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b=bV7mxTWBukFmR5V1TfAE3U4PHdCw+B18jcmZLFiYDg7lovpoVi6W/EcoLDOyawoWb c0G+I1soK0HNQ46qHJ+Kjhzxtr3DmCXIVcBDdGHe7lZgMwdP8lE4dOiU+1frxh5Oxk tg1wgR+cFyGJUFixQBX2maEdDM0hOlThkIbVZFptqw91KGyr/5gFVsKpksHc8l7FYm Zch52RON9+hDZ0Z7iCImIZ9bbmdEUsIctlSMiYO8s9e9QpKd6up+CSD0A/rQcEGzcG /9mMQ/b/RZUqQx95MmexN/E+miQtL0jHPA0oXOyJeIypJzez/ho+OREMjiHEL+dFS5 JqIYFBD77kcJQ== Date: Mon, 23 Mar 2026 17:53:21 +0000 From: "Lorenzo Stoakes (Oracle)" To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, willy@infradead.org, david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, lorenzo.stoakes@oracle.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, vbabka@suse.cz, jannh@google.com, rppt@kernel.org, mhocko@suse.com, pfalcato@suse.de, kees@kernel.org, maddy@linux.ibm.com, npiggin@gmail.com, mpe@ellerman.id.au, chleroy@kernel.org, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, gerald.schaefer@linux.ibm.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v4 3/4] KVM: s390: avoid kvm_s390_handle_pv() error overwrite Message-ID: References: <20260322054309.898214-1-surenb@google.com> <20260322054309.898214-4-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260322054309.898214-4-surenb@google.com> X-Rspam-User: X-Rspamd-Queue-Id: 5D9C420004 X-Stat-Signature: 7f3bos9zs66a917ub1kfkk5xnbr8431j X-Rspamd-Server: rspam06 X-HE-Tag: 1774288404-260754 X-HE-Meta: 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 s6CkvPbz H5CHAbNBRRXLwHSogszDz3bNG0v0NUukCe4kLpXADmeUL3c2LMxoBer6mpoGwMBOmQojp78Dwe74RccXckzA9d5Cqnl55niLVNG7RRtLLV0YMhOtvwoAKr9ozGnYuYQmNgQ0B1lFoL63nsvl/1o5RXR4RjOlI0py4fvc3v1PSs13MZs63w8GulT3h0FhLuWjrn3XBCjh4+2UDK+Y3UKH9KVvfxKG61x+HlcQkP8rcS7kzf9PNmZF7YB6RvFpUUZyez+p3JUt7wACKHFogxBlhg/1jld68fu1rF9GYepVagiY4H3VCgorRLJBXKwqXA+ZvftSBhSpTHB3nyHAWoXIjwzBTN/I2kV9P6Ww5X7g3DU+GZbA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Mar 21, 2026 at 10:43:07PM -0700, Suren Baghdasaryan wrote: > 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. Is that really a big deal though, as you're returning an error in either case? > 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 > --- > 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))) { Yeah as per Sashiko we probably need to copy_to_user() still. But in that case, do we even need a change at all? I'm not sure it really matters which error code terminates things does it? > r = -EFAULT; > break; > -- > 2.53.0.1018.g2bb0e51243-goog > Thanks, Lorenzo