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Mon, 5 Oct 2026 15:47:26 +0000 (GMT) Received: from Mac.ibm.com (unknown [9.61.252.89]) by smtpav01.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 5 Oct 2026 15:47:26 +0000 (GMT) From: Omar Elghoul To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: oelghoul@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, schnelle@linux.ibm.com, mjrosato@linux.ibm.com, alifm@linux.ibm.com, farman@linux.ibm.com, gbayer@linux.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, frankja@linux.ibm.com, imbrenda@linux.ibm.com Subject: [PATCH v8 4/4] vfio-pci/zdev: Add VFIO FMB device features Date: Mon, 5 Oct 2026 11:45:57 -0400 Message-ID: <20261005154557.57801-5-oelghoul@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261005154557.57801-1-oelghoul@linux.ibm.com> References: <20261005154557.57801-1-oelghoul@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA1MDA2MSBTYWx0ZWRfX98AVjlWbZ/pW M1pk9O2bRNzwGAW7STxdxFVDZEcwY72A7WoLeXscMA1QoRPugBi0z6cpXMYulpQcJPzxFPW3XOM 1YIQG+t2nCAU5ozkt2cj4oLF4BhhSvc= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA1MDA2MSBTYWx0ZWRfX/2fP0JuQLsj6 rHhZaSTQk6tk0kaP0vAlPyLZjN/vjhOg4kJQmCixmT6AWk6tQ3cJYxMT3HnirzQzv1ffVQBJzIC 0Cq87Gge6Jz51eQvtxafxHJseRftXagahqZBWcy/CoKR0X50cbePzPYvy67NsTnRrw9OvKPLEw7 Gm0u+78ODo01noJach0jpkAJYjVbNi0YAG1mh16VShfm5bwkRoAcJ4OPIMgxRchx5gJPqePR4WI +WvX16Bp6Vw8P1vf+0BPKPWgdo+l9N+YnfqW2hleQxdn3m2NPU1Yv+UtgU8ew3zxYfwQ4g4xtLd 2Ujz8nrmeEfW2eM2eHgPUCLNzkEk+eYrW7Oz1DUgGe0GyrwqCFtiNCSOh8Ct6VBGv9Csg4UT0aw FR1LErS/jkDSS4diPHmG4iwD6jzGURgdq+YAsU8hsIJlG37lW7Fk6ls6yFGhPW3LhQlmx8fR1c5 FeFs8DRc8+EHK2V5Whw== X-Proofpoint-GUID: qCl-H0S_4eCRovyIOI9eUJlCBzZg4ECX X-Authority-Analysis: v=2.4 cv=UNRIjyfy c=1 sm=1 tr=0 ts=6ac3c694 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=wtvrgtD0Hc2VqHSVShsA:9 X-Proofpoint-ORIG-GUID: qCl-H0S_4eCRovyIOI9eUJlCBzZg4ECX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-05_04,2026-10-05_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610050061 Introduce new VFIO features for zPCI devices to provide FMB passthrough to userspace. Allow the user to enable or disable the FMB using the SET-only feature VFIO_DEVICE_FEATURE_ZPCI_FMB_ENABLE. Likewise allow the user to read the latest FMB using the GET-only feature VFIO_DEVICE_FEATURE_ZPCI_FMB_READ in the case when the FMB is enabled. Signed-off-by: Omar Elghoul --- drivers/vfio/pci/vfio_pci_core.c | 4 +++ drivers/vfio/pci/vfio_pci_priv.h | 18 ++++++++++ drivers/vfio/pci/vfio_pci_zdev.c | 57 ++++++++++++++++++++++++++++++++ include/uapi/linux/vfio.h | 29 ++++++++++++++++ 4 files changed, 108 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 6757054e9d87..3c827a77725b 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -1627,6 +1627,10 @@ int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags, 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); + case VFIO_DEVICE_FEATURE_ZPCI_FMB_ENABLE: + return vfio_pci_zdev_feature_fmb_enable(vdev, flags, arg, argsz); + case VFIO_DEVICE_FEATURE_ZPCI_FMB_READ: + return vfio_pci_zdev_feature_fmb_read(vdev, 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 4e7162234a2e..e04d7e9d0c30 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -95,6 +95,10 @@ 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); +int vfio_pci_zdev_feature_fmb_enable(struct vfio_pci_core_device *vdev, u32 flags, + void __user *arg, size_t argsz); +int