From: Like Xu <like.xu@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/2] KVM: vmx/pmu: Clear DEBUGCTLMSR_LBR bit on the debug breakpoint event
Date: Tue, 23 Feb 2021 09:39:58 +0800 [thread overview]
Message-ID: <20210223013958.1280444-2-like.xu@linux.intel.com> (raw)
In-Reply-To: <20210223013958.1280444-1-like.xu@linux.intel.com>
When the processor that support model-specific LBR generates a debug
breakpoint event, it automatically clears the LBR flag. This action
does not clear previously stored LBR stack MSRs. (Intel SDM 17.4.2)
Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
arch/x86/kvm/vmx/vmx.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e0a3a9be654b..4951b535eb7f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4795,6 +4795,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
u32 intr_info, ex_no, error_code;
unsigned long cr2, rip, dr6;
u32 vect_info;
+ u64 lbr_ctl;
vect_info = vmx->idt_vectoring_info;
intr_info = vmx_get_intr_info(vcpu);
@@ -4886,6 +4887,10 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
rip = kvm_rip_read(vcpu);
kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
kvm_run->debug.arch.exception = ex_no;
+ /* On the debug breakpoint event, the LBREn bit is cleared. */
+ lbr_ctl = vmcs_read64(GUEST_IA32_DEBUGCTL);
+ if (lbr_ctl & DEBUGCTLMSR_LBR)
+ vmcs_write64(GUEST_IA32_DEBUGCTL, lbr_ctl & ~DEBUGCTLMSR_LBR);
break;
case AC_VECTOR:
if (guest_inject_ac(vcpu)) {
--
2.29.2
next prev parent reply other threads:[~2021-02-23 1:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 1:39 [PATCH 1/2] KVM: vmx/pmu: Fix dummy check if lbr_desc->event is created Like Xu
2021-02-23 1:39 ` Like Xu [this message]
2021-02-23 16:38 ` [PATCH 2/2] KVM: vmx/pmu: Clear DEBUGCTLMSR_LBR bit on the debug breakpoint event Sean Christopherson
2021-02-23 17:06 ` Paolo Bonzini
2021-02-23 17:06 ` [PATCH 1/2] KVM: vmx/pmu: Fix dummy check if lbr_desc->event is created Paolo Bonzini
2021-02-23 17:15 ` Sean Christopherson
2021-02-23 17:19 ` Paolo Bonzini
2021-02-24 2:29 ` Xu, Like
2021-02-26 22:46 ` Sean Christopherson
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