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Sun, 26 Jul 2026 00:01:12 +0000 (GMT) Received: from [9.61.125.201] (unknown [9.61.125.201]) by smtpav01.dal12v.mail.ibm.com (Postfix) with ESMTP; Sun, 26 Jul 2026 00:01:11 +0000 (GMT) Message-ID: <0fd76431-0ccb-4141-bf80-69afd19cdc62@linux.ibm.com> Date: Sat, 25 Jul 2026 20:01:11 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 9/9] s390/vfio_ccw: implement a crw lock To: Matthew Rosato , linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Halil Pasic , Christian Borntraeger , stable@vger.kernel.org, Farhan Ali References: <20260725152705.3958100-1-farman@linux.ibm.com> <20260725152705.3958100-10-farman@linux.ibm.com> <7a3da5de-de52-4543-8b42-a3ee344d4d95@linux.ibm.com> Content-Language: en-US From: Eric Farman Autocrypt: addr=farman@linux.ibm.com; keydata= xsFNBF7EiEwBEADGG0EtNKnjp+kQfEVqlqxXoBHjnaQptFpMgxNlz2GtqOujY6nzEWnybIXY 63XUTmMS/tWUf2DTbNCNoWwumGM/I2Gj1uGyMnc4Q477BQlL/e2/9MRaut11rwHsi4zmWylc jO0eFTSLFA8yFBj9osT3uZzk5TwWkD8sf+rD916fFVk0G39uYEd5sjEzjeOf9/dwXyZpjJY6 api1pUHEw7weRvOnllJAfIKFz+KoR6d7ezvMF9zOYHF73FGeSVIYoIEUhA5Cdg60rSlTtHb2 cftex3/cEapvY5bK3CKJ33BVVK10Bht9XfVaA/AOcg/3o5ZbhSIwz4xScGsEVf/Yr368YMdr 3VkCZrmN2ppmVRz/RvAmCyItnmzoVDlSREA6Faw6S0x8Oi7lN0cKh2hy9VPcVupraXJZrdAh GtdU+jrJvSbpdsrX8F7K3RwynbiqGrqC0izGla04hhtei/uwthatglukuxep4PknDGbzijg8 Ef7A8t3qEVklUDrsnNPN5HbR9QQdeF0HuWsDTfILbZv1MICfOK3BCDeT5mJWaJCoQ2rbuljM e1hFSt+mr7GV4h6NcBE+uGIqDSzQORtyTo0uBV4et3cSE84JxOfXBMrj0TlL1855JaIoPWEN uhDRB/dHW8+Fumq2du5hLcaXPka+MO26cNVKVLF0/JjwMTZ9bQARAQABzSJFcmljIEZhcm1h biA8ZmFybWFuQGxpbnV4LmlibS5jb20+wsGuBBMBCABYAhsDBwsJCAcDAgEGFQgCCQoLBBYC AwECHgECF4AdGGh0dHBzOi8va2V5c2VydmVyLnVidW50dS5jb20WIQTSxgUEyej1aM/lh7U4 J7IScb+VYgUCYel8TgAKCRA4J7IScb+VYsHAD/9BSQj7HeJf90PttOmVh35Bb4QyHLZ4g+9x waM59JCKGbiURuNRIGnoRarYXHk6vfy19v8v56Dy1IOlKWaRnizp5Mw9zXBBTCs4fgNbOzY/ SggFY2UzcziXDG29X9zznq5LgY1Jf/cwm1O+rn89GKCZWZhLEB2wKzBj7hum7NBdW+lxfVwp 2qONGDerttWDwAHxJ995k9aDJahq9kIKEMEZbrTQ8JI8KZGoox6+HA04EhoNzxvbV0J+/gLJ 2DkvxN5/xmcD3z+s8B5ev3NarOF17AIA9oCdfu8CPAupcNqJW86m19P5q6AyRB2ZLyAIAAhr HCXrnlh/8HJW1yCOVXxprFdpg1SX1fuArjbFAh53vVVDfkZlwHeTeE7+3y1rtDLfy830pqdD ymv94yey2y1+iZBdbaW0fSC/JkjkOCy8oZawkH3geM4MXV4ze4gbBH6BhxW/0gbEYjnLm3FA 