From: David Woodhouse <dwmw2@infradead.org>
To: paul@xen.org, Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+352e553a86e0d75f5120@syzkaller.appspotmail.com,
Paul Durrant <pdurrant@amazon.com>
Subject: Re: [PATCH 09/10] KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock update)
Date: Tue, 21 Jan 2025 09:16:29 -0800 [thread overview]
Message-ID: <a71d0215ebc34e132081e856f116ca5fcbda41b4.camel@infradead.org> (raw)
In-Reply-To: <eb45ff29-f551-483e-9930-1fa545fb83aa@xen.org>
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On Tue, 2025-01-21 at 15:59 +0000, Paul Durrant wrote:
> On 21/01/2025 15:44, Sean Christopherson wrote:
> [snip]
> >
> > I think it's ok to keep the Hyper-V TSC page in this case. It's not that the Xen
> > PV clock is truly unstable, it's that some guests get tripped up by the STABLE
> > flag. A guest that can't handle the STABLE flag has bigger problems than the
> > existence of a completely unrelated clock that is implied to be stable.
> >
>
> Agreed.
>
> > > I don't know if anyone combines Xen and Hyper-V emulation capabilities for
> > > the same guest on KVM though.)
> >
> > That someone would have to be quite "brave" :-D
>
> Maybe :-)
Xen itself does offer some Hyper-V enlightenments, and we might
reasonably expect KVM-based hypervisors to offer the same. We
explicitly do account for the KVM CPUID leaves moving up to let the
Hyper-V ones exist.
I don't recall if Xen's Hyper-V support includes the TSC page though.
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next prev parent reply other threads:[~2025-01-21 17:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-18 0:55 [PATCH 00/10] KVM: x86: pvclock fixes and cleanups Sean Christopherson
2025-01-18 0:55 ` [PATCH 01/10] KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend notifier Sean Christopherson
2025-01-21 16:01 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 02/10] KVM: x86: Eliminate "handling" of impossible errors during SUSPEND Sean Christopherson
2025-01-21 16:03 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 03/10] KVM: x86: Drop local pvclock_flags variable in kvm_guest_time_update() Sean Christopherson
2025-01-21 16:05 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 04/10] KVM: x86: Set PVCLOCK_GUEST_STOPPED only for kvmclock, not for Xen PV clock Sean Christopherson
2025-01-21 16:42 ` Paul Durrant
2025-01-21 17:09 ` Sean Christopherson
2025-01-21 17:15 ` Paul Durrant
2025-01-21 18:32 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 05/10] KVM: x86: Don't bleed PVCLOCK_GUEST_STOPPED across PV clocks Sean Christopherson
2025-01-21 16:54 ` Paul Durrant
2025-01-21 17:11 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 06/10] KVM: x86/xen: Use guest's copy of pvclock when starting timer Sean Christopherson
2025-01-21 16:58 ` Paul Durrant
2025-01-21 18:45 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 07/10] KVM: x86: Pass reference pvclock as a param to kvm_setup_guest_pvclock() Sean Christopherson
2025-01-21 17:00 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 08/10] KVM: x86: Remove per-vCPU "cache" of its reference pvclock Sean Christopherson
2025-01-21 17:03 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 09/10] KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock update) Sean Christopherson
2025-01-20 14:49 ` Vitaly Kuznetsov
2025-01-21 15:44 ` Sean Christopherson
2025-01-21 15:59 ` Paul Durrant
2025-01-21 17:16 ` David Woodhouse [this message]
2025-01-21 17:30 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 10/10] KVM: x86: Override TSC_STABLE flag for Xen PV clocks in kvm_guest_time_update() Sean Christopherson
2025-01-21 17:05 ` Paul Durrant
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