) >=
+ bit + count;
+}
+
+/*
+ * Test if all selected subblocks are unplugged.
+ */
+static bool virtio_mem_mb_test_sb_unplugged(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+
+ /* TODO: Helper similar to bitmap_set() */
+ return find_next_bit(vm->sb_bitmap, bit + count, bit) >= bit + count;
+}
+
+/*
+ * Find the first unplugged subblock. Returns vm->nb_sb_per_mb in case there is
+ * none.
+ */
+static int virtio_mem_mb_first_unplugged_sb(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb;
+
+ return find_next_zero_bit(vm->sb_bitmap, bit + vm->nb_sb_per_mb, bit) -
+ bit;
+}
+
+/*
+ * Prepare the subblock bitmap for the next memory block.
+ */
+static int virtio_mem_sb_bitmap_prepare_next_mb(struct virtio_mem *vm)
+{
+ const unsigned long old_nb_mb = vm->next_mb_id - vm->first_mb_id;
+ const unsigned long old_nb_bits = old_nb_mb * vm->nb_sb_per_mb;
+ const unsigned long new_nb_bits = (old_nb_mb + 1) * vm->nb_sb_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_sb_bitmap, *old_sb_bitmap;
+
+ if (vm->sb_bitmap && old_pages == new_pages)
+ return 0;
+
+ new_sb_bitmap = vzalloc(new_pages * PAGE_SIZE);
+ if (!new_sb_bitmap)
+ return -ENOMEM;
+
+ mutex_lock(&vm->hotplug_mutex);
+ if (new_sb_bitmap)
+ memcpy(new_sb_bitmap, vm->sb_bitmap, old_pages * PAGE_SIZE);
+
+ old_sb_bitmap = vm->sb_bitmap;
+ vm->sb_bitmap = new_sb_bitmap;
+ mutex_unlock(&vm->hotplug_mutex);
+
+ vfree(old_sb_bitmap);
+ return 0;
+}
+
+/*
+ * Try to add a memory block to Linux. This 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 the memory block.
+ */
+static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ int nid = vm->nid;
+
+ if (nid == NUMA_NO_NODE)
+ nid = memory_add_physaddr_to_nid(addr);
+
+ /*
+ * 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 block: %lu\n", mb_id);
+ return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
+ vm->resource_name,
+ MEMHP_MERGE_RESOURCE);
+}
+
+/*
+ * Try to remove a memory block from Linux. Will only fail if the memory block
+ * is not offline.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of the memory block.
+ */
+static int virtio_mem_mb_remove(struct virtio_mem *vm, unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ int nid = vm->nid;
+
+ if (nid == NUMA_NO_NODE)
+ nid = memory_add_physaddr_to_nid(addr);
+
+ dev_dbg(&vm->vdev->dev, "removing memory block: %lu\n", mb_id);
+ return remove_memory(nid, addr, memory_block_size_bytes());
+}
+
+/*
+ * Try to offline and remove a memory block from Linux.
+ *
+ * Must not be called with the vm->hotplug_mutex held (possible deadlock with
+ * onlining code).
+ *
+ * Will not modify the state of the memory block.
+ */
+static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+ int nid = vm->nid;
+
+ if (nid == NUMA_NO_NODE)
+ nid = memory_add_physaddr_to_nid(addr);
+
+ dev_dbg(&vm->vdev->dev, "offlining and removing memory block: %lu\n",
+ mb_id);
+ return offline_and_remove_memory(nid, addr, memory_block_size_bytes());
+}
+
+/*
+ * 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,
+ unsigned long start, unsigned long size)
+{
+ unsigned long dev_start = virtio_mem_mb_id_to_phys(vm->first_mb_id);
+ unsigned long dev_end = virtio_mem_mb_id_to_phys(vm->last_mb_id) +
+ memory_block_size_bytes();
+
+ return start < dev_end && dev_start < start + size;
+}
+
+/*
+ * Test if a virtio-mem device owns a memory block. Can be called from
+ * (notifier) callbacks lockless.
