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" <mst@redhat.com>
Cc: Jason Wang <redacted>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <redacted>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <redacted>
---
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);