On Mon, Oct 12, 2020 at 02:53:19PM +0200, David Hildenbrand wrote:
>Currently, we do not support device block sizes that exceed the Linux
>memory block size. For example, having a device block size of 1 GiB (e.g.,
>gigantic pages in the hypervisor) won't work with 128 MiB Linux memory
>blocks.
>
>Let's implement Big Block Mode (BBM), whereby we add/remove at least
>one Linux memory block at a time. With a 1 GiB device block size, a Big
>Block (BB) will cover 8 Linux memory blocks.
>
>We'll keep registering the online_page_callback machinery, it will be used
>for safe memory hotunplug in BBM next.
>
>Note: BBM is properly prepared for variable-sized Linux memory
>blocks that we might see in the future. So we won't care how many Linux
>memory blocks a big block actually spans, and how the memory notifier is
>called.
>
>Cc: "Michael S. Tsirkin" <m...@redhat.com>
>Cc: Jason Wang <jasow...@redhat.com>
>Cc: Pankaj Gupta <pankaj.gupta.li...@gmail.com>
>Cc: Michal Hocko <mho...@kernel.org>
>Cc: Oscar Salvador <osalva...@suse.de>
>Cc: Wei Yang <richard.weiy...@linux.alibaba.com>
>Cc: Andrew Morton <a...@linux-foundation.org>
>Signed-off-by: David Hildenbrand <da...@redhat.com>
>---
> drivers/virtio/virtio_mem.c | 484 ++++++++++++++++++++++++++++++------
> 1 file changed, 402 insertions(+), 82 deletions(-)
>
>diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
>index e68d0d99590c..4d396ef98a92 100644
>--- a/drivers/virtio/virtio_mem.c
>+++ b/drivers/virtio/virtio_mem.c
>@@ -30,12 +30,18 @@ MODULE_PARM_DESC(unplug_online, "Try to unplug online
>memory");
> /*
> * virtio-mem currently supports the following modes of operation:
> *
>- * * Sub Block Mode (SBM): A Linux memory block spans 1..X subblocks (SB). The
>+ * * 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
>@@ -61,6 +67,19 @@ enum virtio_mem_sbm_mb_state {
> 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,
>+ VIRTIO_MEM_BBM_BB_COUNT
>+};
>+
> struct virtio_mem {
> struct virtio_device *vdev;
>
>@@ -113,6 +132,9 @@ struct virtio_mem {
> atomic64_t offline_size;
> uint64_t offline_threshold;
>
>+ /* If set, the driver is in SBM, otherwise in BBM. */
>+ bool in_sbm;
>+
> struct {
> /* Id of the first memory block of this device. */
> unsigned long first_mb_id;
>@@ -151,9 +173,27 @@ struct virtio_mem {
> 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 (un)plugged, adding/removing. */
>+ uint64_t bb_size;
>+ } bbm;
>+
> /*
>- * Mutex that protects the sbm.mb_count, sbm.mb_states, and
>- * sbm.sb_states.
>+ * 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
>@@ -247,6 +287,24 @@ 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.
> */
>@@ -259,6 +317,67 @@ static unsigned long virtio_mem_phys_to_sb_id(struct
>virtio_mem *vm,
> 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)
>+
> /*
> * Set the state of a memory block, taking care of the state counter.
> */
>@@ -504,6 +623,17 @@ static int virtio_mem_sbm_add_mb(struct virtio_mem *vm,
>unsigned long mb_id)
> 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.
