linux-kernel - [PATCH v5 06/13] KVM: x86/vmx: Save/Restore host MSR_ARCH_LBR

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Date:   Fri,  9 Jul 2021 18:05:04 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        jmattson@...gle.com, wei.w.wang@...el.com, like.xu.linux@...il.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Yang Weijiang <weijiang.yang@...el.com>
Subject: [PATCH v5 06/13] KVM: x86/vmx: Save/Restore host MSR_ARCH_LBR_CTL state

If host is using MSR_ARCH_LBR_CTL then save it before vm-entry
and reload it after vm-exit.

Co-developed-by: Like Xu <like.xu@...ux.intel.com>
Signed-off-by: Like Xu <like.xu@...ux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++++++++
 arch/x86/kvm/vmx/vmx.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 1a79ac1757af..0d714e76e2d5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1397,6 +1397,26 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu,
 		decache_tsc_multiplier(vmx);
 }
 
+static inline unsigned long get_lbrctlmsr(void)
+{
+	unsigned long lbrctlmsr = 0;
+
+	if (!static_cpu_has(X86_FEATURE_ARCH_LBR))
+		return 0;
+
+	rdmsrl(MSR_ARCH_LBR_CTL, lbrctlmsr);
+
+	return lbrctlmsr;
+}
+
+static inline void update_lbrctlmsr(unsigned long lbrctlmsr)
+{
+	if (!static_cpu_has(X86_FEATURE_ARCH_LBR))
+		return;
+
+	wrmsrl(MSR_ARCH_LBR_CTL, lbrctlmsr);
+}
+
 /*
  * Switches to specified vcpu, until a matching vcpu_put(), but assumes
  * vcpu mutex is already taken.
@@ -1410,6 +1430,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	vmx_vcpu_pi_load(vcpu, cpu);
 
 	vmx->host_debugctlmsr = get_debugctlmsr();
+	vmx->host_lbrctlmsr = get_lbrctlmsr();
 }
 
 static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
@@ -6797,6 +6818,8 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
 	/* MSR_IA32_DEBUGCTLMSR is zeroed on vmexit. Restore it if needed */
 	if (vmx->host_debugctlmsr)
 		update_debugctlmsr(vmx->host_debugctlmsr);
+	if (vmx->host_lbrctlmsr)
+		update_lbrctlmsr(vmx->host_lbrctlmsr);
 
 #ifndef CONFIG_X86_64
 	/*
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index cc362e2d3eaa..69e243fea23d 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -328,6 +328,7 @@ struct vcpu_vmx {
 	u64 current_tsc_ratio;
 
 	unsigned long host_debugctlmsr;
+	unsigned long host_lbrctlmsr;
 
 	/*
 	 * Only bits masked by msr_ia32_feature_control_valid_bits can be set in
-- 
2.21.1