[PATCH v4 0/5] KVM: x86: Virtualize AMD's "disable CPUID in usermode"

From: Jim Mattson

Date: Wed May 27 2026 - 13:44:28 EST


AMD's "disable CPUID in usermode" feature is analogous to Intel's "CPUID
faulting" feature, but it is advertised and activated differently. The AMD
feature is advertised via CPUID.80000021H:EAX.CpuidUserDis[bit 17] and
activated by setting HWCR.CpuidUserDis[bit 35].

Add virtualization support for the AMD feature.

v3 -> v4:
* Fix typo in commit message for patch 1 [Binbin]
* Fix #GP/CPUID VM-exit precedence in nested VMX [Sashiko]
* Add EXPORT_STATIC_CALL_GPL(kvm_x86_get_cpl)

v1: https://lore.kernel.org/kvm/20260402223108.650572-1-jmattson@xxxxxxxxxx/
v2: https://lore.kernel.org/kvm/20260508170714.489136-1-jmattson@xxxxxxxxxx/
v3: https://lore.kernel.org/kvm/20260513224608.1859737-1-jmattson@xxxxxxxxxx/

Jim Mattson (4):
KVM: x86: Prioritize CPUID faulting over CPUID VM-exits in nested VMX
KVM: x86: Remove supports_cpuid_fault() helper
KVM: x86: Virtualize AMD CPUID faulting
KVM: selftests: Update hwcr_msr_test for CPUID faulting bit

Sean Christopherson (1):
KVM: x86: Consolidate CPUID fault handling for emulator and
interception logic

arch/x86/include/asm/kvm_host.h | 1 -
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kvm/cpuid.c | 7 ++--
arch/x86/kvm/cpuid.h | 14 ++++---
arch/x86/kvm/emulate.c | 6 +--
arch/x86/kvm/kvm_emulate.h | 1 +
arch/x86/kvm/vmx/nested.c | 2 +
arch/x86/kvm/x86.c | 39 ++++++++++---------
.../selftests/kvm/include/x86/processor.h | 1 +
.../testing/selftests/kvm/x86/hwcr_msr_test.c | 9 ++++-
10 files changed, 46 insertions(+), 35 deletions(-)

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2.54.0.794.g4f17f83d09-goog