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Fri, 29 Aug 2025 08:38:11 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8013958056; Fri, 29 Aug 2025 08:38:11 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 65B1158052; Fri, 29 Aug 2025 08:38:09 +0000 (GMT) Received: from [9.111.24.125] (unknown [9.111.24.125]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Fri, 29 Aug 2025 08:38:09 +0000 (GMT) Message-ID: Subject: Re: [PATCH 3/4] PCI/ERR: Amend documentation with DPC and AER specifics From: Niklas Schnelle To: Lukas Wunner , Bjorn Helgaas , Jonathan Corbet Cc: Terry Bowman , Ilpo Jarvinen , Sathyanarayanan Kuppuswamy , Linas Vepstas , Mahesh J Salgaonkar , Oliver OHalloran , linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org, Brian Norris Date: Fri, 29 Aug 2025 10:38:08 +0200 In-Reply-To: <42726e2fd197959d6228d25552504353ffb53545.1756451884.git.lukas@wunner.de> References: <42726e2fd197959d6228d25552504353ffb53545.1756451884.git.lukas@wunner.de> Autocrypt: addr=schnelle@linux.ibm.com; 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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAyMSBTYWx0ZWRfX2mfC+/5JgXSm tvXfxo0aw0TeGMtdRcZgeaFj7bbtYMM8AnlgJKcNdvfG7m4eds11aZWQrAv+du2NMr4KdTZd/gL SMGC+2fer/EUZ7vuwkIHU/x3EPuat9hbZzIkr7WeZ9wg2SENkqLS0kDdKLFCWyCtePLCJpNGEpy K2oxw9JkZ36uoCnlnRwnt8rJUTBWlYgqNd81vmr7rnzNjoaw72APK0FDcmT/ArqD+G4Adt5yubq jMD9OjkVSHEqYEjGJds3iSbPNNFWmpTRBcvxwbpUtPdY+6Vx3gC3G7U6WN9SPn8YZXI/IkLzu7u VCkmG2Qi6m3Pgblk54FGJkbm8toBEZcYzf9D+N1DogCuG3fsvh8dGTkJxzMzzVtAOn1VVvsggQ4 FFknujpQ X-Proofpoint-ORIG-GUID: BBnMbQ55CD2lrHR8MPX4YkQVGPcy3I2g X-Proofpoint-GUID: WBzPLu_GpKVU_nK-p2KzqhCxmIi19MC8 X-Authority-Analysis: v=2.4 cv=Ndbm13D4 c=1 sm=1 tr=0 ts=68b166f5 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=KkUFHGsvljIy0fMCjwwA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-29_02,2025-08-28_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 clxscore=1011 phishscore=0 malwarescore=0 suspectscore=0 bulkscore=0 spamscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508230021 On Fri, 2025-08-29 at 09:25 +0200, Lukas Wunner wrote: > Amend the documentation on PCI error recovery with specifics about > Downstream Port Containment and Advanced Error Reporting: >=20 > * Explain that with DPC, devices are inaccessible upon an error (similar > to EEH on powerpc) and do not become accessible until the link is > re-enabled. >=20 > * Explain that with AER, although devices may already be accessible in th= e > ->error_detected() callback, accesses should be deferred to the > ->mmio_enabled() callback for compatibility with EEH on powerpc. >=20 > Signed-off-by: Lukas Wunner > --- > Documentation/PCI/pci-error-recovery.rst | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) >=20 > diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI= /pci-error-recovery.rst > index d5c661baa87f..c88c304b2103 100644 > --- a/Documentation/PCI/pci-error-recovery.rst > +++ b/Documentation/PCI/pci-error-recovery.rst > @@ -122,6 +122,10 @@ A PCI bus error is detected by the PCI hardware. On= powerpc, the slot > is isolated, in that all I/O is blocked: all reads return 0xffffffff, > all writes are ignored. > =20 > +Similarly, on platforms supporting Downstream Port Containment > +(PCIe r7.0 sec 6.2.11), the link to the sub-hierarchy with the > +faulting device is disabled. Any device in the sub-hierarchy > +becomes inaccessible. > =20 > STEP 1: Notification > -------------------- > @@ -204,6 +208,23 @@ link reset was performed by the HW. If the platform = can't just re-enable IOs > without a slot reset or a link reset, it will not call this callback, an= d > instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot R= eset) > =20 > +.. note:: > + > + On platforms supporting Advanced Error Reporting (PCIe r7.0 sec 6.2), > + the faulting device may already be accessible in STEP 1 (Notification= ). > + Drivers should nevertheless defer accesses to STEP 2 (MMIO Enabled) > + to be compatible with EEH on powerpc. I'm biased of course but I'd prefer either "with error recovery support on powerpc and s390" or simply "with systems where devices are inaccessible until MMIO is re-enabled explicitly or a reset occurs.".