KVM: x86: DR0-DR3 are not clear on reset
DR0-DR3 are not cleared as they should during reset and when they are set from
userspace. It appears to be caused by c77fb5fe6f03 ("KVM: x86: Allow the guest
to run with dirty debug registers").
Force their reload on these situations.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Message-Id: <1427933438-12782-4-git-send-email-namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f7a78c6..ad3809d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -801,6 +801,17 @@
}
EXPORT_SYMBOL_GPL(kvm_get_cr8);
+static void kvm_update_dr0123(struct kvm_vcpu *vcpu)
+{
+ int i;
+
+ if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) {
+ for (i = 0; i < KVM_NR_DB_REGS; i++)
+ vcpu->arch.eff_db[i] = vcpu->arch.db[i];
+ vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD;
+ }
+}
+
static void kvm_update_dr6(struct kvm_vcpu *vcpu)
{
if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP))
@@ -3150,6 +3161,7 @@
return -EINVAL;
memcpy(vcpu->arch.db, dbgregs->db, sizeof(vcpu->arch.db));
+ kvm_update_dr0123(vcpu);
vcpu->arch.dr6 = dbgregs->dr6;
kvm_update_dr6(vcpu);
vcpu->arch.dr7 = dbgregs->dr7;
@@ -6323,6 +6335,7 @@
set_debugreg(vcpu->arch.eff_db[2], 2);
set_debugreg(vcpu->arch.eff_db[3], 3);
set_debugreg(vcpu->arch.dr6, 6);
+ vcpu->arch.switch_db_regs &= ~KVM_DEBUGREG_RELOAD;
}
trace_kvm_entry(vcpu->vcpu_id);
@@ -7104,6 +7117,7 @@
kvm_clear_exception_queue(vcpu);
memset(vcpu->arch.db, 0, sizeof(vcpu->arch.db));
+ kvm_update_dr0123(vcpu);
vcpu->arch.dr6 = DR6_INIT;
kvm_update_dr6(vcpu);
vcpu->arch.dr7 = DR7_FIXED_1;