linux-kernel - Re: x86: Hardware breakpoints are not always triggered

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Message-ID: <56AA8928.50507@redhat.com>
Date:	Thu, 28 Jan 2016 22:33:28 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Andrey Wagin <avagin@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Oleg Nesterov <oleg@...hat.com>,
	"criu@...nvz.org" <criu@...nvz.org>, kvm@...r.kernel.org
Subject: Re: x86: Hardware breakpoints are not always triggered



On 28/01/2016 09:31, Andrey Wagin wrote:
> I tried to print drX registers after a break-point. Looks like they
> are set correctly.

Can you try this KVM patch?

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c13a64b7d789..32bae1c70a50 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1612,6 +1612,7 @@ static void svm_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
 	vcpu->arch.dr7 = svm->vmcb->save.dr7;
 
 	vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_WONT_EXIT;
+	vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD;
 	set_dr_intercepts(svm);
 }
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e2951b6edbbc..505a4663b9f4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5659,6 +5659,7 @@ static void vmx_sync_dirty_debug_regs(struct kvm_vcpu *vcpu)
 	vcpu->arch.dr7 = vmcs_readl(GUEST_DR7);
 
 	vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_WONT_EXIT;
+	vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD;
 
 	cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
 	cpu_based_vm_exec_control |= CPU_BASED_MOV_DR_EXITING;

Paolo