KVM: x86: Add helpers to perform CPUID-based guest vendor check

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Add helpers to provide CPUID-based guest vendor checks, i.e. to do the
ugly register comparisons.  Use the new helpers to check for an AMD
guest vendor in guest_cpuid_is_amd() as well as in the existing emulator
flows.

Using the new helpers fixes a _very_ theoretical bug where
guest_cpuid_is_amd() would get a false positive on a non-AMD virtual CPU
with a vendor string beginning with "Auth" due to the previous logic
only checking EBX.  It also fixes a marginally less theoretically bug
where guest_cpuid_is_amd() would incorrectly return false for a guest
CPU with "AMDisbetter!" as its vendor string.

Fixes: a0c0feb579 ("KVM: x86: reserve bit 8 of non-leaf PDPEs and PML4Es in 64-bit mode on AMD")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2020-03-04 17:34:32 -08:00 • committed by Paolo Bonzini

parent b7fb8488c8

commit 15608ed03f

3 changed files with 33 additions and 29 deletions

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2

arch/x86/kvm/cpuid.h

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36

arch/x86/kvm/emulate.c

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24

arch/x86/kvm/kvm_emulate.h

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