* [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
@ 2022-09-20 14:40 Vitaly Kuznetsov
2022-09-20 18:33 ` Marcelo Tosatti
2022-09-27 9:45 ` Vitaly Kuznetsov
0 siblings, 2 replies; 6+ messages in thread
From: Vitaly Kuznetsov @ 2022-09-20 14:40 UTC (permalink / raw)
To: qemu-devel, Paolo Bonzini; +Cc: Marcelo Tosatti, Oliver Upton, Maxim Levitsky
KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values in
KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2
guest reboots immediately after migration. KVM, however, is not to
blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the
result is all supported flags (which the above mentioned KVM commit
enhanced) but kvm_has_adjust_clock_stable() wants it to be
KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable'
is not set in vmstate and the saved clock reading is discarded in
kvmclock_vm_state_change().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
target/i386/kvm/kvm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index a1fd1f53791d..c33192a87dcb 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void)
{
int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
- return (ret == KVM_CLOCK_TSC_STABLE);
+ return ret & KVM_CLOCK_TSC_STABLE;
}
bool kvm_has_adjust_clock(void)
--
2.37.3
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
2022-09-20 14:40 [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check Vitaly Kuznetsov
@ 2022-09-20 18:33 ` Marcelo Tosatti
2022-09-27 9:45 ` Vitaly Kuznetsov
1 sibling, 0 replies; 6+ messages in thread
From: Marcelo Tosatti @ 2022-09-20 18:33 UTC (permalink / raw)
To: Vitaly Kuznetsov; +Cc: qemu-devel, Paolo Bonzini, Oliver Upton, Maxim Levitsky
On Tue, Sep 20, 2022 at 04:40:24PM +0200, Vitaly Kuznetsov wrote:
> KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values in
> KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2
> guest reboots immediately after migration. KVM, however, is not to
> blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the
> result is all supported flags (which the above mentioned KVM commit
> enhanced) but kvm_has_adjust_clock_stable() wants it to be
> KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable'
> is not set in vmstate and the saved clock reading is discarded in
> kvmclock_vm_state_change().
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> target/i386/kvm/kvm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index a1fd1f53791d..c33192a87dcb 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void)
> {
> int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
>
> - return (ret == KVM_CLOCK_TSC_STABLE);
> + return ret & KVM_CLOCK_TSC_STABLE;
> }
>
> bool kvm_has_adjust_clock(void)
> --
> 2.37.3
>
>
ACK.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
2022-09-20 14:40 [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check Vitaly Kuznetsov
2022-09-20 18:33 ` Marcelo Tosatti
@ 2022-09-27 9:45 ` Vitaly Kuznetsov
2022-10-07 9:26 ` Vitaly Kuznetsov
1 sibling, 1 reply; 6+ messages in thread
From: Vitaly Kuznetsov @ 2022-09-27 9:45 UTC (permalink / raw)
To: qemu-devel, Paolo Bonzini; +Cc: Marcelo Tosatti, Oliver Upton, Maxim Levitsky
Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values in
> KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2
> guest reboots immediately after migration. KVM, however, is not to
> blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the
> result is all supported flags (which the above mentioned KVM commit
> enhanced) but kvm_has_adjust_clock_stable() wants it to be
> KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable'
> is not set in vmstate and the saved clock reading is discarded in
> kvmclock_vm_state_change().
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> target/i386/kvm/kvm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index a1fd1f53791d..c33192a87dcb 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void)
> {
> int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
>
> - return (ret == KVM_CLOCK_TSC_STABLE);
> + return ret & KVM_CLOCK_TSC_STABLE;
> }
>
> bool kvm_has_adjust_clock(void)
Ping) This issue seems to introduce major migration issues with KVM >= v5.16
--
Vitaly
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
2022-09-27 9:45 ` Vitaly Kuznetsov
@ 2022-10-07 9:26 ` Vitaly Kuznetsov
2022-10-07 10:49 ` Paolo Bonzini
0 siblings, 1 reply; 6+ messages in thread
From: Vitaly Kuznetsov @ 2022-10-07 9:26 UTC (permalink / raw)
To: qemu-devel, Paolo Bonzini; +Cc: Marcelo Tosatti, Oliver Upton, Maxim Levitsky
Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> Vitaly Kuznetsov <vkuznets@redhat.com> writes:
>
>> KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values in
>> KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2
>> guest reboots immediately after migration. KVM, however, is not to
>> blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the
>> result is all supported flags (which the above mentioned KVM commit
>> enhanced) but kvm_has_adjust_clock_stable() wants it to be
>> KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable'
>> is not set in vmstate and the saved clock reading is discarded in
>> kvmclock_vm_state_change().
