Allow userspace to obtain CMB memory by mmaping the controller's char device. The mmap call allocates and returns a hunk of CMB memory, (the offset is ignored) so userspace does not have control over the address within the CMB. A VMA allocated in this way will only be usable by drivers that set FOLL_PCI_P2PDMA when calling GUP. And inter-device support will be checked the first time the pages are mapped for DMA. Currently this is only supported by O_DIRECT to an PCI NVMe device or through the NVMe passthrough IOCTL. Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> --- drivers/nvme/host/core.c | 35 +++++++++++++++++++++++++++++++---- drivers/nvme/host/nvme.h | 3 +++ drivers/nvme/host/pci.c | 23 +++++++++++++++++++++++ 3 files changed, 57 insertions(+), 4 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index d6e76f2dc293..23fe4b544bf1 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -3166,6 +3166,7 @@ static int nvme_dev_open(struct inode *inode, struct file *file) { struct nvme_ctrl *ctrl = container_of(inode->i_cdev, struct nvme_ctrl, cdev); + int ret = -EINVAL; switch (ctrl->state) { case NVME_CTRL_LIVE: @@ -3175,13 +3176,25 @@ static int nvme_dev_open(struct inode *inode, struct file *file) } nvme_get_ctrl(ctrl); - if (!try_module_get(ctrl->ops->module)) { - nvme_put_ctrl(ctrl); - return -EINVAL; - } + if (!try_module_get(ctrl->ops->module)) + goto err_put_ctrl; file->private_data = ctrl; + + if (ctrl->ops->cdev_file_open) { + ret = ctrl->ops->cdev_file_open(ctrl, file); + if (ret) + goto err_put_mod; + } + return 0; + +err_put_mod: + module_put(ctrl->ops->module); +err_put_ctrl: + nvme_put_ctrl(ctrl); + return ret; + } static int nvme_dev_release(struct inode *inode, struct file *file) @@ -3189,11 +3202,24 @@ static int nvme_dev_release(struct inode *inode, struct file *file) struct nvme_ctrl *ctrl = container_of(inode->i_cdev, struct nvme_ctrl, cdev); + if (ctrl->ops->cdev_file_release) + ctrl->ops->cdev_file_release(file); + module_put(ctrl->ops->module); nvme_put_ctrl(ctrl); return 0; } +static int nvme_dev_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct nvme_ctrl *ctrl = file->private_data; + + if (!ctrl->ops->mmap_cmb) + return -ENODEV; + + return ctrl->ops->mmap_cmb(ctrl, vma); +} + static const struct file_operations nvme_dev_fops = { .owner = THIS_MODULE, .open = nvme_dev_open, @@ -3201,6 +3227,7 @@ static const struct file_operations nvme_dev_fops = { .unlocked_ioctl = nvme_dev_ioctl, .compat_ioctl = compat_ptr_ioctl, .uring_cmd = nvme_dev_uring_cmd, + .mmap = nvme_dev_mmap, }; static ssize_t nvme_sysfs_reset(struct device *dev, diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 957f79420cf3..44ff05d8e24d 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -503,6 +503,9 @@ struct nvme_ctrl_ops { void (*delete_ctrl)(struct nvme_ctrl *ctrl); int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size); bool (*supports_pci_p2pdma)(struct nvme_ctrl *ctrl); + int (*cdev_file_open)(struct nvme_ctrl *ctrl, struct file *file); + void (*cdev_file_release)(struct file *file); + int (*mmap_cmb)(struct nvme_ctrl *ctrl, struct vm_area_struct *vma); }; /* diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 52b52a7efa9a..8ef3752b7ddb 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -2972,6 +2972,26 @@ static bool nvme_pci_supports_pci_p2pdma(struct nvme_ctrl *ctrl) return dma_pci_p2pdma_supported(dev->dev); } +static int nvme_pci_cdev_file_open(struct nvme_ctrl *ctrl, struct file *file) +{ + struct pci_dev *pdev = to_pci_dev(to_nvme_dev(ctrl)->dev); + + return pci_p2pdma_file_open(pdev, file); +} + +static void nvme_pci_cdev_file_release(struct file *file) +{ + pci_p2pdma_file_release(file); +} + +static int nvme_pci_mmap_cmb(struct nvme_ctrl *ctrl, + struct vm_area_struct *vma) +{ + struct pci_dev *pdev = to_pci_dev(to_nvme_dev(ctrl)->dev); + + return pci_mmap_p2pmem(pdev, vma); +} + static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = { .name = "pcie", .module = THIS_MODULE, @@ -2983,6 +3003,9 @@ static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = { .submit_async_event = nvme_pci_submit_async_event, .get_address = nvme_pci_get_address, .supports_pci_p2pdma = nvme_pci_supports_pci_p2pdma, + .cdev_file_open = nvme_pci_cdev_file_open, + .cdev_file_release = nvme_pci_cdev_file_release, + .mmap_cmb = nvme_pci_mmap_cmb, }; static int nvme_dev_map(struct nvme_dev *dev) -- 2.30.2