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

[Denis Plotnikov]

From: Eduardo Habkost <ehabkost at redhat.com>

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".

Cc: stable at vger.kernel.org
Signed-off-by: Eduardo Habkost <ehabkost at redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>

https://jira.sw.ru/browse/PSBM-95434

Cherry-picked-by: Denis Plotnikov <dplotnikov at virtuozzo.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 c7337374678f..ef643f32ae9a 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -374,6 +374,7 @@
 #define MSR_F15H_PTSC			0xc0010280
 #define MSR_F15H_IC_CFG			0xc0011021
 #define MSR_F15H_IC_CFG_DIS_IND		BIT_ULL(14)
+#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 f1230a251add..54a8fa89ad66 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2121,6 +2121,7 @@ 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_EFER:
@@ -2387,6 +2388,7 @@ 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_K7_EVNTSEL0 ... MSR_K7_EVNTSEL3:
-- 
2.17.0