From 006366b96c16090c9b73e8930b8dba0251658d83 Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@google.com>
Date: Thu, 29 Sep 2022 15:52:00 -0700
Subject: [PATCH] KVM: x86: Mask off reserved bits in CPUID.80000008H
commit 7030d8530e533844e2f4b0e7476498afcd324634 upstream.
KVM_GET_SUPPORTED_CPUID should only enumerate features that KVM
actually supports. The following ranges of CPUID.80000008H are reserved
and should be masked off:
ECX[31:18]
ECX[11:8]
In addition, the PerfTscSize field at ECX[17:16] should also be zero
because KVM does not set the PERFTSC bit at CPUID.80000001H.ECX[27].
Fixes: 24c82e576b78 ("KVM: Sanitize cpuid")
Signed-off-by: Jim Mattson <jmattson@google.com>
Message-Id: <20220929225203.2234702-3-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>
---
arch/x86/kvm/cpuid.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 6ca34db82d86..478721a33a1f 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -937,6 +937,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
g_phys_as = phys_as;
entry->eax = g_phys_as | (virt_as << 8);
+ entry->ecx &= ~(GENMASK(31, 16) | GENMASK(11, 8));
entry->edx = 0;
cpuid_entry_override(entry, CPUID_8000_0008_EBX);
break;