>@@ -731,20 +861,33 @@ static int virtio_mem_memory_notifier_cb(struct
>notifier_block *nb,
> 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;
>+ unsigned long id;
>
> 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;
>+ 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
>@@ -763,7 +906,8 @@ static int virtio_mem_memory_notifier_cb(struct
>notifier_block *nb,
> break;
> }
> vm->hotplug_active = true;
>- virtio_mem_sbm_notify_going_offline(vm, mb_id);
>+ if (vm->in_sbm)
>+ virtio_mem_sbm_notify_going_offline(vm, id);
> break;
> case MEM_GOING_ONLINE:
> mutex_lock(&vm->hotplug_mutex);
>@@ -773,10 +917,12 @@ static int virtio_mem_memory_notifier_cb(struct
>notifier_block *nb,
> break;
> }
> vm->hotplug_active = true;
>- rc = virtio_mem_sbm_notify_going_online(vm, mb_id);
>+ if (vm->in_sbm)
>+ rc = virtio_mem_sbm_notify_going_online(vm, id);
> break;
> case MEM_OFFLINE:
>- virtio_mem_sbm_notify_offline(vm, mb_id);
>+ if (vm->in_sbm)
>+ virtio_mem_sbm_notify_offline(vm, id);
>
> atomic64_add(size, &vm->offline_size);
> /*
>@@ -790,7 +936,8 @@ static int virtio_mem_memory_notifier_cb(struct
>notifier_block *nb,
> mutex_unlock(&vm->hotplug_mutex);
> break;
> case MEM_ONLINE:
>- virtio_mem_sbm_notify_online(vm, mb_id);
>+ if (vm->in_sbm)
>+ virtio_mem_sbm_notify_online(vm, id);
>
> atomic64_sub(size, &vm->offline_size);
> /*
>@@ -809,7 +956,8 @@ static int virtio_mem_memory_notifier_cb(struct
>notifier_block *nb,
> case MEM_CANCEL_OFFLINE:
> if (!vm->hotplug_active)
> break;
>- virtio_mem_sbm_notify_cancel_offline(vm, mb_id);
>+ if (vm->in_sbm)
>+ virtio_mem_sbm_notify_cancel_offline(vm, id);
> vm->hotplug_active = false;
> mutex_unlock(&vm->hotplug_mutex);
> break;
>@@ -980,27 +1128,29 @@ static void
>virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
> 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);
>+ unsigned long id, sb_id;
> struct virtio_mem *vm;
>- int sb_id;
>+ bool do_online;
>
>- /*
>- * We exploit here that subblocks have at least MAX_ORDER_NR_PAGES.
>- * 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_contains_range(vm, addr, PFN_PHYS(1 << order)))
> 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_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
>+ if (vm->in_sbm) {
>+ /*
>+ * We exploit here that subblocks have at least
>+ * MAX_ORDER_NR_PAGES size/alignment - so we cannot
>+ * cross subblocks within one call.
>+ */
>+ id = virtio_mem_phys_to_mb_id(addr);
>+ sb_id = virtio_mem_phys_to_sb_id(vm, addr);
>+ do_online = virtio_mem_sbm_test_sb_plugged(vm, id,
>+ sb_id, 1);
>+ } else {
>+ do_online = true;
>+ }
>+ if (do_online)
> generic_online_page(page, order);
> else
> virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
>@@ -1180,6 +1330,32 @@ static int virtio_mem_sbm_unplug_sb(struct virtio_mem
>*vm, unsigned long mb_id,
> 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
>@@ -1365,10 +1541,7 @@ static int virtio_mem_sbm_plug_any_sb(struct virtio_mem
>*vm,
> return 0;
> }
>
>-/*
>- * Try to plug the requested amount of memory.
>- */
>-static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
>+static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)
> {
> uint64_t nb_sb = diff / vm->sbm.sb_size;
> unsigned long mb_id;
>@@ -1435,6 +1608,112 @@ static int virtio_mem_plug_request(struct virtio_mem
>*vm, uint64_t diff)
> 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).
>@@ -1573,10 +1852,7 @@ static int virtio_mem_sbm_unplug_any_sb_online(struct
>virtio_mem *vm,
> return 0;
> }
>
>-/*
>- * Try to unplug the requested amount of memory.
