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

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Date:   Tue, 28 Dec 2021 23:24:35 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+82112403ace4cbd780d8@...kaller.appspotmail.com
Subject: [PATCH 0/2] KVM: VMX: Fix and test for emulation + exception

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

-- 
2.34.1.448.ga2b2bfdf31-goog