On Tue, Jun 10, 2025 at 03:13:49PM +0200, Jens Wiklander wrote:
> From: Etienne Carriere <etienne.carri...@foss.st.com>
>
> Add a userspace API to create a tee_shm object that refers to a dmabuf
> reference.
>
> Userspace registers the dmabuf file descriptor as in a tee_shm object.
> The registration is completed with a tee_shm returned file descriptor.
>
> Userspace is free to close the dmabuf file descriptor after it has been
> registered since all the resources are now held via the new tee_shm
> object.
>
> Closing the tee_shm file descriptor will eventually release all
> resources used by the tee_shm object when all references are released.
>
> The new IOCTL, TEE_IOC_SHM_REGISTER_FD, supports dmabuf references to
> physically contiguous memory buffers. Dmabuf references acquired from
> the TEE DMA-heap can be used as protected memory for Secure Video Path
> and such use cases. It depends on the TEE and the TEE driver if dmabuf
> references acquired by other means can be used.
>
> A new tee_shm flag is added to identify tee_shm objects built from a
> registered dmabuf, TEE_SHM_DMA_BUF.
>
> Signed-off-by: Etienne Carriere <etienne.carri...@foss.st.com>
> Signed-off-by: Olivier Masse <olivier.ma...@nxp.com>
> Signed-off-by: Jens Wiklander <jens.wiklan...@linaro.org>
> ---
> drivers/tee/tee_core.c | 63 +++++++++++++++++++++-
> drivers/tee/tee_private.h | 10 ++++
> drivers/tee/tee_shm.c | 106 ++++++++++++++++++++++++++++++++++++--
> include/linux/tee_core.h | 1 +
> include/linux/tee_drv.h | 10 ++++
> include/uapi/linux/tee.h | 31 +++++++++++
> 6 files changed, 217 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index 5259b8223c27..0e9d9e5872a4 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -353,11 +353,49 @@ tee_ioctl_shm_register(struct tee_context *ctx,
> return ret;
> }
>
> +static int
> +tee_ioctl_shm_register_fd(struct tee_context *ctx,
> + struct tee_ioctl_shm_register_fd_data __user *udata)
> +{
> + struct tee_ioctl_shm_register_fd_data data;
> + struct tee_shm *shm;
> + long ret;
> +
> + if (copy_from_user(&data, udata, sizeof(data)))
> + return -EFAULT;
> +
> + /* Currently no input flags are supported */
> + if (data.flags)
> + return -EINVAL;
> +
> + shm = tee_shm_register_fd(ctx, data.fd);
> + if (IS_ERR(shm))
> + return -EINVAL;
> +
> + data.id = shm->id;
> + data.flags = shm->flags;
> + data.size = shm->size;
> +
> + if (copy_to_user(udata, &data, sizeof(data)))
> + ret = -EFAULT;
> + else
> + ret = tee_shm_get_fd(shm);
> +
> + /*
> + * When user space closes the file descriptor the shared memory
> + * should be freed or if tee_shm_get_fd() failed then it will
> + * be freed immediately.
> + */
> + tee_shm_put(shm);
> + return ret;
> +}
> +
> static int param_from_user_memref(struct tee_context *ctx,
> struct tee_param_memref *memref,
> struct tee_ioctl_param *ip)
> {
> struct tee_shm *shm;
> + size_t offs = 0;
>
> /*
> * If a NULL pointer is passed to a TA in the TEE,
> @@ -388,6 +426,26 @@ static int param_from_user_memref(struct tee_context
> *ctx,
> tee_shm_put(shm);
> return -EINVAL;
> }
> +
> + if (shm->flags & TEE_SHM_DMA_BUF) {
> + struct tee_shm_dmabuf_ref *ref;
> +
> + ref = container_of(shm, struct tee_shm_dmabuf_ref, shm);
> + if (ref->parent_shm) {
> + /*
> + * The shm already has one reference to
> + * ref->parent_shm so we are clear of 0.
> + * We're getting another reference since
> + * this shm will be used in the parameter
> + * list instead of the shm we got with
> + * tee_shm_get_from_id() above.
