linux-kernel - [GIT PULL] KVM: x86: Late CPUID related fix for 6.9

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Date: Mon, 18 Mar 2024 16:16:09 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Sean Christopherson <seanjc@...gle.com>
Subject: [GIT PULL] KVM: x86: Late CPUID related fix for 6.9

Another small series for 6.9.  In hindsight, I could have squeezed this into the
"misc" PR, but since it was from Vitaly, my mind thought "Hyper-V!" and I put in
kvm-x86/hyperv.  *sigh*

FWIW, I'm hoping to eliminate this sort of bug in KVM_SET_CPUID{2,} by swapping
the incoming CPUID with the current CPUID, and undoing the swap on failure,  But
that's firmly a future cleanup (if it even works).

The following changes since commit 41bccc98fb7931d63d03f326a746ac4d429c1dd3:

  Linux 6.8-rc2 (2024-01-28 17:01:12 -0800)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-pvunhalt-6.9

for you to fetch changes up to c2585047c8e185b070ad5c7bd887ef59cee3941f:

  KVM: selftests: Check that PV_UNHALT is cleared when HLT exiting is disabled (2024-03-06 09:59:20 -0800)

----------------------------------------------------------------
Fix a bug in KVM_SET_CPUID{2,} where KVM looks at the wrong CPUID entries (old
vs. new) and ultimately neglects to clear PV_UNHALT from vCPUs with HLT-exiting
disabled.

----------------------------------------------------------------
Vitaly Kuznetsov (3):
      KVM: x86: Introduce __kvm_get_hypervisor_cpuid() helper
      KVM: x86: Use actual kvm_cpuid.base for clearing KVM_FEATURE_PV_UNHALT
      KVM: selftests: Check that PV_UNHALT is cleared when HLT exiting is disabled

 arch/x86/kvm/cpuid.c                               | 44 +++++++++++++---------
 .../selftests/kvm/include/x86_64/processor.h       |  9 +++++
 tools/testing/selftests/kvm/x86_64/kvm_pv_test.c   | 39 +++++++++++++++++++
 3 files changed, 75 insertions(+), 17 deletions(-)