* Peng Tao (tao.peng@linux.alibaba.com) wrote:
By removing the share ram check, qemu is able to migrate to private destination ram when x-ignore-shared capability is on. Then we can create multiple destination VMs based on the same source VM.
This changes the x-ignore-shared migration capability to work similar to Lai's original bypass-shared-memory work(https://lists.gnu.org/archive/html/qemu-devel/2018-04/msg00003.html) which enables kata containers (https://katacontainers.io) to implement the VM templating feature.
An example usage in kata containers(https://katacontainers.io):
- Start the source VM: qemu-system-x86 -m 2G \ -object memory-backend-file,id=mem0,size=2G,share=on,mem-path=/tmpfs/template-memory \ -numa node,memdev=mem0
- Stop the template VM, set migration x-ignore-shared capability, migrate "exec:cat>/tmpfs/state", quit it
- Start target VM: qemu-system-x86 -m 2G \ -object memory-backend-file,id=mem0,size=2G,share=off,mem-path=/tmpfs/template-memory \ -numa node,memdev=mem0 \ -incoming defer
- connect to target VM qmp, set migration x-ignore-shared capability,
migrate_incoming "exec:cat /tmpfs/state" 5. create more target VMs repeating 3 and 4
Cc: Dr. David Alan Gilbert dgilbert@redhat.com Cc: Yury Kotov yury-kotov@yandex-team.ru Cc: Jiangshan Lai laijs@hyper.sh Cc: Xu Wang xu@hyper.sh Signed-off-by: Peng Tao tao.peng@linux.alibaba.com
I think this is OK, but please post this to qemu-devel.
Reviewed-by: Dr. David Alan Gilbert dgilbert@redhat.com
migration/ram.c | 7 ------- 1 file changed, 7 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c index 1ca9ba7..cdb82a3 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -3373,7 +3373,6 @@ static int ram_save_setup(QEMUFile *f, void *opaque) } if (migrate_ignore_shared()) { qemu_put_be64(f, block->mr->addr);
}qemu_put_byte(f, ramblock_is_ignored(block) ? 1 : 0); }
@@ -4340,12 +4339,6 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) } if (migrate_ignore_shared()) { hwaddr addr = qemu_get_be64(f);
bool ignored = qemu_get_byte(f);
if (ignored != ramblock_is_ignored(block)) {
error_report("RAM block %s should %s be migrated",
id, ignored ? "" : "not");
ret = -EINVAL;
} if (ramblock_is_ignored(block) && block->mr->addr != addr) { error_report("Mismatched GPAs for block %s "
-- 1.8.3.1
-- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK