linux-kernel - Re: [GIT PULL] KVM: x86: Xen change for 6.8

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Message-ID: <CABgObfavshc4VZAF0q+EjpXnkA4nVw8NSz_EvNt-iKxoFqgR5w@mail.gmail.com>
Date: Mon, 8 Jan 2024 14:06:06 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] KVM: x86: Xen change for 6.8

On Thu, Jan 4, 2024 at 8:33 PM Sean Christopherson <seanjc@...gle.com> wrote:
>
> A single Xen fix (of sorts) to let userspace workaround buggy guests that don't
> react well to KVM setting the "stable TSC" bit in Xen PV clocks.
>
> The following changes since commit e9e60c82fe391d04db55a91c733df4a017c28b2f:
>
>   selftests/kvm: fix compilation on non-x86_64 platforms (2023-11-21 11:58:25 -0500)
>
> are available in the Git repository at:
>
>   https://github.com/kvm-x86/linux.git tags/kvm-x86-xen-6.8
>
> for you to fetch changes up to 6d72283526090850274d065cd5d60af732cc5fc8:
>
>   KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT (2023-12-07 15:52:57 -0800)

Pulled, thanks.

Paolo



> ----------------------------------------------------------------
> KVM Xen change for 6.8:
>
> To workaround Xen guests that don't expect Xen PV clocks to be marked as being
> based on a stable TSC, add a Xen config knob to allow userspace to opt out of
> KVM setting the "TSC stable" bit in Xen PV clocks.  Note, the "TSC stable" bit
> was added to the PVCLOCK ABI by KVM without an ack from Xen, i.e. KVM isn't
> entirely blameless for the buggy guest behavior.
>
> ----------------------------------------------------------------
> Paul Durrant (1):
>       KVM x86/xen: add an override for PVCLOCK_TSC_STABLE_BIT
>
>  Documentation/virt/kvm/api.rst |  6 ++++++
>  arch/x86/kvm/x86.c             | 28 +++++++++++++++++++++++-----
>  arch/x86/kvm/xen.c             |  9 ++++++++-
>  include/uapi/linux/kvm.h       |  1 +
>  4 files changed, 38 insertions(+), 6 deletions(-)
>