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| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2023-07-25 16:37:19 +0200 |
|---|---|---|
| committer | Janosch Frank <frankja@linux.ibm.com> | 2023-08-28 09:24:20 +0000 |
| commit | 1ad1fa820e6424ae75d3d9f59774e40c9c7ec1e5 (patch) | |
| tree | 615f046b44d9f358f3452cc4dbaac541c0347280 /arch/s390/kvm | |
| parent | ba853a4e1c7addc631df55535bf0b04c62dc79d8 (diff) | |
| download | linux-1ad1fa820e6424ae75d3d9f59774e40c9c7ec1e5.tar.gz linux-1ad1fa820e6424ae75d3d9f59774e40c9c7ec1e5.tar.bz2 linux-1ad1fa820e6424ae75d3d9f59774e40c9c7ec1e5.zip | |
KVM: s390: interrupt: Fix single-stepping userspace-emulated instructions
Single-stepping a userspace-emulated instruction that generates an
interrupt causes GDB to land on the instruction following it instead of
the respective interrupt handler.
The reason is that after arranging a KVM_EXIT_S390_SIEIC exit,
kvm_handle_sie_intercept() calls kvm_s390_handle_per_ifetch_icpt(),
which sets KVM_GUESTDBG_EXIT_PENDING. This bit, however, is not
processed immediately, but rather persists until the next ioctl(),
causing a spurious single-step exit.
Fix by clearing this bit in ioctl().
Reviewed-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: <20230725143857.228626-5-iii@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Diffstat (limited to 'arch/s390/kvm')
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 0c6333b108ba..e6511608280c 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -5383,6 +5383,7 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp, { struct kvm_vcpu *vcpu = filp->private_data; void __user *argp = (void __user *)arg; + int rc; switch (ioctl) { case KVM_S390_IRQ: { @@ -5390,7 +5391,8 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp, if (copy_from_user(&s390irq, argp, sizeof(s390irq))) return -EFAULT; - return kvm_s390_inject_vcpu(vcpu, &s390irq); + rc = kvm_s390_inject_vcpu(vcpu, &s390irq); + break; } case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; @@ -5400,10 +5402,25 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp, return -EFAULT; if (s390int_to_s390irq(&s390int, &s390irq)) return -EINVAL; - return kvm_s390_inject_vcpu(vcpu, &s390irq); + rc = kvm_s390_inject_vcpu(vcpu, &s390irq); + break; } + default: + rc = -ENOIOCTLCMD; + break; } - return -ENOIOCTLCMD; + + /* + * To simplify single stepping of userspace-emulated instructions, + * KVM_EXIT_S390_SIEIC exit sets KVM_GUESTDBG_EXIT_PENDING (see + * should_handle_per_ifetch()). However, if userspace emulation injects + * an interrupt, it needs to be cleared, so that KVM_EXIT_DEBUG happens + * after (and not before) the interrupt delivery. + */ + if (!rc) + vcpu->guest_debug &= ~KVM_GUESTDBG_EXIT_PENDING; + + return rc; } static int kvm_s390_handle_pv_vcpu_dump(struct kvm_vcpu *vcpu, |