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):
1. 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
2. Stop the template VM, set migration x-ignore-shared capability,
migrate "exec:cat>/tmpfs/state", quit it
3. 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
4. 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>
---
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
On 2019/6/14 14:35, Peng Tao 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): > 1. 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 > 2. Stop the template VM, set migration x-ignore-shared capability, > migrate "exec:cat>/tmpfs/state", quit it > 3. 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 > 4. 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 > FYI, corresponding kata pull request is posted at https://github.com/kata-containers/runtime/pull/1799 Cheers, Tao -- Into something rich and strange.
* 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):
> 1. 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
> 2. Stop the template VM, set migration x-ignore-shared capability,
> migrate "exec:cat>/tmpfs/state", quit it
> 3. 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
> 4. 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
* Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
> * 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):
> > 1. 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
> > 2. Stop the template VM, set migration x-ignore-shared capability,
> > migrate "exec:cat>/tmpfs/state", quit it
> > 3. 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
> > 4. 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.
Oh you did :-) That's double fine then!
> 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
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
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