KVM: x86: avoid incorrect writes to host MSR_IA32_SPEC_CTRL

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If the guest is configured to have SPEC_CTRL but the host does not
(which is a nonsensical configuration but these are not explicitly
forbidden) then a host-initiated MSR write can write vmx->spec_ctrl
(respectively svm->spec_ctrl) and trigger a #GP when KVM tries to
restore the host value of the MSR.  Add a more comprehensive check
for valid bits of SPEC_CTRL, covering host CPUID flags and,
since we are at it and it is more correct that way, guest CPUID
flags too.

For AMD, remove the unnecessary is_guest_mode check around setting
the MSR interception bitmap, so that the code looks the same as
for Intel.

Cc: Jim Mattson <jmattson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Paolo Bonzini 2020-01-20 16:33:06 +01:00

parent 4425f567b0

commit 6441fa6178

4 changed files with 29 additions and 10 deletions

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9

arch/x86/kvm/svm.c

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7

arch/x86/kvm/vmx/vmx.c

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22

arch/x86/kvm/x86.c

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1

arch/x86/kvm/x86.h

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