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Tue, 12 May 2020 16:24:27 +0000 (UTC) Date: Tue, 12 May 2020 18:24:25 +0200 From: Cornelia Huck To: Collin Walling Subject: Re: [PATCH v1 2/8] s390/sclp: check sccb len before filling in data Message-ID: <20200512182425.0ab4411c.cohuck@redhat.com> In-Reply-To: References: <20200508230823.22956-1-walling@linux.ibm.com> <20200508230823.22956-3-walling@linux.ibm.com> <58bc496c-28bb-26f8-ab46-aba6ad141717@linux.ibm.com> <737869a8-13b2-1831-00c6-629d5a109d9c@redhat.com> <05ab2e59-10c0-c7df-c014-b54883ddccd3@linux.ibm.com> <9a39a948-91a1-7cfe-f2a5-d30e5564f318@redhat.com> <20200512180140.4be69d60.cohuck@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/12 01:41:59 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Janosch Frank , mst@redhat.com, David Hildenbrand , qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, svens@linux.ibm.com, pbonzini@redhat.com, mihajlov@linux.ibm.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 12 May 2020 12:16:45 -0400 Collin Walling wrote: > On 5/12/20 12:01 PM, Cornelia Huck wrote: > > On Mon, 11 May 2020 17:02:06 +0200 > > David Hildenbrand wrote: > > > >> On 11.05.20 16:50, Janosch Frank wrote: > >>> On 5/11/20 4:44 PM, David Hildenbrand wrote: > >>>> On 11.05.20 16:36, Janosch Frank wrote: > >>>>> On 5/9/20 1:08 AM, Collin Walling wrote: > >>>>>> The SCCB must be checked for a sufficient length before it is filled > >>>>>> with any data. If the length is insufficient, then the SCLP command > >>>>>> is suppressed and the proper response code is set in the SCCB header. > >>>>>> > >>>>>> Signed-off-by: Collin Walling > >>>>> > >>>>> Fixes tag? > > > > Probably > > > > Fixes: 832be0d8a3bb ("s390x: sclp: Report insufficient SCCB length") > > > > ? > > > > Sounds reasonable. This patch doesn't fix any explicitly-known bugs > AFAIK. The s390 Linux kernel is hard-coded to use a 4K size SCCB when > executing these commands. > > I suppose this could introduce a bug if things change in the Linux > kernel or if some other OS wants to use this command. That should be > enough of a justification, right? (Just want to make sure I understand > the use of the tag correctly). Yes; from the description of how this is supposed to work it fixes architectural conformance, not a bug that is triggered by today's guest systems. [Usage of the Fixes: tag in QEMU is not quite as essential as in Linux, as we don't do the numerous, big stable updates here; I don't think this is stable material, but we can certainly record where this was introduced.]