[COMMIT master] KVM: ignore AMDs HWCR register access to set the FFDIS bit

[Avi Kivity]

From: Andre Przywara <andre.przyw...@amd.com>

Linux tries to disable the flush filter on all AMD K8 CPUs. Since KVM
does not handle the needed MSR, the injected #GP will panic the Linux
kernel. Ignore setting of the HWCR.FFDIS bit in this MSR to let Linux
boot with an AMD K8 family guest CPU.

Signed-off-by: Andre Przywara <andre.przyw...@amd.com>
Signed-off-by: Avi Kivity <a...@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 9b37043..610bcae 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2139,7 +2139,6 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned 
ecx, u64 data)
                break;
        case MSR_VM_CR:
        case MSR_VM_IGNNE:
-       case MSR_K7_HWCR:
                pr_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, 
data);
                break;
        default:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 82e44f0..ea377f4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -833,6 +833,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 
data)
        case MSR_EFER:
                set_efer(vcpu, data);
                break;
+       case MSR_K7_HWCR:
+               data &= ~(u64)0x40;     /* ignore flush filter disable */
+               if (data != 0) {
+                       pr_unimpl(vcpu, "unimplemented HWCR wrmsr: 0x%llx\n",
+                               data);
+                       return 1;
+               }
+               break;
        case MSR_IA32_DEBUGCTLMSR:
                if (!data) {
                        /* We support the non-activated case already */
--
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