KVM: x86: Wire-up hardware breakpoints for guest debugging

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@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 23 insertions, 1 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 815f50e425ac..b3a7a314d55c 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 0989776ee7b0..cee81c9a6653 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 300bc4d42abc..2477e87b2f84 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)