Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE

On 2023/11/17 21:07, Yi Liu wrote:

In nested translation, the stage-1 page table is user-managed but cached by the IOMMU hardware, so an update on present page table entries in the stage-1 page table should be followed with a cache invalidation.

Add an IOMMU_HWPT_INVALIDATE ioctl to support such a cache invalidation. It takes hwpt_id to specify the iommu_domain, and a multi-entry array to support multiple invalidation requests in one ioctl.

Check cache_invalidate_user op in the iommufd_hw_pagetable_alloc_nested, since all nested domains need that.

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 | 35 +++++++++++++++++++++++++ drivers/iommu/iommufd/iommufd_private.h | 9 +++++++ drivers/iommu/iommufd/main.c | 3 +++ include/uapi/linux/iommufd.h | 35 +++++++++++++++++++++++++ 4 files changed, 82 insertions(+)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index 2abbeafdbd22..367459d92f69 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -238,6 +238,11 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx, rc = -EINVAL; goto out_abort; }

• /* Driver is buggy by missing cache_invalidate_user in domain_ops */
• if (WARN_ON_ONCE(!hwpt->domain->ops->cache_invalidate_user)) {

• rc = -EINVAL;
  

• goto out_abort;
  

• } return hwpt_nested;

out_abort: @@ -370,4 +375,34 @@ int iommufd_hwpt_get_dirty_bitmap(struct iommufd_ucmd *ucmd) iommufd_put_object(&hwpt_paging->common.obj); return rc; +};

+int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd) +{

• struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
• struct iommu_user_data_array data_array = {

• .type = cmd->req_type,
  

• .uptr = u64_to_user_ptr(cmd->reqs_uptr),
  

• .entry_len = cmd->req_len,
  

• .entry_num = cmd->req_num,
  

• };
• struct iommufd_hw_pagetable *hwpt;
• int rc = 0;
• if (cmd->req_type == IOMMU_HWPT_DATA_NONE)

• return -EINVAL;
  

• if (!cmd->reqs_uptr || !cmd->req_len || !cmd->req_num)

• return -EINVAL;
  

• hwpt = iommufd_hw_pagetable_get_nested(ucmd, cmd->hwpt_id);
• if (IS_ERR(hwpt))

• return PTR_ERR(hwpt);
  

• rc = hwpt->domain->ops->cache_invalidate_user(hwpt->domain, &data_array,

• 				      &cmd->out_driver_error_code);
  

• cmd->req_num = data_array.entry_num;
• if (iommufd_ucmd_respond(ucmd, sizeof(*cmd)))

• return -EFAULT;
  

• iommufd_put_object(&hwpt->obj);
• return rc; }

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index a74cfefffbc6..160521800d9b 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -301,6 +301,7 @@ void iommufd_hwpt_paging_abort(struct iommufd_object *obj); void iommufd_hwpt_nested_destroy(struct iommufd_object *obj); void iommufd_hwpt_nested_abort(struct iommufd_object *obj); int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd); +int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd); static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx, struct iommufd_hw_pagetable *hwpt) @@ -318,6 +319,14 @@ static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx, refcount_dec(&hwpt->obj.users); } +static inline struct iommufd_hw_pagetable * +iommufd_hw_pagetable_get_nested(struct iommufd_ucmd *ucmd, u32 id) +{

• return container_of(iommufd_get_object(ucmd->ictx, id,

• 			       IOMMUFD_OBJ_HWPT_NESTED),
  

• 	    struct iommufd_hw_pagetable, obj);
  

+}

• struct iommufd_group { struct kref ref; struct mutex lock;

diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 45b9d40773b1..6edef860f91c 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -309,6 +309,7 @@ union ucmd_buffer { struct iommu_hwpt_alloc hwpt; struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap; struct iommu_hwpt_set_dirty_tracking set_dirty_tracking;

• struct iommu_hwpt_invalidate cache; struct iommu_ioas_alloc alloc; struct iommu_ioas_allow_iovas allow_iovas; struct iommu_ioas_copy ioas_copy;

@@ -348,6 +349,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = { struct iommu_hwpt_get_dirty_bitmap, data), IOCTL_OP(IOMMU_HWPT_SET_DIRTY_TRACKING, iommufd_hwpt_set_dirty_tracking, struct iommu_hwpt_set_dirty_tracking, __reserved),

• IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,

•  struct iommu_hwpt_invalidate, out_driver_error_code),
  

  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 0b2bc6252e2c..7f92cecc87d7 100644 --- a/include/uapi/linux/iommufd.h +++ b/include/uapi/linux/iommufd.h @@ -49,6 +49,7 @@ enum { IOMMUFD_CMD_GET_HW_INFO, IOMMUFD_CMD_HWPT_SET_DIRTY_TRACKING, IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP,

• IOMMUFD_CMD_HWPT_INVALIDATE, };

/** @@ -613,4 +614,38 @@ struct iommu_hwpt_get_dirty_bitmap { #define IOMMU_HWPT_GET_DIRTY_BITMAP _IO(IOMMUFD_TYPE, \ IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP) +/**

• • struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
• • @size: sizeof(struct iommu_hwpt_invalidate)
• • @hwpt_id: HWPT ID of a nested HWPT for cache invalidation
• • @reqs_uptr: User pointer to an array having @req_num of cache invalidation

• •         requests. The request entries in the array are of fixed width
    

• •         @req_len, and contain a user data structure for invalidation
    

• •         request specific to the given hardware page table.
    

• • @req_type: One of enum iommu_hwpt_data_type, defining the data type of all

• •        the entries in the invalidation request array. It should suit
    

• •        with the data_type passed per the allocation of the hwpt pointed
    

• •        by @hwpt_id.
    

@Jason and Kevin,

Here a check with you two. I had a conversation with Nic on the definition of req_type here. It was added to support potential multiple kinds of cache invalidation data types for a invalidating cache for a single hwpt type[1]. But we defined it as reusing the hwpt_data_type. In this way, it is not able to support the potential case in[1]. is it? Shall we define a separate enum for invalidation data types? And how can we let user know the available invalidation data types for a hwpt type? Any idea?

[1] https://lore.kernel.org/linux-iommu/20231018163720.GA3952@nvidia.com/

• • @req_len: Length (in bytes) of a request entry in the request array
• • @req_num: Input the number of cache invalidation requests in the array.

• •       Output the number of requests successfully handled by kernel.
    

• • @out_driver_error_code: Report a driver speicifc error code upon failure.

• •                     It's optional, driver has a choice to fill it or
    

• •                     not.
    

• • Invalidate the iommu cache for user-managed page table. Modifications on a
• • user-managed page table should be followed by this operation to sync cache.
• • Each ioctl can support one or more cache invalidation requests in the array
• • that has a total size of @req_len * @req_num.
• */

+struct iommu_hwpt_invalidate {

• __u32 size;
• __u32 hwpt_id;
• __aligned_u64 reqs_uptr;
• __u32 req_type;
• __u32 req_len;
• __u32 req_num;
• __u32 out_driver_error_code;

+}; +#define IOMMU_HWPT_INVALIDATE _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_INVALIDATE) #endif