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>> target/i386/kvm/kvm.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
>> index a1fd1f53791d..c33192a87dcb 100644
>> --- a/target/i386/kvm/kvm.c
>> +++ b/target/i386/kvm/kvm.c
>> @@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void)
>> {
>> int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
>>
>> - return (ret == KVM_CLOCK_TSC_STABLE);
>> + return ret & KVM_CLOCK_TSC_STABLE;
>> }
>>
>> bool kvm_has_adjust_clock(void)
>
> Ping) This issue seems to introduce major migration issues with KVM >= v5.16
Ping)
--
Vitaly
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
2022-10-07 9:26 ` Vitaly Kuznetsov
@ 2022-10-07 10:49 ` Paolo Bonzini
2022-10-07 11:53 ` Vitaly Kuznetsov
0 siblings, 1 reply; 6+ messages in thread
From: Paolo Bonzini @ 2022-10-07 10:49 UTC (permalink / raw)
To: Vitaly Kuznetsov
Cc: qemu-devel, Marcelo Tosatti, Oliver Upton, Maxim Levitsky
[-- Attachment #1: Type: text/plain, Size: 1597 bytes --]
Hi, a similar patch is now in.
Paolo
Il ven 7 ott 2022, 05:26 Vitaly Kuznetsov <vkuznets@redhat.com> ha scritto:
> Vitaly Kuznetsov <vkuznets@redhat.com> writes:
>
> > Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> >
> >> KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values
> in
> >> KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2
> >> guest reboots immediately after migration. KVM, however, is not to
> >> blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the
> >> result is all supported flags (which the above mentioned KVM commit
> >> enhanced) but kvm_has_adjust_clock_stable() wants it to be
> >> KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable'
> >> is not set in vmstate and the saved clock reading is discarded in
> >> kvmclock_vm_state_change().
> >>
> >> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> >> ---
> >> target/i386/kvm/kvm.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> >> index a1fd1f53791d..c33192a87dcb 100644
> >> --- a/target/i386/kvm/kvm.c
> >> +++ b/target/i386/kvm/kvm.c
> >> @@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void)
> >> {
> >> int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
> >>
> >> - return (ret == KVM_CLOCK_TSC_STABLE);
> >> + return ret & KVM_CLOCK_TSC_STABLE;
> >> }
> >>
> >> bool kvm_has_adjust_clock(void)
> >
> > Ping) This issue seems to introduce major migration issues with KVM >=
> v5.16
>
> Ping)
>
> --
> Vitaly
>
>
[-- Attachment #2: Type: text/html, Size: 2486 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check
2022-10-07 10:49 ` Paolo Bonzini
@ 2022-10-07 11:53 ` Vitaly Kuznetsov
0 siblings, 0 replies; 6+ messages in thread
From: Vitaly Kuznetsov @ 2022-10-07 11:53 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: qemu-devel, Marcelo Tosatti, Oliver Upton, Maxim Levitsky
Paolo Bonzini <pbonzini@redhat.com> writes:
> Hi, a similar patch is now in.
>
Indeed,
commit c4ef867f2949bf2a2ae18a4e27cf1a34bbc8aecb
Author: Ray Zhang <zhanglei002@gmail.com>
Date: Thu Sep 22 18:05:23 2022 +0800
target/i386/kvm: fix kvmclock_current_nsec: Assertion `time.tsc_timestamp <= migration_tsc' failed
solves the problem as well.
--
Vitaly
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-10-07 13:33 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-09-20 14:40 [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check Vitaly Kuznetsov
2022-09-20 18:33 ` Marcelo Tosatti
2022-09-27 9:45 ` Vitaly Kuznetsov
2022-10-07 9:26 ` Vitaly Kuznetsov
2022-10-07 10:49 ` Paolo Bonzini
2022-10-07 11:53 ` Vitaly Kuznetsov
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).