Under nested IOMMU translation, userspace owns the stage-1 translation structure (e.g. the stage-1 page table of Intel VT-d or the context table of ARM SMMUv3, and etc.). Such stage-1 translation structures are vendor specific, and needs to be compatiable with the underlying IOMMU hardware. Hence, userspace should know the IOMMU hardware capability before creating and configuring the stage-1 translation structure to kernel.
This adds ioctl: IOMMU_DEVICE_GET_INFO to query the IOMMU hardware capability for a given device. The returned data is vendor specific, userspace can tell it by the @out_device_type field.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com Signed-off-by: Yi Liu yi.l.liu@intel.com --- drivers/iommu/iommufd/device.c | 72 +++++++++++++++++++++++++ drivers/iommu/iommufd/iommufd_private.h | 1 + drivers/iommu/iommufd/main.c | 3 ++ include/uapi/linux/iommufd.h | 36 +++++++++++++ 4 files changed, 112 insertions(+)
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c index 8a9834fc129a..3b64aef24807 100644 --- a/drivers/iommu/iommufd/device.c +++ b/drivers/iommu/iommufd/device.c @@ -134,6 +134,78 @@ void iommufd_device_unbind(struct iommufd_device *idev) } EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
+static int iommufd_zero_fill_user(u64 ptr, int bytes) +{ + int index = 0; + + for (; index < bytes; index++) { + if (put_user(0, (uint8_t __user *)(ptr + index))) + return -EFAULT; + } + return 0; +} + +int iommufd_device_get_info(struct iommufd_ucmd *ucmd) +{ + struct iommu_device_info *cmd = ucmd->cmd; + struct iommufd_object *dev_obj; + struct device *dev; + const struct iommu_ops *ops; + void *data; + unsigned int length, data_len; + int rc; + + if (cmd->flags || cmd->__reserved || !cmd->data_len) + return -EOPNOTSUPP; + + dev_obj = iommufd_get_object(ucmd->ictx, cmd->dev_id, + IOMMUFD_OBJ_DEVICE); + if (IS_ERR(dev_obj)) + return PTR_ERR(dev_obj); + + dev = container_of(dev_obj, struct iommufd_device, obj)->dev; + + ops = dev_iommu_ops(dev); + if (!ops || !ops->hw_info) { + rc = -EOPNOTSUPP; + goto out_put; + } + + data = ops->hw_info(dev, &data_len); + if (IS_ERR(data)) { + rc = PTR_ERR(data); + goto out_put; + } + + length = min(cmd->data_len, data_len); + if (copy_to_user(u64_to_user_ptr(cmd->data_ptr), data, length)) { + rc = -EFAULT; + goto out_free_data; + } + + /* + * Zero the trailing bytes for userspace if the buffer is bigger + * than the data size kernel actually has. + */ + if (length < cmd->data_len) { + rc = iommufd_zero_fill_user(cmd->data_ptr + length, + cmd->data_len - length); + if (rc) + goto out_free_data; + } + + cmd->out_device_type = ops->driver_type; + cmd->data_len = data_len; + + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); + +out_free_data: + kfree(data); +out_put: + iommufd_put_object(dev_obj); + return rc; +} + static int iommufd_device_setup_msi(struct iommufd_device *idev, struct iommufd_hw_pagetable *hwpt, phys_addr_t sw_msi_start) diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 200c783800ad..4a0a1a7fdae1 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -258,6 +258,7 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, void iommufd_hw_pagetable_destroy(struct iommufd_object *obj);
void iommufd_device_destroy(struct iommufd_object *obj); +int iommufd_device_get_info(struct iommufd_ucmd *ucmd);
struct iommufd_access { struct iommufd_object obj; diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 3fbe636c3d8a..59aa30ad1090 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -250,6 +250,7 @@ static int iommufd_option(struct iommufd_ucmd *ucmd)
union ucmd_buffer { struct iommu_destroy destroy; + struct iommu_device_info info; struct iommu_ioas_alloc alloc; struct iommu_ioas_allow_iovas allow_iovas; struct iommu_ioas_copy ioas_copy; @@ -281,6 +282,8 @@ struct iommufd_ioctl_op { } static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = { IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id), + IOCTL_OP(IOMMU_DEVICE_GET_INFO, iommufd_device_get_info, struct iommu_device_info, + __reserved), IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl, struct iommu_ioas_alloc, out_ioas_id), IOCTL_OP(IOMMU_IOAS_ALLOW_IOVAS, iommufd_ioas_allow_iovas, diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h index fda75c8450ee..6cfe102f26f3 100644 --- a/include/uapi/linux/iommufd.h +++ b/include/uapi/linux/iommufd.h @@ -45,6 +45,7 @@ enum { IOMMUFD_CMD_IOAS_UNMAP, IOMMUFD_CMD_OPTION, IOMMUFD_CMD_VFIO_IOAS, + IOMMUFD_CMD_DEVICE_GET_INFO, };
/** @@ -371,4 +372,39 @@ struct iommu_device_info_vtd { __aligned_u64 cap_reg; __aligned_u64 ecap_reg; }; + +/** + * struct iommu_device_info - ioctl(IOMMU_DEVICE_GET_INFO) + * @size: sizeof(struct iommu_device_info) + * @flags: Must be 0 + * @dev_id: The device being attached to the IOMMU + * @data_len: Input the type specific data buffer length in bytes + * @data_ptr: Pointer to the type specific structure (e.g. + * struct iommu_device_info_vtd) + * @out_device_type: Output the underlying iommu hardware type, it is + * one of enum iommu_device_data_type. + * @__reserved: Must be 0 + * + * Query the hardware iommu capability for given device which has been + * bound to iommufd. @data_len is set to be the size of the buffer to + * type specific data and the data will be filled. Trailing bytes are + * zeroed if the user buffer is larger than the data kernel has. + * + * The type specific data would be used to sync capability between the + * vIOMMU and the hardware IOMMU, also for the availabillity checking of + * iommu hardware features like dirty page tracking in I/O page table. + * + * The @out_device_type will be filled if the ioctl succeeds. It would + * be used to decode the data filled in the buffer pointed by @data_ptr. + */ +struct iommu_device_info { + __u32 size; + __u32 flags; + __u32 dev_id; + __u32 data_len; + __aligned_u64 data_ptr; + __u32 out_device_type; + __u32 __reserved; +}; +#define IOMMU_DEVICE_GET_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_GET_INFO) #endif