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Sat, 25 Jul 2026 11:21:59 +0000 (GMT) Received: from [9.61.19.212] (unknown [9.61.19.212]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Sat, 25 Jul 2026 11:21:59 +0000 (GMT) Message-ID: <51955778-de09-4d1d-88d3-23d067b9f051@linux.ibm.com> Date: Sat, 25 Jul 2026 07:21:59 -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 v3 8/8] 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: <20260723174751.1180334-1-farman@linux.ibm.com> <20260723174751.1180334-9-farman@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: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI1MDEwNiBTYWx0ZWRfXxWZrPKOy3zN/ tSyv5nsUXj/ATcZPS+JkhqTxCYR+4KtdJK09MC85Jpm1lz+/aAj4cpFhTy2iHhHNkTqb7RUpgji 9HpFg/2K7ugewrLMlKwHtWxk0zP/b5U= X-Proofpoint-GUID: DeWSjaMXnJzELSIqpWCWrlwXhtOoscow X-Proofpoint-ORIG-GUID: DeWSjaMXnJzELSIqpWCWrlwXhtOoscow X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI1MDEwNiBTYWx0ZWRfXxKUBZLcvlsYg H8r6JMm+vKvUdmcQzZZ1qVENmJ26Xik+XXDz3jWZFGbmfq3YAVlb7EEFo3PV/zKGSaw+YVwLSNh B7WzZHKjOH3RCYyVVCpe5VDzayvIhhpl61y66wFPBnFMiPRSo4x7ojqZ4SkffwFJpl3DKEM/lpJ /kqZQ9HsYPEZ0HV/zL640nj5HpJo24ytxQkeHrUXsFK/m5mSV88OFy14QflKBcN1/u4zmi4vbVL YgXsq+qJjAvm+e1LVwQCUS/M3nd1uCfo0dY4GyDERGNZtdGy2yUlpv1vxZKT07og5rN4c5kE+eg L/6RxI8dYBCQJyoN/tuXyKlIVkgJayoLt0GvUubmXRP+kwD8nB2L/OH8kMVXp1IiHJYFUbR1ayy 2/LhhAyKByFbuixVk3h0MVOfyqBR0K26B+AtEkW/tInFc1DUEOQpDcWyowgpm2t56BV8O4kC7S2 t5rz+q2TIv/PMReY/lQ== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a649c5a cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=M55gZVjYqC4F6Pnyi9kA:9 a=QEXdDO2ut3YA:10 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_03,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607250106 On 7/24/26 4:44 PM, Matthew Rosato wrote: > On 7/23/26 1:47 PM, 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 >> --- >> drivers/s390/cio/vfio_ccw_chp.c | 17 +++++++++++------ >> drivers/s390/cio/vfio_ccw_drv.c | 4 ++++ >> drivers/s390/cio/vfio_ccw_ops.c | 3 +++ >> drivers/s390/cio/vfio_ccw_private.h | 2 ++ >> 4 files changed, 20 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/s390/cio/vfio_ccw_chp.c b/drivers/s390/cio/vfio_ccw_chp.c >> index bf678270c457..3d05aaf790fa 100644 >> --- a/drivers/s390/cio/vfio_ccw_chp.c >> +++ b/drivers/s390/cio/vfio_ccw_chp.c >> @@ -93,15 +93,19 @@ static ssize_t vfio_ccw_crw_region_read(struct vfio_ccw_private *private, >> if (pos + count > sizeof(*region)) >> return -EINVAL; >> >> + mutex_lock(&private->io_mutex); >> + i = array_index_nospec(i, private->num_regions); > > Same comment as patch 6 wrt to array_index_nospec > > ... > >> index ac5aaa78a74b..2562679b5ef5 100644 >> --- a/drivers/s390/cio/vfio_ccw_private.h >> +++ b/drivers/s390/cio/vfio_ccw_private.h >> @@ -121,6 +121,8 @@ struct vfio_ccw_private { >> >> struct irb irb; >> union scsw scsw; >> + >> + spinlock_t crw_lock; > > This should have a comment either here or, in keeping with the rest of > the struct, in the comment block above. Thanks, missed that. The crw field itself was never added to the comment block, so I'll add that as well. Similarly, I didn't add definitions for the new fields in struct channel_program earlier in this series, so I've gone back and done those. > > This looks good if you're trying to protect private->crw list, I don't > think it's complete if you're also trying to protect > private->crw_trigger - it looks to me like you hold the new lock over > most accesses to crw_trigger but at least not vfio_ccw_mdev_set_irqs > where you set/clear it. I suspect you're right that crw_trigger needs some love and be moved under this umbrella, but I'm drawing the line at private->crw for the now. > > >> struct list_head crw; >> >> struct eventfd_ctx *io_trigger; >