+ */
+static bool virtio_mem_owned_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+ return mb_id >= vm->first_mb_id && mb_id <= vm->last_mb_id;
+}
+
+static int virtio_mem_notify_going_online(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ switch (virtio_mem_mb_get_state(vm, mb_id)) {
+ case VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL:
+ case VIRTIO_MEM_MB_STATE_OFFLINE:
+ return NOTIFY_OK;
+ default:
+ break;
+ }
+ dev_warn_ratelimited(&vm->vdev->dev,
+ "memory block onlining denied\n");
+ return NOTIFY_BAD;
+}
+
+static void virtio_mem_notify_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ switch (virtio_mem_mb_get_state(vm, mb_id)) {
+ case VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL:
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+ break;
+ case VIRTIO_MEM_MB_STATE_ONLINE:
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE);
+ break;
+ default:
+ BUG();
+ break;
+ }
+
+ /*
+ * Trigger the workqueue, maybe we can now unplug memory. Also,
+ * when we offline and remove a memory block, this will re-trigger
+ * us immediately - which is often nice because the removal of
+ * the memory block (e.g., memmap) might have freed up memory
+ * on other memory blocks we manage.
+ */
+ virtio_mem_retry(vm);
+}
+
+static void virtio_mem_notify_online(struct virtio_mem *vm, unsigned long mb_id)
+{
+ unsigned long nb_offline;
+
+ switch (virtio_mem_mb_get_state(vm, mb_id)) {
+ case VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL:
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
+ break;
+ case VIRTIO_MEM_MB_STATE_OFFLINE:
+ virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_ONLINE);
+ break;
+ default:
+ BUG();
+ break;
+ }
+ nb_offline = vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] +
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL];
+
+ /* see if we can add new blocks now that we onlined one block */
+ if (nb_offline == VIRTIO_MEM_NB_OFFLINE_THRESHOLD - 1)
+ virtio_mem_retry(vm);
+}
+
+static void virtio_mem_notify_going_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->subblock_size);
+ struct page *page;
+ unsigned long pfn;
+ int sb_id, i;
+
+ for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) {
+ if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+ continue;
+ /*
+ * 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).
+ */
+ pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->subblock_size);
+ adjust_managed_page_count(pfn_to_page(pfn), nr_pages);
+ 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, "unplugged page referenced");
+ }
+ }
+}
+
+static void virtio_mem_notify_cancel_offline(struct virtio_mem *vm,
+ unsigned long mb_id)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->subblock_size);
+ unsigned long pfn;
+ int sb_id, i;
+
+ for (sb_id = 0; sb_id < vm->nb_sb_per_mb; sb_id++) {
+ if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+ continue;
+ /*
+ * Get the reference we dropped when going offline and
+ * subtract the unplugged pages from the managed page
+ * counters.
+ */
+ pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->subblock_size);
+ 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));
+ }
+}
+
+/*
+ * 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);
+ const unsigned long mb_id = virtio_mem_phys_to_mb_id(start);
+ int rc = NOTIFY_OK;
+
+ if (!virtio_mem_overlaps_range(vm, start, size))
+ return NOTIFY_DONE;
+
+ /*
+ * Memory is onlined/offlined in memory block granularity. We cannot
+ * cross virtio-mem device boundaries and memory block boundaries. 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;
+
+ /*
+ * 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;
+ virtio_mem_notify_going_offline(vm, mb_id);
+ 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;
+ rc = virtio_mem_notify_going_online(vm, mb_id);
+ break;
+ case MEM_OFFLINE:
+ virtio_mem_notify_offline(vm, mb_id);
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ case MEM_ONLINE:
+ virtio_mem_notify_online(vm, mb_id);
+ vm->hotplug_active = false;
+ mutex_unlock(&vm->hotplug_mutex);
+ break;
+ case MEM_CANCEL_OFFLINE:
+ if (!vm->hotplug_active)
+ break;
+ virtio_mem_notify_cancel_offline(vm, mb_id);
+ 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 int nr_pages, bool onlined)
+{
+ for (; nr_pages--; pfn++) {
+ struct page *page = pfn_to_page(pfn);
+
+ __SetPageOffline(page);
+ if (!onlined) {
+ SetPageDirty(page);
+ /* FIXME: remove after cleanups */
+ ClearPageReserved(page);
+ }
+ }
+}
+
+/*
+ * 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 int 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 int nr_pages)
+{
+ const int order = MAX_ORDER - 1;
+ int i;
+
+ /*
+ * We are always called with subblock granularity, which is at least
+ * aligned to MAX_ORDER - 1.
+ */
+ 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);
+ }
+ }
+}
+
+static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
+{
+ const unsigned long addr = page_to_phys(page);
+ const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
+ struct virtio_mem *vm;
+ int sb_id;
+
+ /*
+ * We exploit here that subblocks have at least MAX_ORDER - 1
+ * size/alignment and that this callback is is called with such a
+ * size/alignment. So we cannot cross subblocks and therefore
+ * also not memory blocks.
+ */
+ rcu_read_lock();
+ list_for_each_entry_rcu(vm, &virtio_mem_devices, next) {
+ if (!virtio_mem_owned_mb(vm, mb_id))
+ continue;
+
+ sb_id = virtio_mem_phys_to_sb_id(vm, addr);
+ /*
+ * If plugged, online the pages, otherwise, set them fake
+ * offline (PageOffline).
+ */
+ if (virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+ generic_online_page(page, order);
+ else
+ virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
+ false);
+ rcu_read_unlock();
+ 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),
+ };
+
+ if (atomic_read(&vm->config_changed))
+ return -EAGAIN;
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ vm->plugged_size += size;
+ return 0;
+ case VIRTIO_MEM_RESP_NACK:
+ return -EAGAIN;
+ case VIRTIO_MEM_RESP_BUSY:
+ return -ETXTBSY;
+ case VIRTIO_MEM_RESP_ERROR:
+ return -EINVAL;
+ default:
+ return -ENOMEM;
+ }
+}
+
+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),
+ };
+
+ if (atomic_read(&vm->config_changed))
+ return -EAGAIN;
+
+ switch (virtio_mem_send_request(vm, &req)) {
+ case VIRTIO_MEM_RESP_ACK:
+ vm->plugged_size -= size;
+ return 0;
+ case VIRTIO_MEM_RESP_BUSY:
+ return -ETXTBSY;
+ case VIRTIO_MEM_RESP_ERROR:
+ return -EINVAL;
+ default:
+ return -ENOMEM;
+ }
+}
+
+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),
+ };
+
+ 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:
+ return -ETXTBSY;
+ default:
+ return -ENOMEM;
+ }
+}
+
+/*
+ * Plug selected subblocks. Updates the plugged state, but not the state
+ * of the memory block.
+ */
+static int virtio_mem_mb_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->subblock_size;
+ const uint64_t size = count * vm->subblock_size;
+ int rc;
+
+ dev_dbg(&vm->vdev->dev, "plugging memory block: %lu : %i - %i\n", mb_id,
+ sb_id, sb_id + count - 1);
+
+ rc = virtio_mem_send_plug_request(vm, addr, size);
+ if (!rc)
+ virtio_mem_mb_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_mb_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->subblock_size;
+ const uint64_t size = count * vm->subblock_size;
+ int rc;
+
+ dev_dbg(&vm->vdev->dev, "unplugging memory block: %lu : %i - %i\n",
+ mb_id, sb_id, sb_id + count - 1);
+
+ rc = virtio_mem_send_unplug_request(vm, addr, size);
+ if (!rc)
+ virtio_mem_mb_set_sb_unplugged(vm, mb_id, sb_id, count);
+ return rc;
+}
+
+/*
+ * 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_mb_unplug_any_sb(struct virtio_mem *vm,
+ unsigned long mb_id, uint64_t *nb_sb)
+{
+ int sb_id, count;
+ int rc;
+
+ sb_id = vm->nb_sb_per_mb - 1;
+ while (*nb_sb) {
+ /* Find the next candidate subblock */
+ while (sb_id >= 0 &&
+ virtio_mem_mb_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_mb_test_sb_plugged(vm, mb_id, sb_id - 1, 1)) {
+ count++;
+ sb_id--;
+ }
+
+ rc = virtio_mem_mb_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_mb_unplug(struct virtio_mem *vm, unsigned long mb_id)
+{
+ uint64_t nb_sb = vm->nb_sb_per_mb;
+
+ return virtio_mem_mb_unplug_any_sb(vm, mb_id, &nb_sb);
+}
+
+/*
+ * Prepare tracking data for the next memory block.
+ */
+static int virtio_mem_prepare_next_mb(struct virtio_mem *vm,
+ unsigned long *mb_id)
+{
+ int rc;
+
+ if (vm->next_mb_id > vm->last_usable_mb_id)
+ return -ENOSPC;
+
+ /* Resize the state array if required. */
+ rc = virtio_mem_mb_state_prepare_next_mb(vm);
+ if (rc)
+ return rc;
+
+ /* Resize the subblock bitmap if required. */
+ rc = virtio_mem_sb_bitmap_prepare_next_mb(vm);
+ if (rc)
+ return rc;
+
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_UNUSED]++;
+ *mb_id = vm->next_mb_id++;
+ return 0;
+}
+
+/*
+ * Don't add too many blocks that are not onlined yet to avoid running OOM.
