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-rw-r--r--arch/x86/kvm/x86.c31
1 files changed, 25 insertions, 6 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4a1ba05f7af3..934b4c6b0bf9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4958,12 +4958,6 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
best = e;
break;
}
- /*
- * Both basic or both extended?
- */
- if (((e->function ^ function) & 0x80000000) == 0)
- if (!best || e->function > best->function)
- best = e;
}
return best;
}
@@ -4983,6 +4977,27 @@ not_found:
return 36;
}
+/*
+ * If no match is found, check whether we exceed the vCPU's limit
+ * and return the content of the highest valid _standard_ leaf instead.
+ * This is to satisfy the CPUID specification.
+ */
+static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
+ u32 function, u32 index)
+{
+ struct kvm_cpuid_entry2 *maxlevel;
+
+ maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
+ if (!maxlevel || maxlevel->eax >= function)
+ return NULL;
+ if (function & 0x80000000) {
+ maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
+ if (!maxlevel)
+ return NULL;
+ }
+ return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
+}
+
void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
{
u32 function, index;
@@ -4995,6 +5010,10 @@ void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
best = kvm_find_cpuid_entry(vcpu, function, index);
+
+ if (!best)
+ best = check_cpuid_limit(vcpu, function, index);
+
if (best) {
kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);