[GIT PULL] KVM: x86: Xen change for 6.8

[Sean Christopherson]

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)

----------------------------------------------------------------
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(-)