linux-kernel - [PATCH v7 13/15] KVM: x86/vmx: Clear Arch LBREn bit before inject #DB to guest

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Date:   Fri,  6 Aug 2021 15:42:23 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     pbonzini@...hat.com, jmattson@...gle.com, seanjc@...gle.com,
        vkuznets@...hat.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 v7 13/15] KVM: x86/vmx: Clear Arch LBREn bit before inject #DB to guest

Per ISA spec, need to clear the bit before inject #DB.

Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 70314cd93340..31b9c06c9b3b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1601,6 +1601,21 @@ static void vmx_clear_hlt(struct kvm_vcpu *vcpu)
 		vmcs_write32(GUEST_ACTIVITY_STATE, GUEST_ACTIVITY_ACTIVE);
 }
 
+static void flip_arch_lbr_ctl(struct kvm_vcpu *vcpu, bool on)
+{
+	if (vcpu_to_pmu(vcpu)->event_count > 0 &&
+	    kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR)) {
+		u64 lbr_ctl = vmcs_read64(GUEST_IA32_LBR_CTL);
+
+		if (on)
+			lbr_ctl |= 1ULL;
+		else
+			lbr_ctl &= ~1ULL;
+
+		vmcs_write64(GUEST_IA32_LBR_CTL, lbr_ctl);
+	}
+}
+
 static void vmx_queue_exception(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -1636,6 +1651,9 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu)
 	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
 
 	vmx_clear_hlt(vcpu);
+
+	if (nr == DB_VECTOR)
+		flip_arch_lbr_ctl(vcpu, false);
 }
 
 static void vmx_setup_uret_msr(struct vcpu_vmx *vmx, unsigned int msr,
@@ -4572,6 +4590,9 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
 			INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
 
 	vmx_clear_hlt(vcpu);
+
+	if (vcpu->arch.exception.nr == DB_VECTOR)
+		flip_arch_lbr_ctl(vcpu, false);
 }
 
 bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
-- 
2.25.1