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

stable inclusion
from stable-v5.10.154
commit bd64a88f364cbe2e19b5f55be1cffef2b47bd0a5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I64YCB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd64a88f364cbe2e19b5f55be1cffef2b47bd0a5

--------------------------------

commit eeb69eab 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: 43d05de2 ("KVM: pass through CPUID(0x80000006)")
Signed-off-by: NJim Mattson <jmattson@google.com>
Message-Id: <20220929225203.2234702-2-jmattson@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLipeng Sang <sanglipeng1@jd.com>

arch/x86/kvm/cpuid.c

@@ -942,7 +942,8 @@ 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] */