+ */
+static bool virtio_mem_too_many_mb_offline(struct virtio_mem *vm)
+{
+ unsigned long nb_offline;
+
+ nb_offline = vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] +
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL];
+ return nb_offline >= VIRTIO_MEM_NB_OFFLINE_THRESHOLD;
+}
+
+/*
+ * 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_mb_plug_and_add(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ const int count = min_t(int, *nb_sb, vm->nb_sb_per_mb);
+ int rc, rc2;
+
+ 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_mb_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->nb_sb_per_mb)
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE);
+ else
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+
+ /* Add the memory block to linux - if that fails, try to unplug. */
+ rc = virtio_mem_mb_add(vm, mb_id);
+ if (rc) {
+ enum virtio_mem_mb_state new_state = VIRTIO_MEM_MB_STATE_UNUSED;
+
+ dev_err(&vm->vdev->dev,
+ "adding memory block %lu failed with %d\n", mb_id, rc);
+ rc2 = virtio_mem_mb_unplug_sb(vm, mb_id, 0, count);
+
+ /*
+ * TODO: Linux MM does not properly clean up yet in all cases
+ * where adding of memory failed - especially on -ENOMEM.
+ */
+ if (rc2)
+ new_state = VIRTIO_MEM_MB_STATE_PLUGGED;
+ virtio_mem_mb_set_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_mb_plug_any_sb(struct virtio_mem *vm, unsigned long mb_id,
+ uint64_t *nb_sb, bool online)
+{
+ 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_mb_first_unplugged_sb(vm, mb_id);
+ if (sb_id >= vm->nb_sb_per_mb)
+ break;
+ count = 1;
+ while (count < *nb_sb &&
+ sb_id + count < vm->nb_sb_per_mb &&
+ !virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id + count,
+ 1))
+ count++;
+
+ rc = virtio_mem_mb_plug_sb(vm, mb_id, sb_id, count);
+ if (rc)
+ return rc;
+ *nb_sb -= count;
+ if (!online)
+ 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->subblock_size);
+ nr_pages = PFN_DOWN(count * vm->subblock_size);
+ virtio_mem_fake_online(pfn, nr_pages);
+ }
+
+ if (virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+ if (online)
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE);
+ else
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE);
+ }
+
+ return 0;
+}
+
+/*
+ * Try to plug the requested amount of memory.
+ */
+static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ uint64_t nb_sb = diff / vm->subblock_size;
+ unsigned long mb_id;
+ int rc;
+
+ if (!nb_sb)
+ return 0;
+
+ /* Don't race with onlining/offlining */
+ mutex_lock(&vm->hotplug_mutex);
+
+ /* Try to plug subblocks of partially plugged online blocks. */
+ virtio_mem_for_each_mb_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL) {
+ rc = virtio_mem_mb_plug_any_sb(vm, mb_id, &nb_sb, true);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ cond_resched();
+ }
+
+ /* Try to plug subblocks of partially plugged offline blocks. */
+ virtio_mem_for_each_mb_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+ rc = virtio_mem_mb_plug_any_sb(vm, mb_id, &nb_sb, false);
+ 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_for_each_mb_state(vm, mb_id, VIRTIO_MEM_MB_STATE_UNUSED) {
+ if (virtio_mem_too_many_mb_offline(vm))
+ return -ENOSPC;
+
+ rc = virtio_mem_mb_plug_and_add(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_too_many_mb_offline(vm))
+ return -ENOSPC;
+
+ rc = virtio_mem_prepare_next_mb(vm, &mb_id);
+ if (rc)
+ return rc;
+ rc = virtio_mem_mb_plug_and_add(vm, mb_id, &nb_sb);
+ if (rc)
+ return rc;
+ cond_resched();
+ }
+
+ return 0;
+out_unlock:
+ mutex_unlock(&vm->hotplug_mutex);
+ return rc;
+}
+
+/*
+ * 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_mb_unplug_any_sb_offline(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ int rc;
+
+ rc = virtio_mem_mb_unplug_any_sb(vm, mb_id, nb_sb);
+
+ /* some subblocks might have been unplugged even on failure */
+ if (!virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb))
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL);
+ if (rc)
+ return rc;
+
+ if (virtio_mem_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_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_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_UNUSED);
