From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 27BCB35E949; Mon, 13 Apr 2026 23:40:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776123660; cv=none; b=R5/nVZdPa3KVXGNdmsao/BcMrYyBRnVW4aAo2xgkRVL1gvmCH6LYXoP3gMtKK7dcolXtZDbY5/Cq4Gl5cff5d5PUpVU0iQOawi6yWfWky08q0+6IDWemgM19YhglujW/n+6yQkyMfunTJPR3+aWTfFCKojaeRdc5vS9FvFDjmXU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776123660; c=relaxed/simple; bh=MAiEAcmw9bIasbQc42qB2Mu70OEKB/rRrgqlAtn/oPc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Z8nXebVaekMCEoPaJqtt7MMnb3Es2P+70r4VPwiZnaQg91FmFb6mTK4oM5QoijKMXvwL3WhEq+X8T4DkBXoFg1tLaRPOvFhw+i8jheXHnoorAjuF0pHxHq1AEWwKnDkXZpXd+JyOzhZ8U3VocZEV8fd4CmCdJcwD0qHEpOqWE08= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=YfOZuesJ; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="YfOZuesJ" Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 63DLIFHQ1804537; Mon, 13 Apr 2026 23:40:53 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=nRrPRH vAx0lYxy3y85QdUpSwvFTrFT9GLgDb39V+ryg=; b=YfOZuesJfiAsviHtCDEZsx dWQZfQ0Tk8ul5NS0i1HhKS5KgsvYmPhudJ4j/PiOk1FRZcALTknGcqOqfjDGOYf1 XZ1yQXGSLjRnlmr8Oji4pUkcil32m3fYhgUMC+oYH6RSdqHbwNqZn4GMPQr9ziiW pZgqgb9QzjFN/6TllmDk6SbNp2CDyCbkmkb/CFQPuFfzbSmsaZDfYJSmfIaSxfZI Xe0j8Bt5CMnkPC/rgfmZ4yj1Dbft88qey+t0vEovHzyBHu8n9qxA1yndGFxet2+a /vNSztpDpuVrgl/WnqmPDEQ9Q3YY4AhpVASgCu14MaEC8Q+zhASDg4QWHa8DqBCA == Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4dh89k0a80-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Apr 2026 23:40:53 +0000 (GMT) Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 63DM0IfU003514; Mon, 13 Apr 2026 23:40:52 GMT Received: from smtprelay07.wdc07v.mail.ibm.com ([172.16.1.74]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4dg1mn789c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Apr 2026 23:40:52 +0000 Received: from smtpav03.wdc07v.mail.ibm.com (smtpav03.wdc07v.mail.ibm.com [10.39.53.230]) by smtprelay07.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 63DNepcG26149574 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Apr 2026 23:40:51 GMT Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6769A5805C; Mon, 13 Apr 2026 23:40:51 +0000 (GMT) Received: from smtpav03.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4B92558054; Mon, 13 Apr 2026 23:40:50 +0000 (GMT) Received: from [9.61.242.98] (unknown [9.61.242.98]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 13 Apr 2026 23:40:50 +0000 (GMT) Message-ID: Date: Mon, 13 Apr 2026 16:40:49 -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 v13 5/7] 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, lukas@wunner.de, clg@redhat.com, kbusch@kernel.org, schnelle@linux.ibm.com, mjrosato@linux.ibm.com References: <20260413210608.2912-1-alifm@linux.ibm.com> <20260413210608.2912-6-alifm@linux.ibm.com> <20260413165758.0f87312b@shazbot.org> Content-Language: en-US From: Farhan Ali In-Reply-To: <20260413165758.0f87312b@shazbot.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: kB3pJ4wLEUyKh3m8mDOvvYKlW5_Xg91H X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDEzMDIyOSBTYWx0ZWRfX8BpfcXUdMbNr H20hG91+wZ67yZ2Y+JCdcJMrQMO8NymBcK7wDnlfCOm+TSpFRsMdi8RIPdAzSBT9LKKBJC+8Ocx DHCvn6WJdi9U58lPFkBQ1i5o5Oef8P2pvK/GIwylv+h/FnbmCvRL5OzSA2DNdht5ejz90QePV6F GqEVE+qbhDBN61jum2aecbwsFs0KnKK4CK/KQbHn7LFftLEo5dWNgRXTk0HiubJmmaLAtdB3j3s CDa3BL3KAkz1kKHEvj6RJRFmyCWNpvFAs1Exp01TUoFdkmaTfROva7jvol1iNgDOqpOFON27L4N kzZ8LE2GvneJeHkuFEV5xB84LhZUz0D65S4VcI6lm40tP5/HdJzm7MegN/qaY2/unV9h8RaxYOW 5e3KerYU6DAG41SOG8uqsEEh7tJfrZvBO1MCGnbIQyO4S/0V7Bq+zXijyskEzj3bXxJjCCRvFpu wahTmoPissmTAqpKiLQ== X-Proofpoint-ORIG-GUID: kB3pJ4wLEUyKh3m8mDOvvYKlW5_Xg91H X-Authority-Analysis: v=2.4 cv=W60IkxWk c=1 sm=1 tr=0 ts=69dd7f05 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=LI8zkurGpkgCOcO8t2sA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-13_03,2026-04-13_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 priorityscore=1501 spamscore=0 bulkscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604130229 On 4/13/2026 3:57 PM, Alex Williamson wrote: > On Mon, 13 Apr 2026 14:06:06 -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 >> Signed-off-by: Farhan Ali >> --- >> arch/s390/include/asm/pci.h | 3 +++ >> 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 | 31 +++++++++++++++++++++++++++++++ >> include/uapi/linux/vfio.h | 20 ++++++++++++++++++++ >> 6 files changed, 84 insertions(+) >> >> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h >> index 9a6a4eb9d7c1..9c8ee97d7e8a 100644 >> --- a/arch/s390/include/asm/pci.h >> +++ b/arch/s390/include/asm/pci.h >> @@ -360,6 +360,9 @@ 