KVM: x86: disable MPX if host did not enable MPX XSAVE features

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When eager FPU is disabled, KVM will still see the MPX bit in CPUID and
presumably the MPX vmentry and vmexit controls.  However, it will not
be able to expose the MPX XSAVE features to the guest, because the guest's
accessible XSAVE features are always a subset of host_xcr0.

In this case, we should disable the MPX CPUID bit, the BNDCFGS MSR,
and the MPX vmentry and vmexit controls for nested virtualization.
It is then unnecessary to enable guest eager FPU if the guest has the
MPX CPUID bit set.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Paolo Bonzini 2016-03-08 09:52:13 +01:00

parent ab92f30875

commit a87036add0

3 changed files with 17 additions and 18 deletions

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13

arch/x86/kvm/cpuid.c

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9

arch/x86/kvm/cpuid.h

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13

arch/x86/kvm/vmx.c

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