KVM: x86: Mask off reserved bits in CPUID.8000001AH

BugLink: https://bugs.launchpad.net/bugs/1998843
commit 079f6889818dd07903fb36c252532ab47ebb6d48 upstream.

KVM_GET_SUPPORTED_CPUID should only enumerate features that KVM
actually supports. In the case of CPUID.8000001AH, only three bits are
currently defined. The 125 reserved bits should be masked off.

Fixes: 24c82e576b78 ("KVM: Sanitize cpuid")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220929225203.2234702-4-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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 76893975b116a70aa682b8ee2d6eb15cb0be8f1a..6ca34db82d86c88b480d999fb5d9127d909675b1 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -956,6 +956,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
                entry->ecx = entry->edx = 0;
                break;
        case 0x8000001a:
+               entry->eax &= GENMASK(2, 0);
+               entry->ebx = entry->ecx = entry->edx = 0;
+               break;
        case 0x8000001e:
                break;
        case 0x8000001F: