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

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Date:   Mon, 17 Dec 2018 22:34:18 -0200
From:   Eduardo Habkost <ehabkost@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Brijesh Singh <brijesh.singh@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Tom Lendacky <Thomas.Lendacky@....com>,
        Babu Moger <babu.moger@....com>, linux-kernel@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: [PATCH] kvm: x86: Add AMD's EX_CFG to the list of ignored MSRs

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@...hat.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