[PATCH 0/2] KVM: VMX: Fix and test for emulation + exception

From: Sean Christopherson
Date: Tue Dec 28 2021 - 18:24:49 EST


Fix an issue that allows userspace to trigger a WARN by rejecting KVM_RUN
if userspace attempts to run a vCPU that require emulation in KVM and has
a pending exception, which is not supported in KVM.

No small part of me thinks this is a waste of code and that we'd be better
off just deleting the WARN. But it's also not hard to fix and there are
still folks out there that run on Core2...

Intentionally didn't tag for stable. I highly doubt this actually fixes
anything for anyone, the goal is purely to prevent userspace from triggering
the WARN.

Sean Christopherson (2):
KVM: VMX: Reject KVM_RUN if emulation is required with pending
exception
KVM: selftests: Add a test to force emulation with a pending exception

arch/x86/include/asm/kvm-x86-ops.h | 1 +
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm/svm.c | 6 +
arch/x86/kvm/vmx/vmx.c | 22 ++-
arch/x86/kvm/x86.c | 12 +-
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../vmx_exception_with_invalid_guest_state.c | 139 ++++++++++++++++++
8 files changed, 178 insertions(+), 5 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_exception_with_invalid_guest_state.c

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2.34.1.448.ga2b2bfdf31-goog