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Thu, 25 Jun 2026 21:52:45 +0000 (GMT) Received: from [9.61.243.248] (unknown [9.61.243.248]) by smtpav06.wdc07v.mail.ibm.com (Postfix) with ESMTP; Thu, 25 Jun 2026 21:52:45 +0000 (GMT) Message-ID: Date: Thu, 25 Jun 2026 14:52:45 -0700 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 v19 2/3] vfio-pci/zdev: Add a device feature for error information To: Alex Williamson Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, helgaas@kernel.org, schnelle@linux.ibm.com, mjrosato@linux.ibm.com References: <20260615183616.2902-1-alifm@linux.ibm.com> <20260615183616.2902-3-alifm@linux.ibm.com> <20260623150744.08177808@shazbot.org> Content-Language: en-US From: Farhan Ali In-Reply-To: <20260623150744.08177808@shazbot.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ty_5ZYeePwrmLwYX-vcIZLqt085HhemP X-Proofpoint-GUID: ty_5ZYeePwrmLwYX-vcIZLqt085HhemP X-Authority-Analysis: v=2.4 cv=Y4XIdBeN c=1 sm=1 tr=0 ts=6a3da330 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=y--LQT-nAaOemKz3C48A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjI1MDE4OCBTYWx0ZWRfX6O6LteddjY+J ODvjp406azaxAKbWGhnhtOTOj7zunZ8hZEDb4mID8EfiLuDUryFf4Uk/VW1KHmtsLCeXaJHUF+a KNIsQFjjCiW/S3oZP7FP4o8aZ8ad382lGykj08q4aP4Uf2AwAixxaRtTVh2PXNAeqUegPosEocB bQWR31gpVrRl4wpjB5LTsJ2ayFuRAM0C9mXmDg/tZAX+XZFOkZJvM1CX8tP3TziBc3SSwvdNpeR uvhuJwj0hjv+00egyOrfaW8/dN1F+46ySOqHG11BmQnUkOBBHctHcDsO0SPQWe/h9nU8QSsSSFe y3k4Ew3UegnbN5FskoA4yit9NSdqRY7xJ7nV7X6kQtIHIsEZbYQQ0IfXsDna2tMiIXQG6Kv9iOW ocsqyv/HSavKLDzAbjpVdtu6DegalNZ3B1ML8sfqZ1Bk1/uHhcPKdo1Xfbtm4Q4hDn2bceTv+cn fuEOToDy4GnrdkRIBeg== X-Proofpoint-Spam-Info: AW1haW4tMjYwNjI1MDE4OCBTYWx0ZWRfXwqZLXDMkiLqc yY3/PGy1U7YCIw105rTD7IIfXGJvx2bGhEa3JJAJJOchc98sMO62NhwbAPCVHYyLlGB5KFTNt/B cCE/lthD2/GOQV+szJrry7X8j7pnI0M= 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=2026-06-25_02,2026-06-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 spamscore=0 clxscore=1015 suspectscore=0 impostorscore=0 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606250188 On 6/23/2026 2:07 PM, Alex Williamson wrote: > On Mon, 15 Jun 2026 11:36:15 -0700 > Farhan Ali wrote: > >> For zPCI devices, we have platform specific error information. The platform >> firmware provides this error information to the operating system in an >> architecture specific mechanism. To enable recovery from userspace for >> these devices, we want to expose this error information to userspace. Add a >> new device feature to expose this information. >> >> Reviewed-by: Matthew Rosato >> Reviewed-by: Niklas Schnelle >> Signed-off-by: Farhan Ali >> --- >> arch/s390/include/asm/pci.h | 2 ++ >> arch/s390/pci/pci_event.c | 19 ++++++++++++++ >> drivers/vfio/pci/vfio_pci_core.c | 2 ++ >> drivers/vfio/pci/vfio_pci_priv.h | 9 +++++++ >> drivers/vfio/pci/vfio_pci_zdev.c | 43 ++++++++++++++++++++++++++++++++ >> include/uapi/linux/vfio.h | 30 ++++++++++++++++++++++ >> 6 files changed, 105 insertions(+) >> >> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h >> index 016386f7ef4a..88a125b92bdd 100644 >> --- a/arch/s390/include/asm/pci.h >> +++ b/arch/s390/include/asm/pci.h >> @@ -364,6 +364,8 @@ int zpci_clear_error_state(struct zpci_dev *zdev); >> int zpci_reset_load_store_blocked(struct zpci_dev *zdev); >> void zpci_start_mediated_recovery(struct zpci_dev *zdev); >> void zpci_stop_mediated_recovery(struct zpci_dev *zdev); >> +int zpci_get_pending_error(struct zpci_dev *zdev, >> + struct