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

Currently, after single-stepping an instruction that generates a
specification exception, GDB ends up on the instruction immediately
following it.

The reason is that vcpu_post_run() injects the interrupt and sets
KVM_GUESTDBG_EXIT_PENDING, causing a KVM_SINGLESTEP exit. The
interrupt is not delivered, however, therefore userspace sees the
address of the next instruction.

Fix by letting the __vcpu_run() loop go into the next iteration,
where vcpu_pre_run() delivers the interrupt and sets
KVM_GUESTDBG_EXIT_PENDING.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20230725143857.228626-3-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 16:37:17 +02:00 committed by Janosch Frank
parent 16631c42e6
commit 74a439ef7b
1 changed files with 16 additions and 1 deletions
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17
arch/s390/kvm/intercept.c
View File

@ -228,6 +228,21 @@ static int handle_itdb(struct kvm_vcpu *vcpu)
#define per_event(vcpu) (vcpu->arch.sie_block->iprcc & PGM_PER)
static bool should_handle_per_event(const struct kvm_vcpu *vcpu)
{
if (!guestdbg_enabled(vcpu) || !per_event(vcpu))
return false;
if (guestdbg_sstep_enabled(vcpu) &&
vcpu->arch.sie_block->iprcc != PGM_PER) {
/*
* __vcpu_run() will exit after delivering the concurrently
* indicated condition.
*/
return false;
}
return true;
}
static int handle_prog(struct kvm_vcpu *vcpu)
{
psw_t psw;
@ -242,7 +257,7 @@ static int handle_prog(struct kvm_vcpu *vcpu)
if (kvm_s390_pv_cpu_is_protected(vcpu))
return -EOPNOTSUPP;
if (guestdbg_enabled(vcpu) && per_event(vcpu)) {
if (should_handle_per_event(vcpu)) {
rc = kvm_s390_handle_per_event(vcpu);
if (rc)
return rc;