linux-kernel - [tip:x86/cpu] x86/cpu/amd, kvm: Satisfy guest kernel reads of IC

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Date:	Tue, 24 Nov 2015 01:33:11 -0800
From:	tip-bot for Borislav Petkov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	luto@...capital.net, linux-kernel@...r.kernel.org,
	pbonzini@...hat.com, bp@...e.de, peterz@...radead.org,
	brgerst@...il.com, mingo@...nel.org, tglx@...utronix.de,
	dvlasenk@...hat.com, hpa@...or.com, torvalds@...ux-foundation.org,
	bp@...en8.de
Subject: [tip:x86/cpu] x86/cpu/amd, kvm:
  Satisfy guest kernel reads of IC_CFG MSR

Commit-ID:  ae8b787543d872cf89a7f9ef8aa302f3ef9bcbd7
Gitweb:     http://git.kernel.org/tip/ae8b787543d872cf89a7f9ef8aa302f3ef9bcbd7
Author:     Borislav Petkov <bp@...e.de>
AuthorDate: Mon, 23 Nov 2015 11:12:23 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 24 Nov 2015 09:15:54 +0100

x86/cpu/amd, kvm: Satisfy guest kernel reads of IC_CFG MSR

The kernel accesses IC_CFG MSR (0xc0011021) on AMD because it
checks whether the way access filter is enabled on some F15h
models, and, if so, disables it.

kvm doesn't handle that MSR access and complains about it, which
can get really noisy in dmesg when one starts kvm guests all the
time for testing. And it is useless anyway - guest kernel
shouldn't be doing such changes anyway so tell it that that
filter is disabled.

Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/msr-index.h |  1 +
 arch/x86/kernel/cpu/amd.c        |  4 ++--
 arch/x86/kvm/svm.c               | 17 +++++++++++++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 690b402..b05402e 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -321,6 +321,7 @@
 #define MSR_F15H_PERF_CTR		0xc0010201
 #define MSR_F15H_NB_PERF_CTL		0xc0010240
 #define MSR_F15H_NB_PERF_CTR		0xc0010241
+#define MSR_F15H_IC_CFG			0xc0011021
 
 /* Fam 10h MSRs */
 #define MSR_FAM10H_MMIO_CONF_BASE	0xc0010058
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index a8816b3..e229640 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -678,9 +678,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
 	 * Disable it on the affected CPUs.
 	 */
 	if ((c->x86_model >= 0x02) && (c->x86_model < 0x20)) {
-		if (!rdmsrl_safe(0xc0011021, &value) && !(value & 0x1E)) {
+		if (!rdmsrl_safe(MSR_F15H_IC_CFG, &value) && !(value & 0x1E)) {
 			value |= 0x1E;
-			wrmsrl_safe(0xc0011021, value);
+			wrmsrl_safe(MSR_F15H_IC_CFG, value);
 		}
 	}
 }
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 83a1c64..58b64c1 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3053,6 +3053,23 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	case MSR_IA32_UCODE_REV:
 		msr_info->data = 0x01000065;
 		break;
+	case MSR_F15H_IC_CFG: {
+
+		int family, model;
+
+		family = guest_cpuid_family(vcpu);
+		model  = guest_cpuid_model(vcpu);
+
+		if (family < 0 || model < 0)
+			return kvm_get_msr_common(vcpu, msr_info);
+
+		msr_info->data = 0;
+
+		if (family == 0x15 &&
+		    (model >= 0x2 && model < 0x20))
+			msr_info->data = 0x1E;
+		}
+		break;
 	default:
 		return kvm_get_msr_common(vcpu, msr_info);
 	}
--
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