[PATCH v4 3/4] KVM: s390: avoid kvm_s390_handle_pv() error overwrite

Suren Baghdasaryan
2026-03-22T05:43:39Z

If kvm_s390_handle_pv() call fails its error code gets recorded but
execution proceeds as if the call was successful. If the next call to
copy_to_user() fails then the original error is overwritten.
The follow-up patch adds fatal signal checks during VMA walk, which
makes it possible for kvm_s390_handle_pv() to return EINTR error.
Without this fix any error including EINTR can be overwritten and
original error will be lost.

Change error handling for kvm_s390_handle_pv() to alter normal flow
once failure happens. This is consistent with how kvm_arch_vm_ioctl
handles errors for other ioctl commands.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
arch/s390/kvm/kvm-s390.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 3eb60aa932ec..ddad08c0926f 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2947,6 +2947,8 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
}
/* must be called without kvm->lock */
r = kvm_s390_handle_pv(kvm, &args);
+ if (r)
+ break;
if (copy_to_user(argp, &args, sizeof(args))) {
r = -EFAULT;
break;
--
2.53.0.1018.g2bb0e51243-goog