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Mon, 14 Sep 2026 16:43:08 +0000 (GMT) Received: from osiris (unknown [9.87.150.220]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 14 Sep 2026 16:43:08 +0000 (GMT) Date: Mon, 14 Sep 2026 18:43:06 +0200 From: Heiko Carstens To: Vineeth Vijayan Cc: wbezenah@linux.ibm.com, cohuck@redhat.com, pasic@linux.ibm.com, farman@linux.ibm.com, mjrosato@linux.ibm.com, oberpar@linux.ibm.com, linux-s390@vger.kernel.org Subject: Re: [PATCH 0/3] s390/cio: Harden pmcw/schib handling for dnv=0 Message-ID: <20260914164306.14910C66-hca@linux.ibm.com> References: <20260910093205.3357827-1-vneethv@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260910093205.3357827-1-vneethv@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE0MDIzNyBTYWx0ZWRfXz9eh7azriaTH M0y+QCGIURWQnMhZwwTjg7gEMXG4LBYT4p6ApZKsjnU0ah4D0FF3HOpHweQNnsiRLF+HXAQS2bM +JkzCkn0W1SFfOUuSTbHs4N7A0kDfY8TpIs8ZDcHIx+ba+XrgWe8A0iPRQ1VXRfq4pZH34saeyq O1PqEEHr8xjjGmkNRFOhJUem+6pVi+zBq+jMcrDS3GCrT3SuS86IZm4Hm/ZfAnpskJtF7MZKwNA QPN2lnqVFxKyjYmualkHIfdkYXOWI4L2mLeBQU7YOr4WENibB0dvkZhI8VpS4z3dZQreQyCtnXh eL7O6EkWnKr8/KX44bQZeUuCK3OcXiNCFNdKhpUZyp7nTJHTcY0pPyPAfUJKb9KFDA/R8hYIT1B HzalsoLcVvfi/umy+i6uOPCi7DSJibn8dLhCnJs+de2mnm+MDwvk8hNFoeKtVW4rCEnHfFsFG8J FePB1MXSMMf4GlTuEUA== X-Authority-Analysis: v=2.4 cv=E/NYNqdl c=1 sm=1 tr=0 ts=6aa82421 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=8nJEP1OIZ-IA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Dd6p6baFu_z_ejji7pMA:9 a=PRpDppDLrCsA:10 a=3ZKOabzyN94A:10 a=wPNLvfGTeEIA:10 X-Proofpoint-ORIG-GUID: QYfwgCmeHAVTteuuqjEWsZLm_6UeWDIF X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE0MDIzNyBTYWx0ZWRfX+qGQaTkBx3GC d1BWQ3vvPsrYigSD7Zzy7njb40u/gQ4NlOgeVjdtxFXOrwNYHvBbA/bOvCDK0sQa8WM5fVYPsPK NqqpT/y2fjyKDf6K89HWQ6JgJ8hkTTE= X-Proofpoint-GUID: QYfwgCmeHAVTteuuqjEWsZLm_6UeWDIF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-14_03,2026-09-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 bulkscore=0 malwarescore=0 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609140237 On Thu, Sep 10, 2026 at 11:32:00AM +0200, Vineeth Vijayan wrote: > For I/O subchannels, pmcw.dnv must be validated before relying on any > other PMCW or SCHIB fields. > Two issues exist today: > - Some I/O entry points check pmcw.ena without first verifying that > pmcw.dnv is set. > - cio_update_schib() updates the cached SCHIB before validating > pmcw.dnv, allowing an stsch result with dnv=0 to leave stale or > undefined data in sch->schib. >   > This can trigger spurious, non-fatal error messages in the guest kernel > log when a virtio device is being detached. >   > Fix this by validating pmcw.dnv before updating the cached SCHIB. Also > clear the cached SCHIB when stsch succeeds but returns dnv=0, ensuring > that stale state is not retained. >   > Additionally, add pmcw.dnv checks before pmcw.ena checks in I/O entry > points and return -ENODEV when no device is present. Guard remaining > direct accesses to cached PMCW fields, such as chpid[] and pam, to > ensure they are only evaluated when the SCHIB contents are valid. >   > This was reported and discussed at: >   > Link: https://lore.kernel.org/linux-s390/20260612155407.199218-1-wbezenah@linux.ibm.com/  > > Vineeth Vijayan (3): > s390/cio: Fix cio_update_schib() to not cache invalid schib > s390/cio: Check pmcw.dnv before pmcw.ena in I/O entry points > s390/cio: Guard PMCW field accesses with dnv check > > drivers/s390/cio/chp.c | 3 +++ > drivers/s390/cio/cio.c | 11 +++++++---- > drivers/s390/cio/device.c | 9 +++++---- > drivers/s390/cio/device_fsm.c | 3 +++ > drivers/s390/cio/device_ops.c | 21 +++++++++++++++++++++ > drivers/s390/cio/vfio_ccw_fsm.c | 2 +- > 6 files changed, 40 insertions(+), 9 deletions(-) Series applied, thanks!