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Tue, 23 Jun 2026 11:29:37 +0000 (GMT) Received: from [9.224.91.56] (unknown [9.224.91.56]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Tue, 23 Jun 2026 11:29:37 +0000 (GMT) Message-ID: <087b5cafd04d2fee89f3a4a941d425e967d1ee72.camel@linux.ibm.com> Subject: Re: [PATCH v20 4/4] PCI/MSI: Enable memory decoding before restoring MSI-X messages From: Niklas Schnelle To: Farhan Ali , Thomas Gleixner , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Cc: helgaas@kernel.org, alex@shazbot.org, mjrosato@linux.ibm.com In-Reply-To: References: <20260622171840.1618-1-alifm@linux.ibm.com> <20260622171840.1618-5-alifm@linux.ibm.com> <87ik7al3of.ffs@fw13> 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 CYJAFAmmAWs8FCQl6sYAACgkQr+Q/FejCYJAn2g//UKzlXOgizdk0wudLooRbGzDo23ktGSPK5Oj9 9o5z6v4Jz5+qOHo5835683cqkMLM9//udA1ZcKV88LVwyfmoHChPW24cWBmOEy7RJOWCR4WeEINaO pZUGF5YOx7oKTkPs511ky2FR0Heg35754pgTuTMEpYzRXr5pNMPS8mHXcXSARFPDPaCF+uBJ9BafO L7XbpSwKRttePsWAlPHbSbloeDApBfHUhcF/pbuM9GNs+c/8V9NK+SwwqNK214t7jaSq9k+19/hfE jvU45nbiYQM4VqGCelxVFRWol93JnwPFp/JaMgxgV1VYFH9Ijtgh+qNVVBqO8bbTjioFKy1bHdprN 9GyPLDxoaI/lBg+5CwKewzazUjFd0xaqZbTXSgNK4ev/IuNI3qZV8tpvZZWwIgZU1K0Bhplt8Sku+ O9Yl2H54erq9zuzwXjqBJtoW0+MaKbe+1gZ/v2/AVE2VeQMugPUWDg+2bpJaApRkeA4xQ9XfeW6Bp It7xYrwwbVhQtWRC0sRh+QNlU9HI28wPSnLWn7HFBeWupaIrxSp4IEL3eHUn8xv4aA8lpdNsHXD/X vqOSUwy5jlTPTlemvwaC9mNHagNdVXng8C6+hxiDLhZ6xH2P4qNHTKmjW61NsdF6Y/HfWP+lmbi8/ 474UNCltDt/fP01ajqogfWZKFymoH0O0KU5pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNjaG5lbGxlQ GlibS5jb20+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAAstJ1IDCl9y 3cr+Q/FejCYJAFAmmAWusFCQl6sYAACgkQr+Q/FejCYJAtIw//WmQW/Z+SLdfrlDH5J2bvixzFNnO TOvp8uM8vcNZsxZwPXem4AeCXHayCqipxpa0iXWufEIvdMxkBxWvvM//V+rTUgQnJe6nhDxfLGklx 5Mb2H+K/ndS73ElCuA30MPYq7mHr8i3gEmi2ZFX1W47JecJ8hno/DQxhHRG7bd+GFsiKCbsjLWXNq s/VaAK9uyOTQx7m6/2nR8L+Mvl1BrRXwkj7Qp0qxfQSd4r+IVNBzNFOcrGagBqsyHrN7Is7IICktH 9VFl/G8P+hfviHQLnlxw9ltzpM1Dy6N1+BM3kbqD59gX+L6wqiLJI42eh+SHCiy35FvD3AFlYx4jZ MWE6qIgFnbwcL1kvcA7nnwfr3ZizCYPm8e334xXxslXBoRGsvjXSbAeAyZo2dvJXffNHdcDdUbJSl CfOixNGGKiQvs00X9ekfq9WmmRFvmYHu/m3lg1OXnMjFFIO41O51ZdhbEYJiqZEki7jA8Hd9xuWwQ nFDHhacU3xxivZ4BKQGQc+4XZ3yp/q6+7ux9prepRy/LeRyoaAmE67oxEsAgj+qyA3Tfy5nRTDdRQ E//gpaIt9H1VEx+68dRWHroxBQeozpnFPi25AlX3k4/EtVZjcItPWgE9iru1qT4DH3BBrz7Kd1zUw NnQC77zDJyZD2WUj1E+5bftO0aeE+7HZXj3tM/ea0K05pa2xhcyBTY2huZWxsZSA8bmlrbGFzLnNj aG5lbGxlQGdtYWlsLmNvbT6JAlQEEwEIAD4CGwEFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AWIQSds ACy0nUgMKX3Ldyv5D8V6MJgkAUCaYBa6wUJCXqxgAAKCRCv5D8V6MJgkF/TEACOY2kL4NGFIbWeM5 TUhatxqe8c3RT6jvNjq32CkvaK/cSZzBkS0smddyOzxt2WnsvMgkr9cM7P+CevoMwhT3e0lgQbqBD /vXZJjWKddC+iKXeqWkjMVcgCOsWNZ7PWEzRUT5X1AEFq2zzxQAQ/bCWEYNqIbHN4b6G1Wk+2Y598 +KypZ3FS0bwiItnPQOWzOOqJCGxDxaEUuXFx4ah8HtVdtIev8jPS/5uzQO9iG2vZQUWeMEYZtfMHW sbFWqo2A3lxB+KPzNIYFhul4Lyx1CwvKUAGSHOx7FZuc2xI5DYt/Wdh2QyKFYr7xVzv3uwJjeS1+3 6gvyB7DJaQuY+PziNPv4GPr5wy0cRkJ6Ps15fgC6y6wNwoNdNXKlwiuclIsBzJKa7A0pZMIfpCpIJ bEHP7oy3drBRAhIrBx7Lx1lyqqodDqc+ok5IQ5WcKG/TOrH732mTmJX6fxYTiCVxcU4WLJSNZbrZ/ pjF0AWXs7E+onAkQy6RLg/XU1iiU5QdMvug+fTA6TpPSUMdujWtGWUt3/4nC+69AVc8tXtRQTZ7gP t7uIcQFwPqUuJGS26vl0w/6dIABQAyU9acvE3adCZra+/PBKFZi/yxT1WgV1T2mexKSWwQgLcR57J Yp5oWnQRgi/S6fAoskIWkp9UVcfAQPY0p45NwO5cZR9/g06JZmyrQhTmlrbGFzIFNjaG5lbGxlIDx uaWtzQGtlcm5lbC5vcmc+iQJUBBMBCAA+AhsBBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAFiEEnbAA stJ1IDCl9y3cr+Q/FejCYJAFAmmAWusFCQl6sYAACgkQr+Q/FejCYJAz4A/9F+dMhzu7YonagL4qh WDz5IpRD4vzYKOBZ+qwYp1ugJz1BIUppN9i68HKoS4ARfgP97Sv9GpOy9g7L0lymH2MPF8hRPK0Yn 7DKIkeu/r28YWEoWfoVm5reC+gpxMgmxBz4JScE4f6xfa7+Nw0bbTDl+nxftJD7lf/dTiruNJsXph HQnZ5wPXmxeH6XVJikfpyrGe8iJZALbtHtjlx6Omu7NvRGikenB8trrWS5W0F60ZdbqH1HdmDDcrZ pDq6LtAARHK5tGRm0SK6sZpKe3nULFeeCt7T/edk2FC6KVh4sL1jw1kyceX4DjiMffqYBPrhK5gz5 cDIixLBF9C6Wt1ObvuDBrIQf1/3q6EZrUrUuf6qtaXDMuC6cSlShm47qaPEvVYh67O9JZQ7vzvaea UI74DJUb8Pjnz7mTOmMOzsS1gUhCue4n2YSSM6ythioCGb/3bgMGTpuer3JhvZG5s5uKD9yyj8s8x 35qJkCFfjmjVx9s3vSUS48X+cUpYcMispErKzFu7C0YgKoxvJ4XTfXlDBiMFMPYcN67hsb2jeYHVJ wzE+fIZiDx9JLh1oQW2krwjweisE+3glOaKXZKi0fBtkxyH41iemLtLNYZRJopv6ykdl3hiI+Nh+a 3FZJPTo/OpqchMm8XIeDxC4NFFiPMpyLeYzIxO7eZpiGrAjVTE= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Tue, 23 Jun 2026 13:28:35 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNjIzMDA5MiBTYWx0ZWRfX6skRVgKw1nMR Ay8kxSPO9BWQJNrGy71NHeW1M78cF41AFHfVOHFZT2Uwmu3hsE4sBlLkltHOAYeM09OvmFGL/L6 piIwJkaYyRrs1DQSsCeYIHbKA7cbTck= X-Proofpoint-ORIG-GUID: GaE5wnh-g8ix_yYuFWP8qsowCLm6vBX1 X-Authority-Analysis: v=2.4 cv=Oph/DS/t c=1 sm=1 tr=0 ts=6a3a6e25 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=cv3ftqYjHt7s5IYWvSEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjIzMDA5MiBTYWx0ZWRfX6T8aF2B3Ft8K ExOtJaq/Ebhpg2om1V9+1Y8I8s0iT4Hn9EJXf57WUBgv11b3Kp2KAQzZSYRzD5fJGCxX1ACpTKZ 17FWoeD6JRwJ8jqcWCbKmjJrS/o6brItCenyBVr84zv1RCaT0Et3rwzaMwGbJg/K9H4MK2zInDy aDRp4BDv5FVF+sLJpWLC+mtP3LG3h58MwapVjoBL5Rb77dKuP0vd+2+XWQLraeqXYQsXLo39c1/ ujBHheHbK+RKGxVxEi07cwJ/uQaD62lTo/uEa4y646pjtNcmqNujFiNnjVc8Wzloe2YAp2k9C6W lytjd/jqw9fJaAJN+i54W3h3CCXMNn2guYDBYpmJ8SKMeu4xXhs3DCAZXlNdEdT6Ai+e4llSLbE CrMRVcdJh6acrSpCr2g9ZENGV0y4XbZfYXdaWQR0ncXFJ9gB+zwD9AkULap6RAFhXwuaieGDds4 vDegiSTvdLk2A4lmhGA== X-Proofpoint-GUID: GaE5wnh-g8ix_yYuFWP8qsowCLm6vBX1 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-23_02,2026-06-23_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 