From 74a439ef7b67d89d29ec7485c3aeca20a64449c5 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Tue, 25 Jul 2023 16:37:17 +0200 Subject: [PATCH] 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 Signed-off-by: Ilya Leoshkevich Reviewed-by: Claudio Imbrenda Message-ID: <20230725143857.228626-3-iii@linux.ibm.com> Signed-off-by: Claudio Imbrenda Signed-off-by: Janosch Frank --- arch/s390/kvm/intercept.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c index 954d39a..e544967 100644 --- a/arch/s390/kvm/intercept.c +++ b/arch/s390/kvm/intercept.c @@ -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; -- 2.7.4