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Mon, 26 Jan 2026 21:01:11 +0000 (GMT) Message-ID: <344d4e1c57d2eeb750b0c0edf12d88eb31e05ed0.camel@linux.ibm.com> Subject: Re: [PATCH v8 3/9] PCI: Avoid saving config space state if inaccessible From: Niklas Schnelle To: Farhan Ali , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Cc: helgaas@kernel.org, lukas@wunner.de, alex@shazbot.org, clg@redhat.com, stable@vger.kernel.org, mjrosato@linux.ibm.com, julianr@linux.ibm.com In-Reply-To: <20260122194437.1903-4-alifm@linux.ibm.com> References: <20260122194437.1903-1-alifm@linux.ibm.com> <20260122194437.1903-4-alifm@linux.ibm.com> Autocrypt: addr=schnelle@linux.ibm.com; prefer-encrypt=mutual; keydata=mQINBGHm3M8BEAC+MIQkfoPIAKdjjk84OSQ8erd2OICj98+GdhMQpIjHXn/RJdCZLa58k /ay5x0xIHkWzx1JJOm4Lki7WEzRbYDexQEJP0xUia0U+4Yg7PJL4Dg/W4Ho28dRBROoJjgJSLSHwc 3/1pjpNlSaX/qg3ZM8+/EiSGc7uEPklLYu3gRGxcWV/944HdUyLcnjrZwCn2+gg9ncVJjsimS0ro/ 2wU2RPE4ju6NMBn5Go26sAj1owdYQQv9t0d71CmZS9Bh+2+cLjC7HvyTHKFxVGOznUL+j1a45VrVS XQ+nhTVjvgvXR84z10bOvLiwxJZ/00pwNi7uCdSYnZFLQ4S/JGMs4lhOiCGJhJ/9FR7JVw/1t1G9a UlqVp23AXwzbcoV2fxyE/CsVpHcyOWGDahGLcH7QeitN6cjltf9ymw2spBzpRnfFn80nVxgSYVG1d w75ksBAuQ/3e+oTQk4GAa2ShoNVsvR9GYn7rnsDN5pVILDhdPO3J2PGIXa5ipQnvwb3EHvPXyzakY tK50fBUPKk3XnkRwRYEbbPEB7YT+ccF/HioCryqDPWUivXF8qf6Jw5T1mhwukUV1i+QyJzJxGPh19 /N2/GK7/yS5wrt0Lwxzevc5g+jX8RyjzywOZGHTVu9KIQiG8Pqx33UxZvykjaqTMjo7kaAdGEkrHZ dVHqoPZwhCsgQARAQABtChOaWtsYXMgU2NobmVsbGUgPHNjaG5lbGxlQGxpbnV4LmlibS5jb20+iQ JXBBMBCABBAhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAhkBFiEEnbAAstJ1IDCl9y3cr+Q/Fej CYJAFAmesutgFCQenEYkACgkQr+Q/FejCYJDIzA//W5h3t+anRaztihE8ID1c6ifS7lNUtXr0wEKx Qm6EpDQKqFNP+n3R4A5w4gFqKv2JpYQ6UJAAlaXIRTeT/9XdqxQlHlA20QWI7yrJmoYaF74ZI9s/C 8aAxEzQZ64NjHrmrZ/N9q8JCTlyhk5ZEV1Py12I2UH7moLFgBFZsPlPWAjK2NO/ns5UJREAJ04pR9 XQFSBm55gsqkPp028cdoFUD+IajGtW7jMIsx/AZfYMZAd30LfmSIpaPAi9EzgxWz5habO1ZM2++9e W6tSJ7KHO0ZkWkwLKicrqpPvA928eNPxYtjkLB2XipdVltw5ydH9SLq0Oftsc4+wDR8TqhmaUi8qD Fa2I/0NGwIF8hjwSZXtgJQqOTdQA5/6voIPheQIi0NBfUr0MwboUIVZp7Nm3w0QF9SSyTISrYJH6X qLp17NwnGQ9KJSlDYCMCBJ+JGVmlcMqzosnLli6JszAcRmZ1+sd/f/k47Fxy1i6o14z9Aexhq/UgI 5InZ4NUYhf5pWflV41KNupkS281NhBEpChoukw25iZk0AsrukpJ74x69MJQQO+/7PpMXFkt0Pexds XQrtsXYxLDQk8mgjlgsvWl0xlk7k7rddN1+O/alcv0yBOdvlruirtnxDhbjBqYNl8PCbfVwJZnyQ4 SAX2S9XiGeNtWfZ5s2qGReyAcd2nBna0KU5pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNjaG5lbGxlQ GlibS5jb20+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAAstJ1IDCl9y 3cr+Q/FejCYJAFAmesuuEFCQenEYkACgkQr+Q/FejCYJCosA/9GCtbN8lLQkW71n/CHR58BAA5ct1 KRYiZNPnNNAiAzjvSb0ezuRVt9H0bk/tnj6pPj0zdyU2bUj9Ok3lgocWhsF2WieWbG4dox5/L1K28 qRf3p+vdPfu7fKkA1yLE5GXffYG3OJnqR7OZmxTnoutj81u/tXO95JBuCSJn5oc5xMQvUUFzLQSbh