On 9/26/2019 8:04 AM, Jim Mattson wrote:
When the guest CPUID information represents an AMD vCPU, return all
zeroes for queries of undefined CPUID leaves, whether or not they are
in range.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Fixes: bd22f5cfcfe8f6 ("KVM: move and fix substitue search for missing CPUID entries")
Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
Reviewed-by: Jacob Xu <jacobhxu@xxxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 35e2f930a4b79..0377d2820a7aa 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -988,9 +988,11 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
/*
* Intel CPUID semantics treats any query for an out-of-range
* leaf as if the highest basic leaf (i.e. CPUID.0H:EAX) were
- * requested.
+ * requested. AMD CPUID semantics returns all zeroes for any
+ * undefined leaf, whether or not the leaf is in range.
*/
- if (!entry && check_limit && !cpuid_function_in_range(vcpu, function)) {
+ if (!entry && check_limit && !guest_cpuid_is_amd(vcpu) &&
+ !cpuid_function_in_range(vcpu, function)) {
IIUC, the parameter check_limit is to indicate whether return highest
basic leaf when out-of-range. Here you just makes check_limit meaningless.
Maybe we can do like this to use check_limit reasonably：
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0377d2820a7a..e6a61f3f6c0c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1035,7 +1035,8 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
eax = kvm_rax_read(vcpu);
ecx = kvm_rcx_read(vcpu);
- kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, true);
+ kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx,
+ guest_cpuid_is_amd(vcpu) ? false: true);
kvm_rax_write(vcpu, eax);
kvm_rbx_write(vcpu, ebx);
kvm_rcx_write(vcpu, ecx);
max = kvm_find_cpuid_entry(vcpu, 0, 0);
if (max) {
function = max->eax;
