Commit 16631c42 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Janosch Frank
Browse files

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



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: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Message-ID: <20230725143857.228626-2-iii@linux.ibm.com>
Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent ede6d0b2

arch/s390/kvm/interrupt.c

+14 −0
Original line number Diff line number Diff line
@@ -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);

arch/s390/kvm/kvm-s390.c

+2 −2
Original line number Diff line number Diff line
@@ -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);