KVM: x86: Fix guest debug across vcpu INIT reset
If we reset a vcpu on INIT, we so far overwrote dr7 as provided by
KVM_SET_GUEST_DEBUG, and we also cleared switch_db_regs unconditionally.
Fix this by saving the dr7 used for guest debugging and calculating the
effective register value as well as switch_db_regs on any potential
change. This will change to focus of the set_guest_debug vendor op to
update_dp_bp_intercept.
Found while trying to stop on start_secondary.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 818fceb..d017df3 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1146,7 +1146,6 @@
svm_set_efer(&svm->vcpu, 0);
save->dr6 = 0xffff0ff0;
- save->dr7 = 0x400;
kvm_set_rflags(&svm->vcpu, 2);
save->rip = 0x0000fff0;
svm->vcpu.arch.regs[VCPU_REGS_RIP] = save->rip;
@@ -1643,7 +1642,7 @@
mark_dirty(svm->vmcb, VMCB_SEG);
}
-static void update_db_intercept(struct kvm_vcpu *vcpu)
+static void update_db_bp_intercept(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -1663,20 +1662,6 @@
vcpu->guest_debug = 0;
}
-static void svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
-{
- struct vcpu_svm *svm = to_svm(vcpu);
-
- 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;
-
- mark_dirty(svm->vmcb, VMCB_DR);
-
- update_db_intercept(vcpu);
-}
-
static void new_asid(struct vcpu_svm *svm, struct svm_cpu_data *sd)
{
if (sd->next_asid > sd->max_asid) {
@@ -1748,7 +1733,7 @@
if (!(svm->vcpu.guest_debug & KVM_GUESTDBG_SINGLESTEP))
svm->vmcb->save.rflags &=
~(X86_EFLAGS_TF | X86_EFLAGS_RF);
- update_db_intercept(&svm->vcpu);
+ update_db_bp_intercept(&svm->vcpu);
}
if (svm->vcpu.guest_debug &
@@ -3659,7 +3644,7 @@
*/
svm->nmi_singlestep = true;
svm->vmcb->save.rflags |= (X86_EFLAGS_TF | X86_EFLAGS_RF);
- update_db_intercept(vcpu);
+ update_db_bp_intercept(vcpu);
}
static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr)
@@ -4253,7 +4238,7 @@
.vcpu_load = svm_vcpu_load,
.vcpu_put = svm_vcpu_put,
- .set_guest_debug = svm_guest_debug,
+ .update_db_bp_intercept = update_db_bp_intercept,
.get_msr = svm_get_msr,
.set_msr = svm_set_msr,
.get_segment_base = svm_get_segment_base,