We want to use local migration to update QEMU for running guests.
In this case we don't need to migrate external RAM.
So, add a capability to ignore such blocks during live migration.
Signed-off-by: Yury Kotov <yury-ko...@yandex-team.ru>
---
exec.c | 5 +++++
include/exec/cpu-common.h | 1 +
migration/migration.c | 9 +++++++++
migration/migration.h | 1 +
migration/ram.c | 37 ++++++++++++++++++++++++++++++++++---
qapi/migration.json | 6 +++++-
6 files changed, 55 insertions(+), 4 deletions(-)
diff --git a/exec.c b/exec.c
index ef2f29d7cb..3c3e42993f 100644
--- a/exec.c
+++ b/exec.c
@@ -2000,6 +2000,11 @@ void qemu_ram_unset_migratable(RAMBlock *rb)
rb->flags &= ~RAM_MIGRATABLE;
}
+bool qemu_ram_is_external(RAMBlock *rb)
+{
+ return rb->flags & RAM_EXTERNAL;
+}
+
/* Called with iothread lock held. */
void qemu_ram_set_idstr(RAMBlock *new_block, const char *name, DeviceState
*dev)
{
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 2ad2d6d86b..57e84e5aa4 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -78,6 +78,7 @@ void qemu_ram_set_uf_zeroable(RAMBlock *rb);
bool qemu_ram_is_migratable(RAMBlock *rb);
void qemu_ram_set_migratable(RAMBlock *rb);
void qemu_ram_unset_migratable(RAMBlock *rb);
+bool qemu_ram_is_external(RAMBlock *rb);
size_t qemu_ram_pagesize(RAMBlock *block);
size_t qemu_ram_pagesize_largest(void);
diff --git a/migration/migration.c b/migration/migration.c
index ffc4d9e556..9b789d3535 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1979,6 +1979,15 @@ bool migrate_dirty_bitmaps(void)
return s->enabled_capabilities[MIGRATION_CAPABILITY_DIRTY_BITMAPS];
}
+bool migrate_ignore_external(void)
+{
+ MigrationState *s;
+
+ s = migrate_get_current();
+
+ return s->enabled_capabilities[MIGRATION_CAPABILITY_X_IGNORE_EXTERNAL];
+}
+
bool migrate_use_events(void)
{
MigrationState *s;
diff --git a/migration/migration.h b/migration/migration.h
index e413d4d8b6..06691242f3 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -255,6 +255,7 @@ bool migrate_release_ram(void);
bool migrate_postcopy_ram(void);
bool migrate_zero_blocks(void);
bool migrate_dirty_bitmaps(void);
+bool migrate_ignore_external(void);
bool migrate_auto_converge(void);
bool migrate_use_multifd(void);
diff --git a/migration/ram.c b/migration/ram.c
index 39629254e1..0091a8ae3a 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -166,6 +166,11 @@ out:
#undef RAMBLOCK_FOREACH
+static bool is_ignored_block(RAMBlock *block)
+{
+ return migrate_ignore_external() && qemu_ram_is_external(block);
+}
+
static void ramblock_recv_map_init(void)
{
RAMBlock *rb;
@@ -1537,7 +1542,7 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs,
RAMBlock *rb,
unsigned long *bitmap = rb->bmap;
unsigned long next;
- if (!qemu_ram_is_migratable(rb)) {
+ if (!qemu_ram_is_migratable(rb) || is_ignored_block(rb)) {
return size;
}
@@ -1651,6 +1656,9 @@ static void migration_bitmap_sync(RAMState *rs)
qemu_mutex_lock(&rs->bitmap_mutex);
rcu_read_lock();
RAMBLOCK_FOREACH_MIGRATABLE(block) {
+ if (is_ignored_block(block)) {
+ continue;
+ }
migration_bitmap_sync_range(rs, block, 0, block->used_length);
}
ram_counters.remaining = ram_bytes_remaining();
@@ -2472,19 +2480,27 @@ void acct_update_position(QEMUFile *f, size_t size,
bool zero)
}
}
-uint64_t ram_bytes_total(void)
+static uint64_t ram_bytes_total_common(bool skip_ignored)
{
RAMBlock *block;
uint64_t total = 0;
rcu_read_lock();
RAMBLOCK_FOREACH_MIGRATABLE(block) {
+ if (skip_ignored && is_ignored_block(block)) {
+ continue;
+ }
total += block->used_length;
}
rcu_read_unlock();
return total;
}
+uint64_t ram_bytes_total(void)
+{
+ return ram_bytes_total_common(true);
+}
+
static void xbzrle_load_setup(void)
{
XBZRLE.decoded_buf = g_malloc(TARGET_PAGE_SIZE);
@@ -3162,7 +3178,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
rcu_read_lock();
- qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
+ qemu_put_be64(f, ram_bytes_total_common(false) | RAM_SAVE_FLAG_MEM_SIZE);
RAMBLOCK_FOREACH_MIGRATABLE(block) {
qemu_put_byte(f, strlen(block->idstr));
@@ -3172,6 +3188,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
qemu_put_be64(f, block->page_size);
}
qemu_put_be64(f, block->offset);
+ qemu_put_byte(f, is_ignored_block(block) ? 1 : 0);
}
rcu_read_unlock();
@@ -4135,13 +4152,27 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
}
if (version_id >= 5) {
ram_addr_t offset;
+ bool ignored;
offset = qemu_get_be64(f);
+ ignored = qemu_get_byte(f);
if (block->offset != offset) {
error_report("Mismatched RAM block offset %s "
"%" PRId64 "!= %" PRId64,
id, offset, (uint64_t)block->offset);
ret = -EINVAL;
}
+ if (ignored) {
+ if (!migrate_ignore_external()) {
+ error_report("Unexpected ignored RAM block %s:
"
+ "ignore-external capability is "
+ "disabled", id);
+ ret = -EINVAL;
+ } else if (!qemu_ram_is_external(block)) {
+ error_report("Only external RAM block %s "
+ "can be ignored", id);
+ ret = -EINVAL;
+ }
+ }
}
ram_control_load_hook(f, RAM_CONTROL_BLOCK_REG,
block->idstr);
diff --git a/qapi/migration.json b/qapi/migration.json
index 31b589ec26..10bbac87f8 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -406,13 +406,17 @@
# devices (and thus take locks) immediately at the end of migration.
# (since 3.0)
#
+# @x-ignore-external: If enabled, QEMU will not migrate shared memory
+# (since 4.0)
+#
# Since: 1.2
##
{ 'enum': 'MigrationCapability',
'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
'block', 'return-path', 'pause-before-switchover', 'x-multifd',
- 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate' ] }
+ 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
+ 'x-ignore-external' ] }
##
# @MigrationCapabilityStatus:
--
2.20.1