>- */
>-static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
>+static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
> {
> uint64_t nb_sb = diff / vm->sbm.sb_size;
> unsigned long mb_id;
>@@ -1642,20 +1918,42 @@ static int virtio_mem_unplug_request(struct virtio_mem
>*vm, uint64_t diff)
> return rc;
> }
>
>+/*
>+ * 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 -EBUSY;
>+}
>+
> /*
> * 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;
>+ unsigned long id;
> int rc;
>
>- virtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_PLUGGED) {
>- rc = virtio_mem_sbm_unplug_mb(vm, mb_id);
>+ 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, mb_id,
>+ virtio_mem_sbm_set_mb_state(vm, id,
> VIRTIO_MEM_SBM_MB_UNUSED);
> }
>
>@@ -1681,7 +1979,13 @@ static void virtio_mem_refresh_config(struct virtio_mem
>*vm)
> usable_region_size, &usable_region_size);
> end_addr = vm->addr + usable_region_size;
> end_addr = min(end_addr, phys_limit);
>- vm->sbm.last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr) - 1;
>+
>+ if (vm->in_sbm)
>+ vm->sbm.last_usable_mb_id =
>+ virtio_mem_phys_to_mb_id(end_addr) - 1;
>+ else
>+ vm->bbm.last_usable_bb_id =
>+ virtio_mem_phys_to_bb_id(vm, end_addr) - 1;
>
> /* see if there is a request to change the size */
> virtio_cread_le(vm->vdev, struct virtio_mem_config, requested_size,
>@@ -1804,6 +2108,7 @@ static int virtio_mem_init_vq(struct virtio_mem *vm)
> static int virtio_mem_init(struct virtio_mem *vm)
> {
> const uint64_t phys_limit = 1UL << MAX_PHYSMEM_BITS;
>+ uint64_t sb_size, addr;
> uint16_t node_id;
>
> if (!vm->vdev->config->get) {
>@@ -1836,16 +2141,6 @@ static int virtio_mem_init(struct virtio_mem *vm)
> if (vm->nid == NUMA_NO_NODE)
> vm->nid = memory_add_physaddr_to_nid(vm->addr);
>
>- /*
>- * 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,
>@@ -1865,20 +2160,35 @@ static int virtio_mem_init(struct virtio_mem *vm)
> * - Is required for now for alloc_contig_range() to work reliably -
> * it doesn't properly handle smaller granularity on ZONE_NORMAL.
> */
>- vm->sbm.sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
>- pageblock_nr_pages) * PAGE_SIZE;
>- vm->sbm.sb_size = max_t(uint64_t, vm->device_block_size,
>- vm->sbm.sb_size);
>- vm->sbm.sbs_per_mb = memory_block_size_bytes() / vm->sbm.sb_size;
>+ sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
>+ pageblock_nr_pages) * PAGE_SIZE;
>+ sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
>+
>+ if (sb_size < memory_block_size_bytes()) {
>+ /* 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 = vm->addr + 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 = vm->device_block_size;
>
>- /* Round up to the next full memory block */
>- vm->sbm.first_mb_id = virtio_mem_phys_to_mb_id(vm->addr - 1 +
>-
>memory_block_size_bytes());
>- vm->sbm.next_mb_id = vm->sbm.first_mb_id;
>+ vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, vm->addr);
Per my understanding, vm->addr is not guaranteed to be bb_size aligned, right?
Why not round up to next big block?
>+ vm->bbm.next_bb_id = vm->bbm.first_bb_id;
>+ }
>
> /* 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);
>+ /* In BBM, we also want at least two big blocks. */
>+ vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size,
>+ vm->offline_threshold);
>
> dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr);
> dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size);
>@@ -1886,8 +2196,12 @@ static int virtio_mem_init(struct virtio_mem *vm)
> (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->sbm.sb_size);
>+ 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);
> if (vm->nid != NUMA_NO_NODE && IS_ENABLED(CONFIG_NUMA))
> dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
>
>@@ -2044,22 +2358,24 @@ static void virtio_mem_remove(struct virtio_device
>*vdev)
> 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_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);
>+ 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.
>+ */
> }
>- /*
>- * 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);
>@@ -2078,8 +2394,12 @@ static void virtio_mem_remove(struct virtio_device
>*vdev)
> }
>
> /* remove all tracking data - no locking needed */
>- vfree(vm->sbm.mb_states);
>- vfree(vm->sbm.sb_states);
>+ if (vm->in_sbm) {
>+ vfree(vm->sbm.mb_states);
>+ vfree(vm->sbm.sb_states);
>+ } else {
>+ vfree(vm->bbm.bb_states);
>+ }
>
> /* reset the device and cleanup the queues */
> vdev->config->reset(vdev);
>--
>2.26.2
--
Wei Yang
Help you, Help me