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); >> +void zpci_get_pending_error_and_count(struct zpci_dev *zdev, >> + struct zpci_ccdf_err *ccdf, >> + int *count); >> >> #ifdef CONFIG_NUMA >> >> diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c >> index c279a9f50a64..c8714d4a32fa 100644 >> --- a/arch/s390/pci/pci_event.c >> +++ b/arch/s390/pci/pci_event.c >> @@ -74,6 +74,25 @@ static void zpci_store_pci_error(struct pci_dev *pdev, >> zdev->pending_errs.count++; >> } >> >> +void zpci_get_pending_error_and_count(struct zpci_dev *zdev, >> + struct zpci_ccdf_err *ccdf, >> + int *count) >> +{ >> + int head = 0; > Unnecessary. Should also be a blank line between variable declaration > and code. > >> + *count = 0; > But why do we zero this and not ccdf? I had thought of memsetting ccdf to 0, but the only caller right already initializes to 0. So didn't think it was needed. > >> + >> + guard(mutex)(&zdev->pending_errs_lock); >> + if (zdev->pending_errs.count) { >> + 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--; >> + *count = zdev->pending_errs.count; >> + } >> +} > You've describe in the uAPI now how pec = 0 means no error, but why not > remove that ambiguity altogether and return -ENOMSG in that case. We > could start here and pass it through: > > { > int head; > > 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--; > *count = zdev->pending_errs.count; > > return 0; > } I had thought of returning an error (ENOENT was what I was going with), but perhaps I misunderstood your comment from v12 about specifying pec = 0 and pending error = 0 as not being an error. My assumption was as this is not an error we shouldn't return an error to userspace. >> +EXPORT_SYMBOL_GPL(zpci_get_pending_error_and_count); >> + >> 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 ad52abc46c04..5403730786a1 100644 >> --- a/drivers/vfio/pci/vfio_pci_core.c >> +++ b/drivers/vfio/pci/vfio_pci_core.c >> @@ -1534,6 +1534,8 @@ 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 0658095ac5b1..ee1647f0ffe6 100644 >> --- a/drivers/vfio/pci/vfio_pci_zdev.c >> +++ b/drivers/vfio/pci/vfio_pci_zdev.c >> @@ -141,6 +141,37 @@ 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 pending_errors = 0; >> + 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; >> + >> + zpci_get_pending_error_and_count(zdev, &ccdf, &pending_errors); >> + >> + err.version = 1; >> + err.pec = ccdf.pec; >> + err.pending_errors = pending_errors; >> + if (copy_to_user(arg, &err, sizeof(err))) >> + 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..2980ca39dd38 100644 >> --- a/include/uapi/linux/vfio.h >> +++ b/include/uapi/linux/vfio.h >> @@ -1534,6 +1534,26 @@ 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 s390x. On s390x, PCI error recovery >> + * involves platform firmware and notification to operating system 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 pending_errors provide any additional errors >> + * pending for the device, and userspace should read until zero. A value of >> + * 0 for pending_errors and pec would indicate no pending errors that need >> + * to be handled. >> + */ >> + >> +struct vfio_device_feature_zpci_err { >> + __u8 version; >> + __u8 pending_errors; >> + __u16 pec; >> +}; > I assume .version is for compatibility, but we don't define a strategy > for using it or specify what the version should be for this table. It > doesn't seem like there's actually an value-add to having it. Its possible we may need to extend this structure in the future if we want to report more information to userspace. I at least want the flexibility to do so. We had some discussion around this [1] in an earlier version. I was trying to follow similar versioning pattern we had around vfio-pci/zdev structures. [1] https://lore.kernel.org/all/88289f74-3d4f-4dd9-8f2a-8871d150fd50@linux.ibm.com/ > > I'm also not clear why we need to report .pending_errors. It mostly > seems like another ambiguous feature of this API. The value seems > volatile and the suggestion is to read until zero, so why provide the > value at all, the user can just read until -ENOMSG. Since we don't explicitly return an error indicating there are no available pci errors to handle, was why I added it. Is the preference to just return linux error code here? Thanks Farhan > > At that point, maybe we don't even need a return structure at all, > return small positive values for pec or -errno. The internal API could > match, avoiding the pass by address parameters. Thanks, > > Alex > > >> + >> +#define VFIO_DEVICE_FEATURE_ZPCI_ERROR 13 >> + >> /* -------- API for Type1 VFIO IOMMU -------- */ >> >> /**