Implement dma-buf get_tph for vfio-pci exported dma-bufs and add VFIO_DEVICE_FEATURE_DMA_BUF_TPH so userspace can publish TPH metadata for a VFIO-owned device.
8-bit ST and 16-bit Extended ST are distinct PCIe TPH namespaces; the uAPI carries both with explicit validity flags, and get_tph() returns the value matching the importer's requested namespace or -EOPNOTSUPP. Publish and read the TPH descriptor under dmabuf->resv, matching the locking used for other importer-visible dma-buf state. The SET ioctl takes dma_resv_lock_interruptible(), while the callback runs under DMA-buf's asserted resv lock. Reject requests the device cannot consume as a completer: pcie_tph_completer_type() must report at least PCI_EXP_DEVCAP2_TPH_COMP_TPH_ONLY, and Extended ST requires PCI_EXP_DEVCAP2_TPH_COMP_EXT_TPH. Validate fields before the completer check so userspace gets the narrowest errno. Signed-off-by: Zhiping Zhang <[email protected]> --- drivers/vfio/pci/vfio_pci_core.c | 3 + drivers/vfio/pci/vfio_pci_dmabuf.c | 94 +++++++++++++++++++++++++++++- drivers/vfio/pci/vfio_pci_priv.h | 12 ++++ include/uapi/linux/vfio.h | 37 ++++++++++++ 4 files changed, 145 insertions(+), 1 deletion(-) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 050e7542952e..4fa36f2f7555 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -1569,6 +1569,9 @@ 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_DMA_BUF_TPH: + return vfio_pci_core_feature_dma_buf_tph(vdev, flags, arg, + argsz); default: return -ENOTTY; } diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index 1a177ce7de54..0a0705c8dbea 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -3,6 +3,7 @@ */ #include <linux/dma-buf-mapping.h> #include <linux/pci-p2pdma.h> +#include <linux/pci-tph.h> #include <linux/dma-resv.h> #include "vfio_pci_priv.h" @@ -19,7 +20,12 @@ struct vfio_pci_dma_buf { u32 nr_ranges; struct kref kref; struct completion comp; - u8 revoked : 1; + u8 tph_st_valid:1; + u8 tph_st_ext_valid:1; + u8 tph_ph:2; + u8 tph_st; + u16 tph_st_ext; + u8 revoked:1; }; static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf, @@ -69,6 +75,26 @@ vfio_pci_dma_buf_map(struct dma_buf_attachment *attachment, return ret; } +static int vfio_pci_dma_buf_get_tph(struct dma_buf *dmabuf, bool extended, + u16 *steering_tag, u8 *ph) +{ + struct vfio_pci_dma_buf *priv = dmabuf->priv; + + dma_resv_assert_held(dmabuf->resv); + + if (extended) { + if (!priv->tph_st_ext_valid) + return -EOPNOTSUPP; + *steering_tag = priv->tph_st_ext; + } else { + if (!priv->tph_st_valid) + return -EOPNOTSUPP; + *steering_tag = priv->tph_st; + } + *ph = priv->tph_ph; + return 0; +} + static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment, struct sg_table *sgt, enum dma_data_direction dir) @@ -101,6 +127,7 @@ static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf) static const struct dma_buf_ops vfio_pci_dmabuf_ops = { .attach = vfio_pci_dma_buf_attach, + .get_tph = vfio_pci_dma_buf_get_tph, .map_dma_buf = vfio_pci_dma_buf_map, .unmap_dma_buf = vfio_pci_dma_buf_unmap, .release = vfio_pci_dma_buf_release, @@ -333,6 +360,71 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, return ret; } +int vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, + u32 flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz) +{ + struct vfio_device_feature_dma_buf_tph set_tph; + struct vfio_pci_dma_buf *priv; + struct dma_buf *dmabuf; + u8 comp; + int ret; + + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, + sizeof(set_tph)); + if (ret != 1) + return ret; + + if (copy_from_user(&set_tph, arg, sizeof(set_tph))) + return -EFAULT; + + if (set_tph.flags & ~(VFIO_DMA_BUF_TPH_ST | VFIO_DMA_BUF_TPH_ST_EXT)) + return -EINVAL; + + if (set_tph.ph & ~0x3) + return -EINVAL; + + comp = pcie_tph_completer_type(vdev->pdev); + if (comp == PCI_EXP_DEVCAP2_TPH_COMP_NONE) + return -EOPNOTSUPP; + if ((set_tph.flags & VFIO_DMA_BUF_TPH_ST_EXT) && + comp != PCI_EXP_DEVCAP2_TPH_COMP_EXT_TPH) + return -EOPNOTSUPP; + + dmabuf = dma_buf_get(set_tph.dmabuf_fd); + if (IS_ERR(dmabuf)) + return PTR_ERR(dmabuf); + + if (dmabuf->ops != &vfio_pci_dmabuf_ops) { + ret = -EINVAL; + goto out_put; + } + + priv = dmabuf->priv; + if (priv->vdev != vdev) { + ret = -EINVAL; + goto out_put; + } + + ret = dma_resv_lock_interruptible(dmabuf->resv, NULL); + if (ret) + goto out_put; + + priv->tph_st = set_tph.steering_tag; + priv->tph_st_ext = set_tph.steering_tag_ext; + priv->tph_ph = set_tph.ph; + priv->tph_st_valid = !!(set_tph.flags & VFIO_DMA_BUF_TPH_ST); + priv->tph_st_ext_valid = + !!(set_tph.flags & VFIO_DMA_BUF_TPH_ST_EXT); + dma_resv_unlock(dmabuf->resv); + ret = 0; + +out_put: + dma_buf_put(dmabuf); + return ret; +} + void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked) { struct vfio_pci_dma_buf *priv; diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h index fca9d0dfac90..c58f369be4b3 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -118,6 +118,10 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev) int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, struct vfio_device_feature_dma_buf __user *arg, size_t argsz); +int vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, + u32 flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz); void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev); void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked); #else @@ -128,6 +132,14 @@ vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, { return -ENOTTY; } + +static inline int +vfio_pci_core_feature_dma_buf_tph(struct vfio_pci_core_device *vdev, u32 flags, + struct vfio_device_feature_dma_buf_tph __user *arg, + size_t argsz) +{ + return -ENOTTY; +} static inline void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev) { } diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 5de618a3a5ee..5dd693220a0d 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -1534,6 +1534,43 @@ struct vfio_device_feature_dma_buf { */ #define VFIO_DEVICE_FEATURE_MIG_PRECOPY_INFOv2 12 +/** + * Upon VFIO_DEVICE_FEATURE_SET associate TPH (TLP Processing Hints) metadata + * with a vfio-exported dma-buf. The dma-buf must have been created by + * VFIO_DEVICE_FEATURE_DMA_BUF on this device, and the device must report + * TPH Completer support in Device Capabilities 2 (bits 13:12); requests + * carrying VFIO_DMA_BUF_TPH_ST_EXT additionally require the device to + * report the Extended TPH Completer encoding. Otherwise the ioctl + * returns -EOPNOTSUPP. + * + * dmabuf_fd is the file descriptor returned by VFIO_DEVICE_FEATURE_DMA_BUF. + * + * 8-bit ST (steering_tag) and 16-bit Extended ST (steering_tag_ext) are + * distinct namespaces. Userspace supplies whichever values are valid and sets + * the matching VFIO_DMA_BUF_TPH_ST / VFIO_DMA_BUF_TPH_ST_EXT bits in @flags; + * an importer requests one namespace and receives the matching value. + * + * @flags == 0 marks any previously published ST / Extended-ST as invalid + * for future get_tph() requests on this dma-buf. + * + * ph is the 2-bit TLP Processing Hint and must be in the range [0, 3]. + * + * Userspace must publish TPH before handing the dma-buf fd to an importer. + * Calling SET again replaces the published values. + */ +#define VFIO_DEVICE_FEATURE_DMA_BUF_TPH 13 + +#define VFIO_DMA_BUF_TPH_ST (1 << 0) +#define VFIO_DMA_BUF_TPH_ST_EXT (1 << 1) + +struct vfio_device_feature_dma_buf_tph { + __s32 dmabuf_fd; + __u32 flags; + __u16 steering_tag_ext; + __u8 steering_tag; + __u8 ph; +}; + /* -------- API for Type1 VFIO IOMMU -------- */ /** -- 2.53.0-Meta