zpci_ccdf_err *ccdf); >> >> #ifdef CONFIG_NUMA >> >> diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c >> index 8934b640a095..3ad16038e005 100644 >> --- a/arch/s390/pci/pci_event.c >> +++ b/arch/s390/pci/pci_event.c >> @@ -77,6 +77,25 @@ static int zpci_store_pci_error(struct pci_dev *pdev, >> return 0; >> } >> >> +int zpci_get_pending_error(struct zpci_dev *zdev, >> + struct zpci_ccdf_err *ccdf) >> +{ >> + int head = 0; >> + >> + guard(mutex)(&zdev->pending_errs_lock); >> + >> + if (!zdev->pending_errs.count) >> + return -ENOMSG; >> + >> + head = zdev->pending_errs.head % ZPCI_ERR_PENDING_MAX; >> + memcpy(ccdf, &zdev->pending_errs.err[head], >> + sizeof(struct zpci_ccdf_err)); >> + zdev->pending_errs.head++; >> + zdev->pending_errs.count--; >> + return 0; >> +} >> +EXPORT_SYMBOL_GPL(zpci_get_pending_error); >> + >> void zpci_start_mediated_recovery(struct zpci_dev *zdev) >> { >> guard(mutex)(&zdev->pending_errs_lock); >> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c >> index 050e7542952e..27642f10fe97 100644 >> --- a/drivers/vfio/pci/vfio_pci_core.c >> +++ b/drivers/vfio/pci/vfio_pci_core.c >> @@ -1569,6 +1569,8 @@ int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags, >> return vfio_pci_core_feature_token(vdev, flags, arg, argsz); >> case VFIO_DEVICE_FEATURE_DMA_BUF: >> return vfio_pci_core_feature_dma_buf(vdev, flags, arg, argsz); >> + case VFIO_DEVICE_FEATURE_ZPCI_ERROR: >> + return vfio_pci_zdev_feature_err(device, flags, arg, argsz); >> default: >> return -ENOTTY; >> } >> diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h >> index fca9d0dfac90..4e7162234a2e 100644 >> --- a/drivers/vfio/pci/vfio_pci_priv.h >> +++ b/drivers/vfio/pci/vfio_pci_priv.h >> @@ -93,6 +93,8 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev, >> struct vfio_info_cap *caps); >> int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev); >> void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev); >> +int vfio_pci_zdev_feature_err(struct vfio_device *device, u32 flags, >> + void __user *arg, size_t argsz); >> #else >> static inline int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev, >> struct vfio_info_cap *caps) >> @@ -107,6 +109,13 @@ static inline int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev) >> >> static inline void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev) >> {} >> + >> +static inline int vfio_pci_zdev_feature_err(struct vfio_device *device, >> + u32 flags, void __user *arg, >> + size_t argsz) >> +{ >> + return -ENOTTY; >> +} >> #endif >> >> static inline bool vfio_pci_is_vga(struct pci_dev *pdev) >> diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c >> index 78a28db00c6d..c0d6362cc4eb 100644 >> --- a/drivers/vfio/pci/vfio_pci_zdev.c >> +++ b/drivers/vfio/pci/vfio_pci_zdev.c >> @@ -141,6 +141,49 @@ int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev, >> return ret; >> } >> >> +int vfio_pci_zdev_feature_err(struct vfio_device *device, u32 flags, >> + void __user *arg, size_t argsz) >> +{ >> + struct vfio_device_feature_zpci_err err = {}; >> + struct vfio_pci_core_device *vdev; >> + struct zpci_ccdf_err ccdf = {}; >> + struct zpci_dev *zdev; >> + int ret; >> + >> + vdev = container_of(device, struct vfio_pci_core_device, vdev); >> + zdev = to_zpci(vdev->pdev); >> + if (!zdev) >> + return -ENODEV; >> + >> + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET, >> + sizeof(err)); >> + if (ret != 1) >> + return ret; >> + >> + ret = zpci_get_pending_error(zdev, &ccdf); >> + if (ret) >> + return ret; >> + >> + err.fh = ccdf.fh; >> + err.fid = ccdf.fid; >> + err.ett = ccdf.ett; >> + err.mvn = ccdf.mvn; >> + err.dmaas = ccdf.dmaas; >> + err.q = ccdf.q; >> + err.rw = ccdf.rw; >> + err.faddr = ccdf.faddr; >> + err.pec = ccdf.pec; >> + >> + if (copy_to_user(arg, &err, sizeof(err))) { >> + dev_warn_ratelimited(device->dev, >> + "Failed to handle PCI error event for PCI function 0x%x", >> + zdev->fid); >> + return -EFAULT; >> + } >> + >> + return 0; >> +} >> + >> int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev) >> { >> struct zpci_dev *zdev = to_zpci(vdev->pdev); >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h >> index 5de618a3a5ee..83c93193b22d 100644 >> --- a/include/uapi/linux/vfio.h >> +++ b/include/uapi/linux/vfio.h >> @@ -1534,6 +1534,36 @@ struct vfio_device_feature_dma_buf { >> */ >> #define VFIO_DEVICE_FEATURE_MIG_PRECOPY_INFOv2 12 >> >> +/** >> + * VFIO_DEVICE_FEATURE_ZPCI_ERROR feature provides PCI error information to >> + * userspace for vfio-pci devices on s390. On s390, PCI error recovery >> + * involves platform firmware and notification to operating systems is done >> + * by architecture specific mechanism. Exposing this information to >> + * userspace allows it to take appropriate actions to handle an >> + * error on the device. The ioctl returns -ENOMSG if there are no pending >> + * PCI errors. >> + */ >> + >> +struct vfio_device_feature_zpci_err { >> + __u32 feature_flags; /* Indicate future features */ >> + __u32 reserved1; >> + __u32 fh; /* function handle */ >> + __u32 fid; /* function id */ >> + __u64 faddr; /* failing address */ >> + __u32 ett : 4; /* expected table type */ >> + __u32 mvn : 12; /* MSI vector number */ >> + __u32 dmaas : 8; /* DMA address space */ >> + __u32 reserved2 : 6; >> + __u32 q : 1; /* event qualifier */ >> + __u32 rw : 1; /* read/write */ >> + __u32 reserved3; >> + __u16 reserved4; >> + __u16 pec; /* PCI event code */ >> + __u8 reserved5[28]; /* Allow for future expansion */ >> +}; > In v18 I probed whether this should be passed as opaque data as we're > doing for FMB, which was declined because the user doesn't know the > size. However, the fmb_length is provided through a device info cap, > where we could extend the existing zpci info cap with a v3 that does > report this fixed size. That doesn't seem like an insurmountable > barrier. > > In the implementation here, we have the worst combination of > trade-offs, reserved fields for some vague notion of future expansion > and bitfields that mimic the architecture specification but don't fit > well into a uAPI as their position is compiler dependent. > > This should either fully abandon the architecture layout and create a > well defined, naturally aligned uAPI structure, or extend the zpci info > cap to report the size and pass the error data as opaque. I think it should be doable by extending the zpci info cap and providing a size for userspace to provide a buffer. I think making the error data opaque makes sense, and it provides a mechanism (along with size) to possibly extend the data returned to user. I will look into implementing that in the next version. Thanks Farhan > As Bjorn notes, we're already into the merge window, so this is at best > v7.3 material, and as we've designed the split, merging the vfio > changes will be dependent on a branch provided with the PCI changes. > Thanks, > > Alex