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KVM: s390: interrupt: Fix single-stepping into interrupt handlers

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After single-stepping an instruction that generates an interrupt, GDB
ends up on the second instruction of the respective interrupt handler.

The reason is that vcpu_pre_run() manually delivers the interrupt, and
then __vcpu_run() runs the first handler instruction using the
CPUSTAT_P flag. This causes a KVM_SINGLESTEP exit on the second handler
instruction.

Fix by delaying the KVM_SINGLESTEP exit until after the manual
interrupt delivery.

Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20230725143857.228626-2-iii@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
This commit is contained in:
Ilya Leoshkevich 2023-07-25 16:37:16 +02:00 committed by Janosch Frank
parent ede6d0b203
commit 16631c42e6
2 changed files with 16 additions and 2 deletions
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14
arch/s390/kvm/interrupt.c
View File

@ -1392,6 +1392,7 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
{
struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
int rc = 0;
bool delivered = false;
unsigned long irq_type;
unsigned long irqs;
@ -1465,6 +1466,19 @@ int __must_check kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)
WARN_ONCE(1, "Unknown pending irq type %ld", irq_type);
clear_bit(irq_type, &li->pending_irqs);
}
delivered |= !rc;
}
/*
* We delivered at least one interrupt and modified the PC. Force a
* singlestep event now.
*/
if (delivered && guestdbg_sstep_enabled(vcpu)) {
struct kvm_debug_exit_arch *debug_exit = &vcpu->run->debug.arch;
debug_exit->addr = vcpu->arch.sie_block->gpsw.addr;
debug_exit->type = KVM_SINGLESTEP;
vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING;
}
set_intercept_indicators(vcpu);

4
arch/s390/kvm/kvm-s390.c
View File

@ -4611,7 +4611,7 @@ static int vcpu_pre_run(struct kvm_vcpu *vcpu)
if (!kvm_is_ucontrol(vcpu->kvm)) {
rc = kvm_s390_deliver_pending_interrupts(vcpu);
if (rc)
if (rc || guestdbg_exit_pending(vcpu))
return rc;
}
@ -4738,7 +4738,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
do {
rc = vcpu_pre_run(vcpu);
if (rc)
if (rc || guestdbg_exit_pending(vcpu))
break;
kvm_vcpu_srcu_read_unlock(vcpu);