[PATCH] kvm: x86: Add AMD's EX_CFG to the list of ignored MSRs

Eduardo Habkost
2018-12-18T00:34:18Z

Some guests OSes (including Windows 10) write to MSR 0xc001102c
on some cases (possibly while trying to apply a CPU errata).
Make KVM ignore reads and writes to that MSR, so the guest won't
crash.

The MSR is documented as "Execution Unit Configuration (EX_CFG)",
at AMD's "BIOS and Kernel Developer's Guide (BKDG) for AMD Family
15h Models 00h-0Fh Processors".

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kvm/x86.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index c8f73efb4ece..9e39cc8bd989 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -390,6 +390,7 @@
#define MSR_F15H_NB_PERF_CTR 0xc0010241
#define MSR_F15H_PTSC 0xc0010280
#define MSR_F15H_IC_CFG 0xc0011021
+#define MSR_F15H_EX_CFG 0xc001102c

/* Fam 10h MSRs */
#define MSR_FAM10H_MMIO_CONF_BASE 0xc0010058
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9cbce3ec84ec..69f822165fe2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2429,6 +2429,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_AMD64_PATCH_LOADER:
case MSR_AMD64_BU_CFG2:
case MSR_AMD64_DC_CFG:
+ case MSR_F15H_EX_CFG:
break;

case MSR_IA32_UCODE_REV:
@@ -2724,6 +2725,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_AMD64_BU_CFG2:
case MSR_IA32_PERF_CTL:
case MSR_AMD64_DC_CFG:
+ case MSR_F15H_EX_CFG:
msr_info->data = 0;
break;
case MSR_F15H_PERF_CTL0 ... MSR_F15H_PERF_CTR5:
--
2.18.0.rc1.1.g3f1ff2140