priorityscore=1501 clxscore=1011 impostorscore=0 malwarescore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606230092 On Mon, 2026-06-22 at 13:49 -0700, Farhan Ali wrote: > On 6/22/2026 1:29 PM, Thomas Gleixner wrote: > > On Mon, Jun 22 2026 at 10:18, Farhan Ali wrote: > > > The current MSI-X restoration path assumes the Command register Memor= y bit > > > is enabled when writing MSI-X messages. But its possible the last sav= ed and > > > restored state of device may not have the Memory bit enabled, even if= a > > > device driver later enables Memory bit and MSI-X. Attempting to acces= s > > > Memory space without Memory bit enabled can lead to Unsupported Reque= st > > > (UR) from the device. Fix this by enabling Memory bit and restore > > > it afterwards. > > >=20 > > > Signed-off-by: Farhan Ali > > > --- > > >=20 --- 8< --- > > > @@ -882,6 +883,8 @@ void __pci_restore_msix_state(struct pci_dev *dev= ) > > > pci_intx_for_msi(dev, 0); > > > pci_msix_clear_and_set_ctrl(dev, 0, > > > PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL); > > > + pci_read_config_word(dev, PCI_COMMAND, &cmd); > > > + pci_write_config_word(dev, PCI_COMMAND, cmd | PCI_COMMAND_MEMORY); > > Can we please have a comment there which explains this? Three month dow= n > > the road this will results in head scratching otherwise. > >=20 > > I agree with Niklas that this wants a Fixes and a Cc:stable tag. > >=20 > > Other than that: > >=20 > > Reviewed-by: Thomas Gleixner > >=20 > > Thanks, > >=20 > > tglx > >=20 > I can add a comment, how about something like below? >=20 > "The restored device state may not have Memory decoding enabled in=20 > Command register. Since the MSI-X was enabled for the device, enable=20 > Memory decoding before restoring MSI-X" Missing "the" before "Command register" other than that this sounds good to me and I agree with Thomas that a comment makes sense here. >=20 > For the Fixes tag, do you have a suggestion for a commit? This behavior= =20 > has been present since=C2=A041017f0cac92 ("[PATCH] PCI: MSI(X) save/resto= re=20 > for suspend/resume" which introduced these restore functions. So should= =20 > be Fixes against 41017f0cac92? I'm not sure but my guess would be that for suspend/resume this isn't an issue since the suspend part would save the state with Memory Space enabled. So it wouldn't be broken in this original use-case. I think the problem only occurs in case restore is done for error recovery. Might it make sense to have the Fixes tag point to a2f1e22390ac ("PCI/ERR: Ensure error recoverability at all times") even though that only helps to expose the issue? Thanks, Niklas