Re: [PATCH v2 06/11] iommufd: IOMMU_HWPT_ALLOC allocation with user data

["Liu, Jingqi" <jingqi.liu@intel.com>]

On 5/11/2023 10:38 PM, Yi Liu wrote:
> IOMMU_HWPT_ALLOC already supports iommu_domain allocation for usersapce.
> But it can only allocate hw_pagetables linked with IOAS. There are needs
> to support hw_pagetable allocation with parameters specified by user. For
> example, in nested translation, user needs to allocate hw_pagetable for
> the stage-1 translation (e.g. a single I/O page table or a set of I/O page
> tables) with user data. It also needs provide a stage-2 hw_pagetable which
s/provide/to provide
> is linked to the GPA IOAS.
>
> This extends IOMMU_HWPT_ALLOC to accept user specified parameter and hwpt
> ID in @pt_id field. Such as the user-managed stage-1 hwpt, which requires
> a parent hwpt to point to stage-2 translation.
>
> enum iommu_hwpt_type is defined to differentiate the user parameters use
> by different usages. For the allocations that don't require user parameter,
s/parameter/parameters
> IOMMU_HWPT_TYPE_DEFAULT is defined for backward compatibility. Other types
> would be added by future iommu vendor driver extensions.
>
> Co-developed-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>   drivers/iommu/iommufd/hw_pagetable.c | 87 +++++++++++++++++++++++++---
>   drivers/iommu/iommufd/main.c         |  2 +-
>   include/uapi/linux/iommufd.h         | 32 +++++++++-
>   3 files changed, 112 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
> index 73d7d9d07726..e84270eb6e49 100644
> --- a/drivers/iommu/iommufd/hw_pagetable.c
> +++ b/drivers/iommu/iommufd/hw_pagetable.c
> @@ -184,11 +184,15 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
>   
>   int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
>   {
> +	struct iommufd_hw_pagetable *hwpt, *parent = NULL;
> +	union iommu_domain_user_data *data = NULL;
>   	struct iommu_hwpt_alloc *cmd = ucmd->cmd;
> -	struct iommufd_hw_pagetable *hwpt;
> +	struct iommufd_object *pt_obj;
> +	const struct iommu_ops *ops;
>   	struct iommufd_device *idev;
>   	struct iommufd_ioas *ioas;
> -	int rc;
> +	int klen = 0;
> +	int rc = 0;
>   
>   	if (cmd->flags || cmd->__reserved)
>   		return -EOPNOTSUPP;
> @@ -197,15 +201,81 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
>   	if (IS_ERR(idev))
>   		return PTR_ERR(idev);
>   
> -	ioas = iommufd_get_ioas(ucmd->ictx, cmd->pt_id);
> -	if (IS_ERR(ioas)) {
> -		rc = PTR_ERR(ioas);
> +	ops = dev_iommu_ops(idev->dev);
> +
> +	/*
> +	 * All drivers support IOMMU_HWPT_TYPE_DEFAULT, so pass it through.
> +	 * For any other hwpt_type, check the ops->domain_alloc_user_data_len
> +	 * presence and its result.
> +	 */
> +	if (cmd->hwpt_type != IOMMU_HWPT_TYPE_DEFAULT) {
> +		if (!ops->domain_alloc_user_data_len) {
> +			rc = -EOPNOTSUPP;
> +			goto out_put_idev;
> +		}
> +		klen = ops->domain_alloc_user_data_len(cmd->hwpt_type);
> +		if (WARN_ON(klen < 0)) {
> +			rc = -EINVAL;
> +			goto out_put_pt;
> +		}
Would it be better if the later check "klen" is moved here ?
     if (klen) {
                 [...]
     }
If this check fails here, there's no need to execute the code after it.
If this path is not executed, "klen" is 0, and there's no need to check it.
Do I understand it right ?

