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/x86.c b/arch/x86/kvm/x86.c
index 7d44204..b16d4a5b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -692,6 +692,18 @@
}
EXPORT_SYMBOL_GPL(kvm_get_cr8);
+static void kvm_update_dr7(struct kvm_vcpu *vcpu)
+{
+ unsigned long dr7;
+
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)
+ dr7 = vcpu->arch.guest_debug_dr7;
+ else
+ dr7 = vcpu->arch.dr7;
+ kvm_x86_ops->set_dr7(vcpu, dr7);
+ vcpu->arch.switch_db_regs = (dr7 & DR7_BP_EN_MASK);
+}
+
static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
{
switch (dr) {
@@ -717,10 +729,7 @@
if (val & 0xffffffff00000000ULL)
return -1; /* #GP */
vcpu->arch.dr7 = (val & DR7_VOLATILE) | DR7_FIXED_1;
- if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) {
- kvm_x86_ops->set_dr7(vcpu, vcpu->arch.dr7);
- vcpu->arch.switch_db_regs = (val & DR7_BP_EN_MASK);
- }
+ kvm_update_dr7(vcpu);
break;
}
@@ -5851,13 +5860,12 @@
if (vcpu->guest_debug & 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);
+ vcpu->arch.guest_debug_dr7 = dbg->arch.debugreg[7];
} 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);
}
+ kvm_update_dr7(vcpu);
if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
vcpu->arch.singlestep_rip = kvm_rip_read(vcpu) +
@@ -5869,7 +5877,7 @@
*/
kvm_set_rflags(vcpu, rflags);
- kvm_x86_ops->set_guest_debug(vcpu, dbg);
+ kvm_x86_ops->update_db_bp_intercept(vcpu);
r = 0;
@@ -6045,10 +6053,10 @@
vcpu->arch.nmi_pending = 0;
vcpu->arch.nmi_injected = false;
- vcpu->arch.switch_db_regs = 0;
memset(vcpu->arch.db, 0, sizeof(vcpu->arch.db));
vcpu->arch.dr6 = DR6_FIXED_1;
vcpu->arch.dr7 = DR7_FIXED_1;
+ kvm_update_dr7(vcpu);
kvm_make_request(KVM_REQ_EVENT, vcpu);
vcpu->arch.apf.msr_val = 0;