+
+ mutex_unlock(&vm->hotplug_mutex);
+ rc = virtio_mem_mb_remove(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_mb_unplug_sb_online(struct virtio_mem *vm,
+ unsigned long mb_id, int sb_id,
+ int count)
+{
+ const unsigned long nr_pages = PFN_DOWN(vm->subblock_size) * count;
+ unsigned long start_pfn;
+ int rc;
+
+ start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
+ sb_id * vm->subblock_size);
+ rc = alloc_contig_range(start_pfn, start_pfn + nr_pages,
+ MIGRATE_MOVABLE, GFP_KERNEL);
+ if (rc == -ENOMEM)
+ /* whoops, out of memory */
+ return rc;
+ if (rc)
+ return -EBUSY;
+
+ /* Mark it as fake-offline before unplugging it */
+ virtio_mem_set_fake_offline(start_pfn, nr_pages, true);
+ adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
+
+ /* Try to unplug the allocated memory */
+ rc = virtio_mem_mb_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;
+ }
+
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL);
+ 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_mb_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->nb_sb_per_mb &&
+ virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+ rc = virtio_mem_mb_unplug_sb_online(vm, mb_id, 0,
+ vm->nb_sb_per_mb);
+ if (!rc) {
+ *nb_sb -= vm->nb_sb_per_mb;
+ goto unplugged;
+ } else if (rc != -EBUSY)
+ return rc;
+ }
+
+ /* Fallback to single subblocks. */
+ for (sb_id = vm->nb_sb_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
+ /* Find the next candidate subblock */
+ while (sb_id >= 0 &&
+ !virtio_mem_mb_test_sb_plugged(vm, mb_id, sb_id, 1))
+ sb_id--;
+ if (sb_id < 0)
+ break;
+
+ rc = virtio_mem_mb_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_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_per_mb)) {
+ mutex_unlock(&vm->hotplug_mutex);
+ rc = virtio_mem_mb_offline_and_remove(vm, mb_id);
+ mutex_lock(&vm->hotplug_mutex);
+ if (!rc)
+ virtio_mem_mb_set_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_UNUSED);
+ }
+
+ return 0;
+}
+
+/*
+ * Try to unplug the requested amount of memory.
+ */
+static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
+{
+ uint64_t nb_sb = diff / vm->subblock_size;
+ unsigned long mb_id;
+ int rc;
+
+ 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);
+
+ /* Try to unplug subblocks of partially plugged offline blocks. */
+ virtio_mem_for_each_mb_state_rev(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+ rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id,
+ &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ cond_resched();
+ }
+
+ /* Try to unplug subblocks of plugged offline blocks. */
+ virtio_mem_for_each_mb_state_rev(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE) {
+ rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id,
+ &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ cond_resched();
+ }
+
+ if (!unplug_online) {
+ mutex_unlock(&vm->hotplug_mutex);
+ return 0;
+ }
+
+ /* Try to unplug subblocks of partially plugged online blocks. */
+ virtio_mem_for_each_mb_state_rev(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL) {
+ rc = virtio_mem_mb_unplug_any_sb_online(vm, mb_id,
+ &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ mutex_unlock(&vm->hotplug_mutex);
+ cond_resched();
+ mutex_lock(&vm->hotplug_mutex);
+ }
+
+ /* Try to unplug subblocks of plugged online blocks. */
+ virtio_mem_for_each_mb_state_rev(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_ONLINE) {
+ rc = virtio_mem_mb_unplug_any_sb_online(vm, mb_id,
+ &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ mutex_unlock(&vm->hotplug_mutex);
+ cond_resched();
+ mutex_lock(&vm->hotplug_mutex);
+ }
+
+ mutex_unlock(&vm->hotplug_mutex);
+ return nb_sb ? -EBUSY : 0;
+out_unlock:
+ mutex_unlock(&vm->hotplug_mutex);
+ return rc;
+}
+
+/*
+ * 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 mb_id;
+ int rc;
+
+ virtio_mem_for_each_mb_state(vm, mb_id, VIRTIO_MEM_MB_STATE_PLUGGED) {
+ rc = virtio_mem_mb_unplug(vm, mb_id);
+ if (rc)
+ return rc;
+ virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_UNUSED);
+ }
+
+ return 0;
+}
+
+/*
+ * Update all parts of the config that could have changed.
