linux-kernel - [PATCH 16/40] KVM: x86: Wire-up hardware breakpoints for guest debugging

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Date:	Thu, 26 Feb 2009 16:15:06 +0200
From:	Avi Kivity <avi@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Jan Kiszka <jan.kiszka@...mens.com>
Subject: [PATCH 16/40] KVM: x86: Wire-up hardware breakpoints for guest debugging

From: Jan Kiszka <jan.kiszka@...mens.com>

Add the remaining bits to make use of debug registers also for guest
debugging, thus enabling the use of hardware breakpoints and
watchpoints.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
Signed-off-by: Avi Kivity <avi@...hat.com>
---
 arch/x86/kvm/svm.c |    5 +++++
 arch/x86/kvm/vmx.c |    5 +++++
 arch/x86/kvm/x86.c |   14 +++++++++++++-
 3 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 815f50e..b3a7a31 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -958,6 +958,11 @@ static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
 	} else
 		vcpu->guest_debug = 0;
 
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+		svm->vmcb->save.dr7 = dbg->arch.debugreg[7];
+	else
+		svm->vmcb->save.dr7 = vcpu->arch.dr7;
+
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
 		svm->vmcb->save.rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
 	else if (old_debug & KVM_GUESTDBG_SINGLESTEP)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0989776..cee81c9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1017,6 +1017,11 @@ static int set_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
 	if (!(vcpu->guest_debug & KVM_GUESTDBG_ENABLE))
 		vcpu->guest_debug = 0;
 
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+		vmcs_writel(GUEST_DR7, dbg->arch.debugreg[7]);
+	else
+		vmcs_writel(GUEST_DR7, vcpu->arch.dr7);
+
 	flags = vmcs_readl(GUEST_RFLAGS);
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
 		flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 300bc4d..2477e87 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3861,10 +3861,22 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 					struct kvm_guest_debug *dbg)
 {
-	int r;
+	int i, r;
 
 	vcpu_load(vcpu);
 
+	if ((dbg->control & (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP)) ==
+	    (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP)) {
+		for (i = 0; i < KVM_NR_DB_REGS; ++i)
+			vcpu->arch.eff_db[i] = dbg->arch.debugreg[i];
+		vcpu->arch.switch_db_regs =
+			(dbg->arch.debugreg[7] & DR7_BP_EN_MASK);
+	} else {
+		for (i = 0; i < KVM_NR_DB_REGS; i++)
+			vcpu->arch.eff_db[i] = vcpu->arch.db[i];
+		vcpu->arch.switch_db_regs = (vcpu->arch.dr7 & DR7_BP_EN_MASK);
+	}
+
 	r = kvm_x86_ops->set_guest_debug(vcpu, dbg);
 
 	if (dbg->control & KVM_GUESTDBG_INJECT_DB)
-- 
1.6.0.6

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