linux-kernel - [PATCH v9 06/17] KVM: x86: Add Arch LBR MSRs to msrs_to_save

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Message-Id: <20220215212544.51666-7-weijiang.yang@intel.com>
Date:   Tue, 15 Feb 2022 16:25:33 -0500
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     pbonzini@...hat.com, jmattson@...gle.com, seanjc@...gle.com,
        like.xu.linux@...il.com, vkuznets@...hat.com, wei.w.wang@...el.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Yang Weijiang <weijiang.yang@...el.com>
Subject: [PATCH v9 06/17] KVM: x86: Add Arch LBR MSRs to msrs_to_save_all list

Arch LBR MSR_ARCH_LBR_DEPTH and MSR_ARCH_LBR_CTL are queried by
userspace application before it wants to {save|restore} the Arch LBR
data. Other LBR related data MSRs are omitted here intentionally due
to lengthy list(32*3). Userspace can still use KVM_{GET|SET}_MSRS to
access them if necessary.

Suggested-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/x86.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8891329d594c..5d8a0364a3cc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1394,6 +1394,7 @@ static const u32 msrs_to_save_all[] = {
 	MSR_F15H_PERF_CTR3, MSR_F15H_PERF_CTR4, MSR_F15H_PERF_CTR5,
 	MSR_IA32_XFD, MSR_IA32_XFD_ERR,
 	MSR_IA32_XSS,
+	MSR_ARCH_LBR_CTL, MSR_ARCH_LBR_DEPTH,
 };
 
 static u32 msrs_to_save[ARRAY_SIZE(msrs_to_save_all)];
@@ -6634,6 +6635,11 @@ static void kvm_init_msr_list(void)
 			if (!supported_xss)
 				continue;
 			break;
+		case MSR_ARCH_LBR_DEPTH:
+		case MSR_ARCH_LBR_CTL:
+			if (!kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR))
+				continue;
+			break;
 		default:
 			break;
 		}
-- 
2.27.0