prIWxcnzQa8AHJ+7nAbSiIft/+64EyEhFqncksmzI5jiJ5edABiriV7bcNkK2d8KviUPWKQzVlQ3p LjRJcJJHUAFzsZlrsgsXyZLztAM7HpIA44yo+AVVmcOlmgPMUy+A9n+0GTAf9W3y36JYjTS+ZcfHU KP+y1TRGRzPrFgDKWXtsl1N7sR4tRXrEuNhbsCJJMvcFgHsfni/f4pilabXO1c5Pf8fiXndCz04V8 ngKuz0aG4EdLQGwZ2MFnZdyf3QbG3vjvx7XDlrdzH0wUgExhd2fHQ2EegnNS4gNHjq82uLPU0hfcr obuI1D74nV0BPDtr7PKd2ryb3JgjUHKRKwok6IvlF2ZHMMXDxYoEvWlDpM1Y7g81NcKoY0BQ3ClXi a7vCaqAAuyD0zeFVGcWkfvxYKGqpj8qaI/mA8G5iRMTWUUUROy7rKJp/y2ioINrCul4NUJUujfx4k 7wFU11/YNAzRhQG4MwoO5e+VY66XnAd+XPyBIlvy0K05pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNj aG5lbGxlQGdtYWlsLmNvbT6JAlQEEwEIAD4CGwEFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AWIQSds ACy0nUgMKX3Ldyv5D8V6MJgkAUCZ6y64QUJB6cRiQAKCRCv5D8V6MJgkEr/D/9iaYSYYwlmTJELv+ +EjsIxXtneKYpjXEgNnPwpKEXNIpuU/9dcVDcJ10MfvWBPi3sFbIzO9ETIRyZSgrjQxCGSIhlbom4 D8jVzTA698tl9id0FJKAi6T0AnBF7CxyqofPUzAEMSj9ynEJI/Qu8pHWkVp97FdJcbsho6HNMthBl +Qgj9l7/Gm1UW3ZPvGYgU75uB/mkaYtEv0vYrSZ+7fC2Sr/O5SM2SrNk+uInnkMBahVzCHcoAI+6O Enbag+hHIeFbqVuUJquziiB/J4Z2yT/3Ps/xrWAvDvDgdAEr7Kn697LLMRWBhGbdsxdHZ4ReAhc8M 8DOcSWX7UwjzUYq7pFFil1KPhIkHctpHj2Wvdnt+u1F9fN4e3C6lckUGfTVd7faZ2uDoCCkJAgpWR 10V1Q1Cgl09VVaoi6LcGFPnLZfmPrGYiDhM4gyDDQJvTmkB+eMEH8u8V1X30nCFP2dVvOpevmV5Uk onTsTwIuiAkoTNW4+lRCFfJskuTOQqz1F8xVae8KaLrUt2524anQ9x0fauJkl3XdsVcNt2wYTAQ/V nKUNgSuQozzfXLf+cOEbV+FBso/1qtXNdmAuHe76ptwjEfBhfg8L+9gMUthoCR94V0y2+GEzR5nlD 5kfu8ivV/gZvij+Xq3KijIxnOF6pd0QzliKadaFNgGw4FoUeZo0rQhTmlrbGFzIFNjaG5lbGxlIDx uaWtzQGtlcm5lbC5vcmc+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAA stJ1IDCl9y3cr+Q/FejCYJAFAmesuuEFCQenEYkACgkQr+Q/FejCYJC6yxAAiQQ5NAbWYKpkxxjP/ AajXheMUW8EtK7EMJEKxyemj40laEs0wz9owu8ZDfQl4SPqjjtcRzUW6vE6JvfEiyCLd8gUFXIDMS l2hzuNot3sEMlER9kyVIvemtV9r8Sw1NHvvCjxOMReBmrtg9ooeboFL6rUqbXHW+yb4GK+1z7dy+Q 9DMlkOmwHFDzqvsP7eGJN0xD8MGJmf0L5LkR9LBc+jR78L+2ZpKA6P4jL53rL8zO2mtNQkoUO+4J6 0YTknHtZrqX3SitKEmXE2Is0Efz8JaDRW41M43cE9b+VJnNXYCKFzjiqt/rnqrhLIYuoWCNzSJ49W vt4hxfqh/v2OUcQCIzuzcvHvASmt049ZyGmLvEz/+7vF/Y2080nOuzE2lcxXF1Qr0gAuI+wGoN4gG lSQz9pBrxISX9jQyt3ztXHmH7EHr1B5oPus3l/zkc2Ajf5bQ0SE7XMlo7Pl0Xa1mi6BX6I98CuvPK SA1sQPmo+1dQYCWmdQ+OIovHP9Nx8NP1RB2eELP5MoEW9eBXoiVQTsS6g6OD3rH7xIRxRmuu42Z5e 0EtzF51BjzRPWrKSq/mXIbl5nVW/wD+nJ7U7elW9BoJQVky03G0DhEF6fMJs08DGG3XoKw/CpGtMe 2V1z/FRotP5Fkf5VD3IQGtkxSnO/awtxjlhytigylgrZ4wDpSE= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 26 Jan 2026 22:00:10 +0100 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Z4vh3XRA c=1 sm=1 tr=0 ts=6977d61c cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=-MkQjPFO3SNDZXfgKHQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: xTs245tnLTeBEu32oeOo8jf1ozmB_d4u X-Proofpoint-ORIG-GUID: xTs245tnLTeBEu32oeOo8jf1ozmB_d4u X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTI2MDE3OCBTYWx0ZWRfX1I2NPJeIsovg