KVM: x86: Calculate the supported xcr0 mask at load time

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Add a new global variable, supported_xcr0, to track which xcr0 bits can
be exposed to the guest instead of calculating the mask on every call.
The supported bits are constant for a given instance of KVM.

This paves the way toward eliminating the ->mpx_supported() call in
kvm_mpx_supported(), e.g. eliminates multiple retpolines in VMX's nested
VM-Enter path, and eventually toward eliminating ->mpx_supported()
altogether.

No functional change intended.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Sean Christopherson 2020-03-02 15:56:23 -08:00 • committed by Paolo Bonzini

parent 2ef7619d43

commit cfc481810c

5 changed files with 27 additions and 32 deletions

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32

arch/x86/kvm/cpuid.c

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2

arch/x86/kvm/svm.c

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4

arch/x86/kvm/vmx/vmx.c

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14

arch/x86/kvm/x86.c

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arch/x86/kvm/x86.h

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