| Message ID | 20220920144024.3559708-1-vkuznets@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i386: Fix KVM_CAP_ADJUST_CLOCK capability check | expand |
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.
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 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)
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 > >
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.
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)
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(-)