* [Bug 53851] New: nVMX: Support live migration of whole L1 guest
@ 2013-02-14 14:36 bugzilla-daemon
2013-02-14 14:37 ` [Bug 53851] " bugzilla-daemon
` (5 more replies)
0 siblings, 6 replies; 8+ messages in thread
From: bugzilla-daemon @ 2013-02-14 14:36 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
Summary: nVMX: Support live migration of whole L1 guest
Product: Virtualization
Version: unspecified
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: kvm
AssignedTo: virtualization_kvm@kernel-bugs.osdl.org
ReportedBy: nyh@math.technion.ac.il
Regression: No
We need to support live migration of a guest, even if it is running a
hypervisor with sub-guests.
I.e., this issue is about supporting live migration of a whole L1 guest
hypervisor, together with its L2 guests.
One option is to add ioctls for saving and restoring a currently-running L2
guest's state (vmcs01, vcpu_vmx.nested, and perhaps more things?).
A different option is to force an exit from L2 to L1 during live migration. We
can use a spurious external interrupt exit (hoping L1 will ignore it and
immediately return to L2), or hide this exit from L1 - add ioctl for L2->L1
exit (if in L2) and another ioctl for reentry used on the receiving hypervisor
(it will need to know to run it - i.e., is_guest_mode(vcpu) also needs to be
migrated). Note how the exit from L2 to L1 includes writing all the L2's state
from host memory (vmcs02) to guest memory (vmcs12), where it will be migrated
together with the rest of the guest.
See discussion in http://www.mail-archive.com/kvm@vger.kernel.org/msg54257.html
on comparing these two options, and how one approach should be chosen for both
nVMX and nSVM.
Note that additionally, we need to also save/restore vmx->nested.vmxon (whether
the migrated L1 guest ever did VMXON), and also vmx->nested.current_vmptr (last
VMPTRLDed VMCS).
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* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
@ 2013-02-14 14:37 ` bugzilla-daemon
2013-02-26 15:27 ` bugzilla-daemon
` (4 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: bugzilla-daemon @ 2013-02-14 14:37 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
Nadav Har'El <nyh@math.technion.ac.il> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |53601
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* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
2013-02-14 14:37 ` [Bug 53851] " bugzilla-daemon
@ 2013-02-26 15:27 ` bugzilla-daemon
2015-03-17 3:53 ` bugzilla-daemon
` (3 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: bugzilla-daemon @ 2013-02-26 15:27 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
--- Comment #1 from Nadav Har'El <nyh@math.technion.ac.il> 2013-02-26 15:27:02 ---
Another issue to consider for live migration: right now we only kunmap() and
release_page_dirty() the vmcs12 page after a vmclear (or vmxof, etc.). However,
we may need to do this also on exit to user space (KVM_VCPU_RUN ioctl
completes), so that live migration knows this page is dirty and needs to be
copied.
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* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
2013-02-14 14:37 ` [Bug 53851] " bugzilla-daemon
2013-02-26 15:27 ` bugzilla-daemon
@ 2015-03-17 3:53 ` bugzilla-daemon
2018-02-15 9:44 ` bugzilla-daemon
` (2 subsequent siblings)
5 siblings, 0 replies; 8+ messages in thread
From: bugzilla-daemon @ 2015-03-17 3:53 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
Bandan Das <bsd@makefile.in> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |94971
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* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
` (2 preceding siblings ...)
2015-03-17 3:53 ` bugzilla-daemon
@ 2018-02-15 9:44 ` bugzilla-daemon
2021-06-09 8:55 ` bugzilla-daemon
2021-06-09 9:15 ` bugzilla-daemon
5 siblings, 0 replies; 8+ messages in thread
From: bugzilla-daemon @ 2018-02-15 9:44 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
Dennis (dennis@transip.nl) changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |198621
Referenced Bugs:
https://bugzilla.kernel.org/show_bug.cgi?id=198621
[Bug 198621] KVM Guest panics when running own guest, while being live migrated
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* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
` (3 preceding siblings ...)
2018-02-15 9:44 ` bugzilla-daemon
@ 2021-06-09 8:55 ` bugzilla-daemon
2021-06-09 9:14 ` Maxim Levitsky
2021-06-09 9:15 ` bugzilla-daemon
5 siblings, 1 reply; 8+ messages in thread
From: bugzilla-daemon @ 2021-06-09 8:55 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
--- Comment #2 from christian.rohmann@frittentheke.de ---
Sorry for replying to this rather old bug - I was pointed to this via
https://www.linux-kvm.org/page/Nested_Guests#Limitations
If I may ask, is this really the last state of discussion and work on this
issue?
