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-rw-r--r--arch/x86/include/asm/msr-index.h1
-rw-r--r--arch/x86/kvm/x86.c19
2 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 823d48223400..fd5a1f365c95 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -43,6 +43,7 @@
#define MSR_MTRRcap 0x000000fe
#define MSR_IA32_BBL_CR_CTL 0x00000119
+#define MSR_IA32_BBL_CR_CTL3 0x0000011e
#define MSR_IA32_SYSENTER_CS 0x00000174
#define MSR_IA32_SYSENTER_ESP 0x00000175
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a7f65aa6eef6..7faf262ab202 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1592,6 +1592,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
} else
return set_msr_hyperv(vcpu, msr, data);
break;
+ case MSR_IA32_BBL_CR_CTL3:
+ /* Drop writes to this legacy MSR -- see rdmsr
+ * counterpart for further detail.
+ */
+ pr_unimpl(vcpu, "ignored wrmsr: 0x%x data %llx\n", msr, data);
+ break;
default:
if (msr && (msr == vcpu->kvm->arch.xen_hvm_config.msr))
return xen_hvm_config(vcpu, data);
@@ -1846,6 +1852,19 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
} else
return get_msr_hyperv(vcpu, msr, pdata);
break;
+ case MSR_IA32_BBL_CR_CTL3:
+ /* This legacy MSR exists but isn't fully documented in current
+ * silicon. It is however accessed by winxp in very narrow
+ * scenarios where it sets bit #19, itself documented as
+ * a "reserved" bit. Best effort attempt to source coherent
+ * read data here should the balance of the register be
+ * interpreted by the guest:
+ *
+ * L2 cache control register 3: 64GB range, 256KB size,
+ * enabled, latency 0x1, configured
+ */
+ data = 0xbe702111;
+ break;
default:
if (!ignore_msrs) {
pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);