+ */
+static void virtio_mem_refresh_config(struct virtio_mem *vm)
+{
+ const uint64_t phys_limit = 1UL << MAX_PHYSMEM_BITS;
+ 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 = vm->addr + usable_region_size;
+ end_addr = min(end_addr, phys_limit);
+ vm->last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr) - 1;
+
+ /* 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;
+
+ hrtimer_cancel(&vm->retry_timer);
+
+ if (vm->broken)
+ return;
+
+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;
+ }
+}
+
+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(struct virtio_mem *vm)
+{
+ const uint64_t phys_limit = 1UL << MAX_PHYSMEM_BITS;
+ uint16_t node_id;
+
+ if (!vm->vdev->config->get) {
+ dev_err(&vm->vdev->dev, "config access disabled\n");
+ return -EINVAL;
+ }
+
+ /*
+ * We don't want to (un)plug or reuse any memory when in kdump. The
+ * memory is still accessible (but not mapped).
+ */
+ if (is_kdump_kernel()) {
+ dev_warn(&vm->vdev->dev, "disabled in kdump kernel\n");
+ return -EBUSY;
+ }
+
+ /* 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);
+
+ /*
+ * We always hotplug memory in memory block granularity. This way,
+ * we have to wait for exactly one memory block to online.
+ */
+ if (vm->device_block_size > memory_block_size_bytes()) {
+ dev_err(&vm->vdev->dev,
+ "The block size is not supported (too big).\n");
+ return -EINVAL;
+ }
+
+ /* 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 + vm->region_size > phys_limit)
+ dev_warn(&vm->vdev->dev,
+ "Some memory is not addressable. This can make some memory unusable.\n");
+
+ /*
+ * Calculate the subblock size:
+ * - At least MAX_ORDER - 1 / pageblock_order.
+ * - At least the device block size.
+ * In the worst case, a single subblock per memory block.
+ */
+ vm->subblock_size = PAGE_SIZE * 1ul << max_t(uint32_t, MAX_ORDER - 1,
+ pageblock_order);
+ vm->subblock_size = max_t(uint64_t, vm->device_block_size,
+ vm->subblock_size);
+ vm->nb_sb_per_mb = memory_block_size_bytes() / vm->subblock_size;
+
+ /* Round up to the next full memory block */
+ vm->first_mb_id = virtio_mem_phys_to_mb_id(vm->addr - 1 +
+ memory_block_size_bytes());
+ vm->next_mb_id = vm->first_mb_id;
+ vm->last_mb_id = virtio_mem_phys_to_mb_id(vm->addr +
+ vm->region_size) - 1;
+
+ 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);
+ dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
+ memory_block_size_bytes());
+ dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
+ (unsigned long long)vm->subblock_size);
+ if (vm->nid != NUMA_NO_NODE)
+ dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
+
+ return 0;
+}
+
+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;
+
+ vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
+ name, IORESOURCE_SYSTEM_RAM);
+ 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_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;
+
+ /* 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;
+
+ /* create the parent resource for all memory */
+ rc = virtio_mem_create_resource(vm);
+ if (rc)
+ goto out_del_vq;
+
+ /*
+ * 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 = 1;
+ 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_del_resource;
+ rc = register_virtio_mem_device(vm);
+ if (rc)
+ goto out_unreg_mem;
+
+ virtio_device_ready(vdev);
+
+ /* trigger a config update to start processing the requested_size */
+ atomic_set(&vm->config_changed, 1);
+ queue_work(system_freezable_wq, &vm->wq);
+
+ return 0;
+out_unreg_mem:
+ unregister_memory_notifier(&vm->memory_notifier);
+out_del_resource:
+ virtio_mem_delete_resource(vm);
+out_del_vq:
+ vdev->config->del_vqs(vdev);
+out_free_vm:
+ kfree(vm);
+ vdev->priv = NULL;
+
+ return rc;
+}
+
+static void virtio_mem_remove(struct virtio_device *vdev)
+{
+ struct virtio_mem *vm = vdev->priv;
+ 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);
+
+ /*
+ * After we unregistered our callbacks, user space can online partially
+ * plugged offline blocks. Make sure to remove them.
+ */
+ virtio_mem_for_each_mb_state(vm, mb_id,
+ VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) {
+ rc = virtio_mem_mb_remove(vm, mb_id);
+ BUG_ON(rc);
+ virtio_mem_mb_set_state(vm, mb_id, VIRTIO_MEM_MB_STATE_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 (vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] ||
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL] ||
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE] ||
+ vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL]) {
+ dev_warn(&vdev->dev, "device still has system memory added\n");
+ } else {
+ virtio_mem_delete_resource(vm);
+ kfree_const(vm->resource_name);
+ }
+
+ /* remove all tracking data - no locking needed */
+ vfree(vm->mb_state);
+ vfree(vm->sb_bitmap);
+
+ /* reset the device and cleanup the queues */
+ vdev->config->reset(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;
+
+ 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
+};
+
+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");