Thanks,
Jingqi
> +	}
> +
> +	pt_obj = iommufd_get_object(ucmd->ictx, cmd->pt_id, IOMMUFD_OBJ_ANY);
> +	if (IS_ERR(pt_obj)) {
> +		rc = -EINVAL;
>   		goto out_put_idev;
>   	}
>   
> +	switch (pt_obj->type) {
> +	case IOMMUFD_OBJ_IOAS:
> +		ioas = container_of(pt_obj, struct iommufd_ioas, obj);
> +		break;
> +	case IOMMUFD_OBJ_HW_PAGETABLE:
> +		/* pt_id points HWPT only when hwpt_type is !IOMMU_HWPT_TYPE_DEFAULT */
> +		if (cmd->hwpt_type == IOMMU_HWPT_TYPE_DEFAULT) {
> +			rc = -EINVAL;
> +			goto out_put_pt;
> +		}
> +
> +		parent = container_of(pt_obj, struct iommufd_hw_pagetable, obj);
> +		/*
> +		 * Cannot allocate user-managed hwpt linking to auto_created
> +		 * hwpt. If the parent hwpt is already a user-managed hwpt,
> +		 * don't allocate another user-managed hwpt linking to it.
> +		 */
> +		if (parent->auto_domain || parent->parent) {
> +			rc = -EINVAL;
> +			goto out_put_pt;
> +		}
> +		ioas = parent->ioas;
> +		break;
> +	default:
> +		rc = -EINVAL;
> +		goto out_put_pt;
> +	}
> +
> +	if (klen) {
> +		if (!cmd->data_len) {
> +			rc = -EINVAL;
> +			goto out_put_pt;
> +		}
> +
> +		data = kzalloc(sizeof(*data), GFP_KERNEL);
> +		if (!data) {
> +			rc = -ENOMEM;
> +			goto out_put_pt;
> +		}
> +
> +		rc = copy_struct_from_user(data, sizeof(*data),
> +					   u64_to_user_ptr(cmd->data_uptr),
> +					   cmd->data_len);
> +		if (rc)
> +			goto out_free_data;
> +	}
> +
>   	mutex_lock(&ioas->mutex);
>   	hwpt = iommufd_hw_pagetable_alloc(ucmd->ictx, ioas, idev,
> -					  NULL, NULL, false);
> +					  parent, data, false);
>   	if (IS_ERR(hwpt)) {
>   		rc = PTR_ERR(hwpt);
>   		goto out_unlock;
> @@ -222,7 +292,10 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
>   	iommufd_object_abort_and_destroy(ucmd->ictx, &hwpt->obj);
>   out_unlock:
>   	mutex_unlock(&ioas->mutex);
> -	iommufd_put_object(&ioas->obj);
> +out_free_data:
> +	kfree(data);
> +out_put_pt:
> +	iommufd_put_object(pt_obj);
>   out_put_idev:
>   	iommufd_put_object(&idev->obj);
>   	return rc;
> diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
> index 5c24e8971f09..ac81403ba78e 100644
> --- a/drivers/iommu/iommufd/main.c
> +++ b/drivers/iommu/iommufd/main.c
> @@ -302,7 +302,7 @@ 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_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
> -		 __reserved),
> +		 data_uptr),
>   	IOCTL_OP(IOMMU_DEVICE_GET_HW_INFO, iommufd_device_get_hw_info,
>   		 struct iommu_hw_info, __reserved),
>   	IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index e9d42838dcbd..699e735828db 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -347,6 +347,14 @@ struct iommu_vfio_ioas {
>   };
>   #define IOMMU_VFIO_IOAS _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VFIO_IOAS)
>   
> +/**
> + * enum iommu_hwpt_type - IOMMU HWPT Type
> + * @IOMMU_HWPT_TYPE_DEFAULT: default
> + */
> +enum iommu_hwpt_type {
> +	IOMMU_HWPT_TYPE_DEFAULT,
> +};
> +
>   /**
>    * struct iommu_hwpt_alloc - ioctl(IOMMU_HWPT_ALLOC)
>    * @size: sizeof(struct iommu_hwpt_alloc)
> @@ -355,12 +363,31 @@ struct iommu_vfio_ioas {
>    * @pt_id: The IOAS to connect this HWPT to
>    * @out_hwpt_id: The ID of the new HWPT
>    * @__reserved: Must be 0
> + * @hwpt_type: One of enum iommu_hwpt_type
> + * @data_len: Length of the type specific data
> + * @data_uptr: User pointer to the type specific data
>    *
>    * Explicitly allocate a hardware page table object. This is the same object
>    * type that is returned by iommufd_device_attach() and represents the
>    * underlying iommu driver's iommu_domain kernel object.
>    *
> - * A HWPT will be created with the IOVA mappings from the given IOAS.
> + * A kernel-managed HWPT will be created with the mappings from the given IOAS.
> + * The @hwpt_type for its allocation can be set to IOMMU_HWPT_TYPE_DEFAULT, or
> + * another type (being listed below) to specialize a kernel-managed HWPT.
> + *
> + * A user-managed HWPT will be created from a given parent HWPT via @pt_id, in
> + * which the parent HWPT must be allocated previously via the same ioctl from a
> + * given IOAS. The @hwpt_type must not be set to IOMMU_HWPT_TYPE_DEFAULT but a
> + * pre-defined type corresponding to the underlying IOMMU hardware.
> + *
> + * If the @hwpt_type is set to IOMMU_HWPT_TYPE_DEFAULT, both the @data_len and
> + * the @data_uptr will be ignored. Otherwise, both of them must be given.
> + *
> + * +==============================+=====================================+===========+
> + * | @hwpt_type                   |    Data structure in @data_uptr     |   @pt_id  |
> + * +------------------------------+-------------------------------------+-----------+
> + * | IOMMU_HWPT_TYPE_DEFAULT      |               N/A                   |    IOAS   |
> + * +------------------------------+-------------------------------------+-----------+
>    */
>   struct iommu_hwpt_alloc {
>   	__u32 size;
> @@ -369,6 +396,9 @@ struct iommu_hwpt_alloc {
>   	__u32 pt_id;
>   	__u32 out_hwpt_id;
>   	__u32 __reserved;
> +	__u32 hwpt_type;
> +	__u32 data_len;
> +	__aligned_u64 data_uptr;
>   };
>   #define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)
>