53JcXwhHQFPWIYEYYPvATJi0JUiMY1Znkm3QBWDOCXSrG0tHpAclBa9L40zLRwA1h9YOMFEs qvKijUdvcDf4sTdJ+A6YL66grzul5vNt06NlqsI8HUDHE6vghqyWxupCav2+9b1BuLie++er b8OCo5n3TUHsVMjYJEePU1EkcCa84dCm+CXqPthgRv0sbe4UQEd/qUoVMdWj7Q7FL96mBn0G zM7BTQRexIhMARAAp+k1sC4y7Wtwjqtfu9wIihvY/Vot0v/sKg8CRGRIIRGLiCeA9o+2ZlxC jYztT3Leri5Vo5z09OmRMvoFLJjcHMCG5sYeZwOWNAbeuAxGkIMDSB4pLl3t2c+1PQuMBCd7 +mRZFaMEJfT3nhdUKxy2rp1+YucnA67xGXUJCiD5l9UmhPqa7SAYlpMAqDz7cmBo25c/UNm1 Tpwjrh70jq/4guV5gnprawH8nkRjdKH1JvKWvkuaB7FNZ9IuSHlWclcQX4IQMsaxsU2emAbP VYv7l4YNlKfdlJd8tuEodjuMLOBnr7e9H0hVNUWGFN9bkBNRu3zi/jvhyu15Iu4euR/WdVNu 2K2iYxIfiGMnv0F/a6R1bm10lCJrjyf23J8DYIeH4YmHvOOqYFkq3DWOctlXbb3+aABqjYt3 mkiOLXeplqbo/m3rWcGNd8Q/d1aVA0wm5+Nt3RdSuXG2FHOFdVUQKPLpf1NUH/LInBhS/9Ys ajm6tWXKv7hxwWmyz0u/th6gUra3KpARB1ypebWHULLNzKGwVS81XNs76QhXwX04cyiwLqKb WqLqJKThz+rLa09Ap+eO/UzPfFXvWYWfTeFRIQ/tKF332ZzRR8Xrh/fk//YXyRfpoE/7i5uz ve0HZWp5jXg9Yb+S6g0+XUKznnN9B8WLLCcuRIuSa722070v7KsAEQEAAcLBdgQYAQgAIAIb DBYhBNLGBQTJ6PVoz+WHtTgnshJxv5ViBQJh6XwwAAoJEDgnshJxv5Vib28P/1BYT5gvjuEB A80AXo/IqycicXxDJtrfmyw4COP7bi7AuiDcKyA1wRzC51paKwPFB8Unk2GvG4DV6aDmGTJY +GeCYgthQ+znW461S8B6GqDCAQt2VDNNFVU+gTuh7vYQOgt/OjtiiAvMIJBVRbXoNSRokKOF tpTiXf3ZOsAkot5ZmxE0TV94v18sp/bC84YvFyaxpw5bilT7bmpcq8B8/3yb0kmy6gXLcQAp OnomV3sQBmm050amiO3tvxMNv8J71AvNdTG/rojTDKUl2Nw4f+aw4nVw874m2XpEe9JGRw54 5d2dN8k3GpzcTBe9fCQPOFHOGkQ1CgptDkQuQVD3DIeNzQjXf6xehEymIKnLOkukT2smV0zh fj08z7eiv+dsmnBsbhdM6DKU8qIgkTu77TfHUKjjOY/Mj0YHPuH/J4b1AZFxBhGP0BTKiB2W CR6/49XVKvY1jHxgadSSNCD+f7tEqUNBlVl+P0emMJaYpK1+gy88ma4g3nvyOVe/VzDPjGDC 4HX/6RAR4Dbzry6/epWTTji+7ApzePzmJzPcuzD31ICsgT2dJ6ydxyxxXikBFJqx6BPOF+u+ 1BtKcTz1ek3I2sWvBM1V5CKaFw7iNXxS6HgS2scuAT2awKq+BQlt778/GfBWpXonfqixMvit y8m0x6unNti2MZIUMy0m2gcE In-Reply-To: <7a3da5de-de52-4543-8b42-a3ee344d4d95@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 36iVbkSlFHpU7jjuuHE7nyXSfmyKXOqG X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI1MDIyNiBTYWx0ZWRfX2RG+W19wtOrq jJtPamSAOp5pwxubDBqtbYNxj7OEh5dtEJuvOsH8PqZ/nikuzjTT0F0uzM6KIdsOMqKJViOWYKv tuK0b/S2zsdBdfPEAvfvgYdggjNBt6s= X-Authority-Analysis: v=2.4 cv=E/z9Y6dl c=1 sm=1 tr=0 ts=6a654e4b cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=9LUc9bIMTqo9_Lqi4y0A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI1MDIyNiBTYWx0ZWRfX70Iyzb8HIbci +xyGkE2UOMpA/oGnLyFY//vPWvtHANEdD8hiBvIwyKPoC61hrUtXojr8fDkcXbUdKF+1IGS2tdU eEcjrUwBQUBYhdkmaD6cdQT0Agy58p4K47RVdw5ifA7idGUsn2FBa00qEQ8vTOBdEkdJ4/mTG/O 4pUjztqEuwUlIh5DOmHgS3wPwxs3rZeVpKUdR0INcfbSGRKq+GzoPNN13voK9RvsNDMMVYYa5k0 U0EG/dZxWB8mkU1eYrK1iF0PNIF7t8lrpRDCnzk8LknjMr51cYN5pEdTSn8zHbOJIgXeeSjTXZh 74yUZJtnAy0r0vPslwzbx6pR+0FGYnzkelrUauTFi+oNrugzy/kzFpl97cp8iV+o0NwePy+ZUew mzEbGqOG5db8lD6bviZPoC6HmCift3mcN9TOgFJ8gRqG/yXKMowCvKfRXT8VcjeGcfmZTkVor9i TV936mDj6XLuGQe7nYg== X-Proofpoint-GUID: 36iVbkSlFHpU7jjuuHE7nyXSfmyKXOqG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-25_07,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 spamscore=0 clxscore=1015 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607250226 On 7/25/26 1:03 PM, Matthew Rosato wrote: > On 7/25/26 11:27 AM, Eric Farman wrote: >> Unlike the channel_program struct, which covers synchronous I/O >> submissions and asynchronous interrupts, the CRW region relies >> exclusively on asynchronous events coming from hardware. >> >> Implement a lock to manage the list of those payloads, to ensure >> they are read cohesively. >> >> Fixes: 3f02cb2fd9d2 ("vfio-ccw: Wire up the CRW irq and CRW region") >> Cc: stable@vger.kernel.org >> Cc: Farhan Ali >> Signed-off-by: Eric Farman > > ... > >> --- a/drivers/s390/cio/vfio_ccw_private.h >> +++ b/drivers/s390/cio/vfio_ccw_private.h >> @@ -98,6 +98,8 @@ struct vfio_ccw_parent { >> * @cp: channel program for the current I/O operation >> * @irb: irb info received from interrupt >> * @scsw: scsw info >> + * @crw_lock: serialization of CRW information > > I would re-word this to say 'CRW list', to make it a bit more clear that > the lock does not protect crw_trigger at this time (as discussed in v3). Yeah, good call. > > With that: > > Reviewed-by: Matthew Rosato Thanks, > > >> + * @crw: list of Channel Report Word elements >> * @io_trigger: eventfd ctx for signaling userspace I/O results >> * @crw_trigger: eventfd ctx for signaling userspace CRW information >> * @req_trigger: eventfd ctx for signaling userspace to return device >> @@ -122,6 +124,8 @@ struct vfio_ccw_private { >> >> struct irb irb; >> union scsw scsw; >> + >> + spinlock_t crw_lock; >> struct list_head crw; >> >> struct eventfd_ctx *io_trigger; >