KVM: x86: Mask off reserved bits in CPUID.80000006H

commit eeb69eab57c6604ac90b3fd8e5ac43f24a5535b1 upstream.

KVM_GET_SUPPORTED_CPUID should only enumerate features that KVM
actually supports. CPUID.80000006H:EDX[17:16] are reserved bits and
should be masked off.

Fixes: 43d05de2bee7 ("KVM: pass through CPUID(0x80000006)")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220929225203.2234702-2-jmattson@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d85a080..7689397 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -906,7 +906,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
                cpuid_entry_override(entry, CPUID_8000_0001_ECX);
                break;
        case 0x80000006:
-               /* L2 cache and TLB: pass through host info. */
+               /* Drop reserved bits, pass host L2 cache and TLB info. */
+               entry->edx &= ~GENMASK(17, 16);
                break;
        case 0x80000007: /* Advanced power management */
                /* invariant TSC is CPUID.80000007H:EDX[8] */