Looking at i.e.
* https://github.com/qemu/qemu/commit/ebbfef2f34cfc749c045a4569dedb4f748ec024a
*
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=039aeb9deb9291f3b19c375a8bc6fa7f768996cc
there have been commits for the kernel as well as QEMU to support migration of
nested VMs.
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* Re: [Bug 53851] nVMX: Support live migration of whole L1 guest
2021-06-09 8:55 ` bugzilla-daemon
@ 2021-06-09 9:14 ` Maxim Levitsky
0 siblings, 0 replies; 8+ messages in thread
From: Maxim Levitsky @ 2021-06-09 9:14 UTC (permalink / raw)
To: bugzilla-daemon, kvm
On Wed, 2021-06-09 at 08:55 +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=53851
>
> --- Comment #2 from christian.rohmann@frittentheke.de ---
> Sorry for replying to this rather old bug - I was pointed to this via
> https://www.linux-kvm.org/page/Nested_Guests#Limitations
>
>
> If I may ask, is this really the last state of discussion and work on this
> issue?
> Looking at i.e.
>
> * https://github.com/qemu/qemu/commit/ebbfef2f34cfc749c045a4569dedb4f748ec024a
> *
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=039aeb9deb9291f3b19c375a8bc6fa7f768996cc
>
>
> there have been commits for the kernel as well as QEMU to support migration of
> nested VMs.
>
AFAIK, running nested guests and migration while nested guest is running should
work on both Intel and AMD, but there were lots of fixes in this area recently
so a very new kernel should be used.
Plus in some cases if the nested guest is 32 bit, the migration still can fail,
on Intel at least, last time I checked. On AMD I just recently fixed
such issue for 32 bit guest and it seems to work for me.
I also know that if the nested guest is hyper-v enabled (which is a bit overkill as
this brings us to a double nesting), then it crashes once in a whileafter lots of migration
cycles.
So there are still bugs, but overall it works.
Best regards,
Maxim Levitsky
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug 53851] nVMX: Support live migration of whole L1 guest
2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
` (4 preceding siblings ...)
2021-06-09 8:55 ` bugzilla-daemon
@ 2021-06-09 9:15 ` bugzilla-daemon
5 siblings, 0 replies; 8+ messages in thread
From: bugzilla-daemon @ 2021-06-09 9:15 UTC (permalink / raw)
To: kvm
https://bugzilla.kernel.org/show_bug.cgi?id=53851
--- Comment #3 from mlevitsk@redhat.com ---
On Wed, 2021-06-09 at 08:55 +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> https://bugzilla.kernel.org/show_bug.cgi?id=53851
>
> --- Comment #2 from christian.rohmann@frittentheke.de ---
> Sorry for replying to this rather old bug - I was pointed to this via
> https://www.linux-kvm.org/page/Nested_Guests#Limitations
>
>
> If I may ask, is this really the last state of discussion and work on this
> issue?
> Looking at i.e.
>
> *
> https://github.com/qemu/qemu/commit/ebbfef2f34cfc749c045a4569dedb4f748ec024a
> *
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=039aeb9deb9291f3b19c375a8bc6fa7f768996cc
>
>
> there have been commits for the kernel as well as QEMU to support migration
> of
> nested VMs.
>
AFAIK, running nested guests and migration while nested guest is running should
work on both Intel and AMD, but there were lots of fixes in this area recently
so a very new kernel should be used.
Plus in some cases if the nested guest is 32 bit, the migration still can fail,
on Intel at least, last time I checked. On AMD I just recently fixed
such issue for 32 bit guest and it seems to work for me.
I also know that if the nested guest is hyper-v enabled (which is a bit
overkill as
this brings us to a double nesting), then it crashes once in a whileafter lots
of migration
cycles.
So there are still bugs, but overall it works.
Best regards,
Maxim Levitsky
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2013-02-14 14:36 [Bug 53851] New: nVMX: Support live migration of whole L1 guest bugzilla-daemon
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2013-02-26 15:27 ` bugzilla-daemon
2015-03-17 3:53 ` bugzilla-daemon
2018-02-15 9:44 ` bugzilla-daemon
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