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Wed, 11 Nov 2026 16:28:36 +0000 (GMT) Received: from localhost.localdomain (unknown [9.61.243.186]) by smtpav02.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 11 Nov 2026 16:28:36 +0000 (GMT) From: Omar Elghoul To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: 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 v13 5/5] vfio-pci/zdev: Add VFIO FMB device features Date: Wed, 11 Nov 2026 11:27:58 -0500 Message-ID: <20261111162758.9792-6-oelghoul@linux.ibm.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261111162758.9792-1-oelghoul@linux.ibm.com> References: <20261111162758.9792-1-oelghoul@linux.ibm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=J+M/fwnS c=1 sm=1 tr=0 ts=6af497ba cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=r1p2_3pzAAAA:8 a=o7ZLYlnJ96k-dGTR9YsA:9 a=r_pkcD-q9-ctt7trBg_g:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTExMDA2NCBTYWx0ZWRfX7lsbbIrtpkpv 07H+FwlHea+2qUdNBF55xKppqK8IRl/+SrMe1OoToV7MGTH9xqP3hbolSq1cZXAK32QyomCIsAS /4z32MTVtZm/sxO8DnyFzGX8uoEGxN1r+9WqTs3k8T8OMQLTOnm/FHfsk+9OvX3r6SmDPgrd5Wd D6qeByUlYAZqBWeoJjK9DqF3cXNfb36Poz8tEtuK7557KvQz7MCSVzdAAtG046aBckAt9GFL0Tc tbHLDI/3TLlMZnUxr/rw0xlM02pBDuDjkAfWkUL+gGiNXLu0TGuw0Qn2TWuWZEXHlwywSGRc9mL qOvaDdFipKUPITEA+8endSOy/SHR6Q7QtOY2rxVO2cxD8VlhcZ7eW+E/AFlBWKJOAb3HLg84NoY dY3lWHo/vzJDjNmVE0hNSCe5JM1GvYaCLEJFrlTOGvonM1hvExva7ZNdGaxyJMR7tPaDYlFT7Su Vfj0yqb+aKaMUDMw4IQ== X-Proofpoint-Spam-Info: AW1haW4tMjYxMTExMDA2NCBTYWx0ZWRfXwAtMmfLBCOrU UsWs1GL1fEZl+no+EgeNG/5hPtMm4UE6MPqv8173iF2OsR1/uyyqfMernokkgdGuuPFt/V7uhSP xqbj0OqOhzzQrUhDp/YI2abO0pdB/3g= X-Proofpoint-GUID: a5w50A6Pq-dkwuIo8961GTo6Bu4wZ0TF X-Proofpoint-ORIG-GUID: a5w50A6Pq-dkwuIo8961GTo6Bu4wZ0TF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-11_04,2026-11-11_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 bulkscore=0 adultscore=0 suspectscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611110064 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 Acked-by: Alex Williamson Reviewed-by: Niklas Schnelle Reviewed-by: Matthew Rosato --- drivers/vfio/pci/vfio_pci_core.c | 4 ++ drivers/vfio/pci/vfio_pci_priv.h | 18 +++++++++ drivers/vfio/pci/vfio_pci_zdev.c | 64 ++++++++++++++++++++++++++++++++ include/uapi/linux/vfio.h | 30 +++++++++++++++ 4 files changed, 116 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index fcbb2da860e2..f2d5b6857925 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -1614,6 +1614,10 @@ 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..0584fbaf8755 100644 --- a/drivers/vfio/pci/vfio_pci_zdev.c +++ b/drivers/vfio/pci/vfio_pci_zdev.c @@ -219,3 +219,67 @@ 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) { + ret = zpci_fmb_request_off(zdev); + if (ret && ret != -EINVAL) + return ret; + + return zpci_fmb_request_on(zdev); + } + + return zpci_fmb_request_off(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..7e9adb61c5e1 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1555,6 +1555,36 @@ 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 disables and re-enables the FMB, while nested disabling fails with + * EINVAL. + * + * 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. If measurement is not enabled, + * fail with ENOMSG. + * + * Returns: 0 on success, -1 and errno set appropriately on error. + */ +#define VFIO_DEVICE_FEATURE_ZPCI_FMB_READ 15 + +struct vfio_device_feature_zpci_fmb_read { + __aligned_u64 data; +}; + /* -------- API for Type1 VFIO IOMMU -------- */ /** -- 2.56.0