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Message-ID: <20230721120046.2262291-3-iii@linux.ibm.com>
Date: Fri, 21 Jul 2023 13:57:55 +0200
From: Ilya Leoshkevich <iii@...ux.ibm.com>
To: Christian Borntraeger <borntraeger@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>
Cc: David Hildenbrand <david@...hat.com>,
Sven Schnelle <svens@...ux.ibm.com>, kvm@...r.kernel.org,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
Jens Freimann <jfreimann@...hat.com>,
Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v2 2/6] 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.
Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
---
arch/s390/kvm/intercept.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 954d39adf85c..7cdd927541b0 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -226,7 +226,22 @@ static int handle_itdb(struct kvm_vcpu *vcpu)
return 0;
}
-#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))
+ return false;
+ if (!(vcpu->arch.sie_block->iprcc & PGM_PER))
+ 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)
{
@@ -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;
--
2.41.0
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