Single-stepping a userspace-emulated instruction that generates an
interrupt causes GDB to land on the instruction following it instead of
the respective interrupt handler.
The reason is that after arranging a KVM_EXIT_S390_SIEIC exit,
kvm_handle_sie_intercept() calls kvm_s390_handle_per_ifetch_icpt(),
which sets KVM_GUESTDBG_EXIT_PENDING. This bit, however, is not
processed immediately, but rather persists until the next ioctl(),
causing a spurious single-step exit.
Fix by clearing this bit before KVM_EXIT_S390_SIEIC.
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
arch/s390/kvm/kvm-s390.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 0c6333b108ba..b717fb8cffed 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -5383,6 +5383,7 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
{
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
+ int rc;
switch (ioctl) {
case KVM_S390_IRQ: {
@@ -5390,7 +5391,8 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
if (copy_from_user(&s390irq, argp, sizeof(s390irq)))
return -EFAULT;
- return kvm_s390_inject_vcpu(vcpu, &s390irq);
+ rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
+ break;
}
case KVM_S390_INTERRUPT: {
struct kvm_s390_interrupt s390int;
@@ -5400,10 +5402,18 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
return -EFAULT;
if (s390int_to_s390irq(&s390int, &s390irq))
return -EINVAL;
- return kvm_s390_inject_vcpu(vcpu, &s390irq);
+ rc = kvm_s390_inject_vcpu(vcpu, &s390irq);
+ break;
}
+ default:
+ rc = -ENOIOCTLCMD;
+ break;
}
- return -ENOIOCTLCMD;
+
+ if (!rc)
+ vcpu->guest_debug &= ~KVM_GUESTDBG_EXIT_PENDING;
+
+ return rc;
}
static int kvm_s390_handle_pv_vcpu_dump(struct kvm_vcpu *vcpu,
--
2.41.0