vfio_pci_zdev_feature_fmb_read(struct vfio_pci_core_device *vdev, 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) @@ -116,6 +120,20 @@ static inline int vfio_pci_zdev_feature_err(struct vfio_device *device, { return -ENOTTY; } + +static inline int vfio_pci_zdev_feature_fmb_enable(struct vfio_pci_core_device *vdev, + u32 flags, void __user *arg, + size_t argsz) +{ + return -ENOTTY; +} + +static inline int vfio_pci_zdev_feature_fmb_read(struct vfio_pci_core_device *vdev, + 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 f47f36314a1c..acf4bbcb53f6 100644 --- a/drivers/vfio/pci/vfio_pci_zdev.c +++ b/drivers/vfio/pci/vfio_pci_zdev.c @@ -219,3 +219,60 @@ void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev) if (zpci_kvm_hook.kvm_unregister) zpci_kvm_hook.kvm_unregister(zdev); } + +int vfio_pci_zdev_feature_fmb_enable(struct vfio_pci_core_device *vdev, u32 flags, + void __user *arg, size_t argsz) +{ + struct zpci_dev *zdev; + struct vfio_device_feature_zpci_fmb_enable fmb_enable; + int ret; + + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, sizeof(fmb_enable)); + if (ret != 1) + return ret; + + zdev = to_zpci(vdev->pdev); + if (!zdev) + return -ENODEV; + + if (copy_from_user(&fmb_enable, arg, sizeof(fmb_enable))) + return -EFAULT; + + guard(mutex)(&zdev->fmb_lock); + + if (fmb_enable.enabled) + return zpci_fmb_reenable_device(zdev); + return zpci_fmb_disable_device(zdev); +} + +int vfio_pci_zdev_feature_fmb_read(struct vfio_pci_core_device *vdev, u32 flags, + void __user *arg, size_t argsz) +{ + struct zpci_dev *zdev; + struct vfio_device_feature_zpci_fmb_read fmb_read; + struct zpci_fmb fmb_bounce; + int ret; + + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET, sizeof(fmb_read)); + if (ret != 1) + return ret; + + zdev = to_zpci(vdev->pdev); + if (!zdev) + return -ENODEV; + + if (copy_from_user(&fmb_read, arg, sizeof(fmb_read))) + return -EFAULT; + if (!fmb_read.data) + return -EINVAL; + + scoped_guard(mutex, &zdev->fmb_lock) { + if (!zdev->fmb_enabled) + return -ENOMSG; + memcpy(&fmb_bounce, zdev->fmb, zdev->fmb_length); + } + + if (copy_to_user(u64_to_user_ptr(fmb_read.data), &fmb_bounce, zdev->fmb_length)) + return -EFAULT; + return 0; +} diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index e41437fa17ad..a8d501e42ef9 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1555,6 +1555,35 @@ struct vfio_device_feature_zpci_err { #define VFIO_DEVICE_FEATURE_ZPCI_ERROR 13 +/** + * Upon VFIO_DEVICE_FEATURE_SET, enable or disable FMB for the VFIO zPCI device. + * + * enabled is treated as a bool, so any non-zero value evaluates to true. Nested + * enabling resets the FMB counters to zero, and nested disabling fails. + * + * Returns: 0 on success, -1 and errno set appropriately on error. + */ +#define VFIO_DEVICE_FEATURE_ZPCI_FMB_ENABLE 14 + +struct vfio_device_feature_zpci_fmb_enable { + __u8 enabled; +}; + +/** + * Upon VFIO_DEVICE_FEATURE_GET, provide FMB passthrough for VFIO zPCI devices. + * + * The user-provided buffer must be at least fmb_length large, where fmb_length + * is reported in VFIO_DEVICE_INFO_CAP_ZPCI_BASE. + * + * Returns: 0 on success, -1 and errno set appropriately on error. errno==ENOMSG + * when the FMB is not enabled. + */ +#define VFIO_DEVICE_FEATURE_ZPCI_FMB_READ 15 + +struct vfio_device_feature_zpci_fmb_read { + __aligned_u64 data; +}; + /* -------- API for Type1 VFIO IOMMU -------- */ /** -- 2.55.0