XOXNW/wflxSsZF5N3jZgH3hvTJm8ddzTILa0MqKAAExO2Ewgdw4DINsyr+Tio6toKlb+YVBtGwd 4Qaf/Qs+IQgRomrLurBBVpp1iYysXVIoC3u/94E087mo52Ri4XODhN0XJdM8MCErT885w9V1X05 1XkmJoTA+vTwUJ3LjtWwWePZKc3sR49vjvasVm+2/4BVPWJCOHiZYBcQffsqujBt08Wa0t2mtXq 8HkEOmznfsuDuYGcFe89z+HDJ4aL8D7D0f3x8XbQjPV9VhkSFkrfa4XF/aFtBfHQI/SBc2jMsUD 02eIiH7RVXIbfOfBsCDruGOZ6lBD3b2h16Kg9he4XfxGvZ0jhRZ1Ps/ohLG1mU3mKbnOeIvxrpD hNu0VwKVwmyg/y3myDm8Y4srCH4Vpxdqq0H+s272+kWFRmGC8WeAxNiEADifufsDnhSG1lkRK37 qhcTPNzIenR7RcelVpA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.20,FMLib:17.12.100.49 definitions=2026-01-26_04,2026-01-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 phishscore=0 priorityscore=1501 bulkscore=0 adultscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601260178 On Thu, 2026-01-22 at 11:44 -0800, Farhan Ali wrote: > The current reset process saves the device's config space state before > reset and restores it afterward. However errors may occur unexpectedly an= d > it may then be impossible to save config space because the device may be > inaccessible (e.g. DPC) or config space may be corrupted. This results in > saving corrupted values that get written back to the device during state > restoration. >=20 > With a reset we want to recover/restore the device into a functional stat= e. > So avoid saving the state of the config space when the device config spac= e > is inaccessible. >=20 > Signed-off-by: Farhan Ali > --- > drivers/pci/pci.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) >=20 > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index c105e285cff8..e7beaf1f65a7 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4960,6 +4960,7 @@ EXPORT_SYMBOL_GPL(pci_dev_unlock); > =20 > static void pci_dev_save_and_disable(struct pci_dev *dev) > { > + u32 val; Nit: I believe the PCI subsystem prefers reverse X-mas tree declarations > const struct pci_error_handlers *err_handler =3D > dev->driver ? dev->driver->err_handler : NULL; > =20 > @@ -4980,6 +4981,19 @@ static void pci_dev_save_and_disable(struct pci_de= v *dev) > */ > pci_set_power_state(dev, PCI_D0); > =20 > + /* > + * If device's config space is inaccessible it can return ~0 for > + * any reads. Since VFs can also return ~0 for Device and Vendor ID > + * check Command and Status registers. At the very least we should > + * avoid restoring config space for device with error bits set in > + * Status register. > + */ > + pci_read_config_dword(dev, PCI_COMMAND, &val); > + if (PCI_POSSIBLE_ERROR(val)) { > + pci_warn(dev, "Device config space inaccessible\n"); > + return; > + } > + > pci_save_state(dev); > /* > * Disable the device by clearing the Command register, except for Looks good to me thanks! Feel free to add: Reviewed-by: Niklas Schnelle