linux-kernel - [PATCH] KVM: x86: trap AMD MSRs for the TSeg base and mask

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Date:	Fri, 18 Sep 2015 17:34:24 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	luto@...capital.net, bp@...en8.de, konrad.wilk@...cle.com,
	crobinso@...hat.com, xen-devel@...ts.xensource.com,
	m.a.young@...ham.ac.uk, xen@...ts.fedoraproject.org
Subject: [PATCH] KVM: x86: trap AMD MSRs for the TSeg base and mask

These have roughly the same purpose as the SMRR, which we do not need
to implement in KVM.  However, Linux accesses MSR_K8_TSEG_ADDR at
boot, which causes problems when running a Xen dom0 under KVM.
Just return 0, meaning that processor protection of SMRAM is not
in effect.

Signed-off-by: Paolo Bonzini <pbonzini@...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 c1c0a1c14344..b98b471a3b7e 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -331,6 +331,7 @@
 /* C1E active bits in int pending message */
 #define K8_INTP_C1E_ACTIVE_MASK		0x18000000
 #define MSR_K8_TSEG_ADDR		0xc0010112
+#define MSR_K8_TSEG_MASK		0xc0010113
 #define K8_MTRRFIXRANGE_DRAM_ENABLE	0x00040000 /* MtrrFixDramEn bit    */
 #define K8_MTRRFIXRANGE_DRAM_MODIFY	0x00080000 /* MtrrFixDramModEn bit */
 #define K8_MTRR_RDMEM_WRMEM_MASK	0x18181818 /* Mask: RdMem|WrMem    */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6bbb0dfb99d0..991466bf8dee 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2190,6 +2190,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_LASTINTFROMIP:
 	case MSR_IA32_LASTINTTOIP:
 	case MSR_K8_SYSCFG:
+	case MSR_K8_TSEG_ADDR:
+	case MSR_K8_TSEG_MASK:
 	case MSR_K7_HWCR:
 	case MSR_VM_HSAVE_PA:
 	case MSR_K8_INT_PENDING_MSG:
-- 
1.8.3.1

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