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

Liu, Jingqi
2023-05-17T03:08:39Z

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)
>