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Tue, 22 Sep 2026 22:15:27 +0200 (CEST) From: Eric Farman To: Christian Borntraeger , Matthew Rosato Cc: Cornelia Huck , qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Eric Farman , qemu-stable@nongnu.org Subject: [PATCH v3 8/9] s390x/css: Use datastream pointer for checking no-data CCWs Date: Tue, 22 Sep 2026 22:15:24 +0200 Message-ID: <20260922201526.2383047-9-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260922201526.2383047-1-farman@linux.ibm.com> References: <20260922201526.2383047-1-farman@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ieVtyfM_BMBOnWqHfrqvh8pgcpkWyFPk X-Authority-Analysis: v=2.4 cv=EOCTQFZC c=1 sm=1 tr=0 ts=6ab2e1e4 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=69wJf7TsAAAA:8 a=VnNF1IyMAAAA:8 a=8cHL7K5PRkdKNGgrHUUA:9 a=Fg1AiH1G6rFz08G2ETeA:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIyMDI5MyBTYWx0ZWRfX5b2STzotAgd/ sTfwYFytV3uf8dk8OA2tOGHnM2mPUatSzMPjHt5VHoqU4FedYR1l3u0q0xfwNkm/wdu9C5xDKiE JxrB4dHNMMHkhZMpuVnTVsB6M1b5YSk= X-Proofpoint-GUID: ieVtyfM_BMBOnWqHfrqvh8pgcpkWyFPk X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIyMDI5MyBTYWx0ZWRfX9ZtBXD43jWQj 2gzlFomZL/GBX0nQ84BHyfwghwC1WZCssSGtnDYeEWl2g9zwYAJg8D4At+AnilrDhSDsz4NJefv pIO9IAstzcJ0keeXlr/2ne8OdofSQsPW4kc6P0C59TulePUOPGAmdxVUriMvrYOZT8B8s5HJEfj JjmgHTpvPDAJxysA+PlsDmu0LoSbN/Q23qNSQPhQVKJ9pCi+zHU6J/1doPZ2MqGeUCBgzE4ftu1 6QZKbyGwQJUAR9OQPjD7+iIHTvguaO9zGqAAY6bC9cVlfDD5psejsZ/jY84ZYX+pJDn8m0+DAwK VMj/6aVfNyR1uijmdLLbMkVLTkKmqa4TqIaefGqCAZJ2Jxa2uHcanKLuG3apsAT6tpqYKrwa+wQ pegujA/hM7Uv+JBMeNKVGUpbuED9eMIiDyaB/RNFo8qDLGxbMgW2X5JJRWWLm/JcQE/81zD6MFi H/DN0wcFVZWdhzIl+2Q== 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=2026-09-22_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609220293 Received-SPF: pass client-ip=148.163.156.1; envelope-from=farman@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The channel subsystem will reject channel programs that incorporate 256 CCWs without a data transfer, but the existing check to account for this only does so for CCWs with a data address of zero. Other valid CCWs that wouldn't transfer data are not accounted for. Rather than re-inventing the wheel, use the output of the datastream at the end of the entire CCW parsing tree to indicate whether data was moved or not. Cc: qemu-stable@nongnu.org Fixes: e8601dd5d0 ("s390x/css: catch ccw sequence errors") Signed-off-by: Eric Farman --- hw/s390x/css.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/hw/s390x/css.c b/hw/s390x/css.c index 9da9128d88..65341c68c3 100644 --- a/hw/s390x/css.c +++ b/hw/s390x/css.c @@ -1016,13 +1016,6 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr= ccw_addr, =20 check_len =3D !((ccw.flags & CCW_FLAG_SLI) && !(ccw.flags & CCW_FLAG= _DC)); =20 - if (!ccw.cda) { - if (sch->ccw_no_data_cnt =3D=3D 255) { - return -EINVAL; - } - sch->ccw_no_data_cnt++; - } - /* Look at the command. */ ccw_dstream_init(&sch->cds, &ccw, &(sch->orb)); switch (ccw.cmd_code) { @@ -1103,6 +1096,20 @@ static int css_interpret_ccw(SubchDev *sch, hwaddr= ccw_addr, } sch->last_cmd =3D ccw; sch->last_cmd_valid =3D true; + + /* + * A CCW that transfers no data is allowed, but ensure an upper limi= t + * is established to prevent long-running channel programs that don'= t + * move actual data. + */ + if (ret =3D=3D 0 && sch->cds.at_byte =3D=3D 0) { + if (sch->ccw_no_data_cnt =3D=3D 255) { + ret =3D -EINVAL; + } else { + sch->ccw_no_data_cnt++; + } + } + if (ret =3D=3D 0) { if (ccw.flags & CCW_FLAG_CC) { sch->channel_prog +=3D 8; --=20 2.53.0