From: Xiaoyao Li <xiaoyao.li@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
kvm@vger.kernel.org
Cc: Nadav Amit <namit@cs.technion.ac.il>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
linux-kernel@vger.kernel.org, Xiaoyao Li <xiaoyao.li@intel.com>
Subject: [RFC PATCH 3/3] kvm: x86: skip DRn reload if previous VM exit is DR access VM exit
Date: Thu, 16 Apr 2020 18:15:09 +0800 [thread overview]
Message-ID: <20200416101509.73526-4-xiaoyao.li@intel.com> (raw)
In-Reply-To: <20200416101509.73526-1-xiaoyao.li@intel.com>
When DR access vm exit, there is no DRn change throughout VM exit to
next VM enter. Skip the DRn reload in this case and fix the comments.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
arch/x86/kvm/svm/svm.c | 8 +++++---
arch/x86/kvm/vmx/vmx.c | 8 +++++---
arch/x86/kvm/x86.c | 2 +-
3 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 66123848448d..c6883a0bf8c3 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2287,9 +2287,11 @@ static int dr_interception(struct vcpu_svm *svm)
if (svm->vcpu.guest_debug == 0) {
/*
- * No more DR vmexits; force a reload of the debug registers
- * and reenter on this instruction. The next vmexit will
- * retrieve the full state of the debug registers.
+ * No more DR vmexits and reenter on this instruction.
+ * The next vmexit will retrieve the full state of the debug
+ * registers and re-enable DR vmexits.
+ * No need to set KVM_DEBUGREG_NEED_RELOAD because no DRn change
+ * since this DR vmexit.
*/
clr_dr_intercepts(svm);
svm->vcpu.arch.switch_db_regs |= KVM_DEBUGREG_WONT_EXIT;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index aa1b8cf7c915..22eff8503048 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4967,9 +4967,11 @@ static int handle_dr(struct kvm_vcpu *vcpu)
exec_controls_clearbit(to_vmx(vcpu), CPU_BASED_MOV_DR_EXITING);
/*
- * No more DR vmexits; force a reload of the debug registers
- * and reenter on this instruction. The next vmexit will
- * retrieve the full state of the debug registers.
+ * No more DR vmexits and reenter on this instruction.
+ * The next vmexit will retrieve the full state of the debug
+ * registers and re-enable DR vmexits.
+ * No need to set KVM_DEBUGREG_NEED_RELOAD because no DRn change
+ * since this DR vmexit.
*/
vcpu->arch.switch_db_regs |= KVM_DEBUGREG_WONT_EXIT;
return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 71264df64001..8983848cbf45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8400,7 +8400,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (test_thread_flag(TIF_NEED_FPU_LOAD))
switch_fpu_return();
- if (unlikely(vcpu->arch.switch_db_regs)) {
+ if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_NEED_RELOAD)) {
set_debugreg(0, 7);
set_debugreg(vcpu->arch.eff_db[0], 0);
set_debugreg(vcpu->arch.eff_db[1], 1);
--
2.20.1
next prev parent reply other threads:[~2020-04-16 10:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 10:15 [RFC PATCH 0/3] kvm: x86: Cleanup and optimazation of switch_db_regs Xiaoyao Li
2020-04-16 10:15 ` [RFC PATCH 1/3] kvm: x86: Rename KVM_DEBUGREG_RELOAD to KVM_DEBUGREG_NEED_RELOAD Xiaoyao Li
2020-04-23 19:09 ` Sean Christopherson
2020-04-24 13:28 ` Xiaoyao Li
2020-04-24 20:21 ` Peter Xu
2020-04-24 20:29 ` Sean Christopherson
2020-04-24 20:59 ` Peter Xu
2020-04-25 7:48 ` Paolo Bonzini
2020-04-27 14:37 ` Peter Xu
2020-04-27 16:06 ` Xiaoyao Li
2020-04-25 8:07 ` Paolo Bonzini
2020-04-25 16:54 ` Nadav Amit
2020-04-25 19:16 ` Paolo Bonzini
2020-04-16 10:15 ` [RFC PATCH 2/3] kvm: x86: Use KVM_DEBUGREG_NEED_RELOAD instead of KVM_DEBUGREG_BP_ENABLED Xiaoyao Li
2020-04-23 19:29 ` Sean Christopherson
2020-04-24 13:21 ` Xiaoyao Li
2020-04-16 10:15 ` Xiaoyao Li [this message]
2020-04-23 19:31 ` [RFC PATCH 3/3] kvm: x86: skip DRn reload if previous VM exit is DR access VM exit Sean Christopherson
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