> + */
> + refcount_inc(&ref->parent_shm->refcount);
> + tee_shm_put(shm);
> + shm = ref->parent_shm;
> + offs = ref->offset;
> + }
> + }
> } else if (ctx->cap_memref_null) {
> /* Pass NULL pointer to OP-TEE */
> shm = NULL;
> @@ -395,7 +453,7 @@ static int param_from_user_memref(struct tee_context *ctx,
> return -EINVAL;
> }
>
> - memref->shm_offs = ip->a;
> + memref->shm_offs = ip->a + offs;
> memref->size = ip->b;
> memref->shm = shm;
>
> @@ -841,6 +899,8 @@ static long tee_ioctl(struct file *filp, unsigned int
> cmd, unsigned long arg)
> return tee_ioctl_shm_alloc(ctx, uarg);
> case TEE_IOC_SHM_REGISTER:
> return tee_ioctl_shm_register(ctx, uarg);
> + case TEE_IOC_SHM_REGISTER_FD:
> + return tee_ioctl_shm_register_fd(ctx, uarg);
> case TEE_IOC_OPEN_SESSION:
> return tee_ioctl_open_session(ctx, uarg);
> case TEE_IOC_INVOKE:
> @@ -1300,3 +1360,4 @@ MODULE_AUTHOR("Linaro");
> MODULE_DESCRIPTION("TEE Driver");
> MODULE_VERSION("1.0");
> MODULE_LICENSE("GPL v2");
> +MODULE_IMPORT_NS("DMA_BUF");
> diff --git a/drivers/tee/tee_private.h b/drivers/tee/tee_private.h
> index 6c6ff5d5eed2..308467705da6 100644
> --- a/drivers/tee/tee_private.h
> +++ b/drivers/tee/tee_private.h
> @@ -13,6 +13,16 @@
> #include <linux/mutex.h>
> #include <linux/types.h>
>
> +/* extra references appended to shm object for registered shared memory */
> +struct tee_shm_dmabuf_ref {
> + struct tee_shm shm;
> + size_t offset;
> + struct dma_buf *dmabuf;
> + struct dma_buf_attachment *attach;
> + struct sg_table *sgt;
> + struct tee_shm *parent_shm;
> +};
> +
> int tee_shm_get_fd(struct tee_shm *shm);
>
> bool tee_device_get(struct tee_device *teedev);
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index daf6e5cfd59a..e63095e84644 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -4,6 +4,7 @@
> */
> #include <linux/anon_inodes.h>
> #include <linux/device.h>
> +#include <linux/dma-buf.h>
> #include <linux/idr.h>
> #include <linux/io.h>
> #include <linux/mm.h>
> @@ -45,7 +46,21 @@ static void release_registered_pages(struct tee_shm *shm)
>
> static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
> {
> - if (shm->flags & TEE_SHM_POOL) {
> + void *p = shm;
> +
> + if (shm->flags & TEE_SHM_DMA_BUF) {
> + struct tee_shm_dmabuf_ref *ref;
> +
> + ref = container_of(shm, struct tee_shm_dmabuf_ref, shm);
> + p = ref;
> + if (ref->attach) {
> + dma_buf_unmap_attachment(ref->attach, ref->sgt,
> + DMA_BIDIRECTIONAL);
> +
> + dma_buf_detach(ref->dmabuf, ref->attach);
> + }
> + dma_buf_put(ref->dmabuf);
> + } else if (shm->flags & TEE_SHM_POOL) {
> teedev->pool->ops->free(teedev->pool, shm);
> } else if (shm->flags & TEE_SHM_DYNAMIC) {
> int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
> @@ -59,7 +74,7 @@ static void tee_shm_release(struct tee_device *teedev,
> struct tee_shm *shm)
>
> teedev_ctx_put(shm->ctx);
>
> - kfree(shm);
> + kfree(p);
>
> tee_device_put(teedev);
> }
> @@ -169,7 +184,7 @@ struct tee_shm *tee_shm_alloc_user_buf(struct tee_context
> *ctx, size_t size)
> * tee_client_invoke_func(). The memory allocated is later freed with a
> * call to tee_shm_free().
> *
> - * @returns a pointer to 'struct tee_shm'
> + * @returns a pointer to 'struct tee_shm' on success, and ERR_PTR on failure
> */
> struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t
> size)
> {
> @@ -179,6 +194,91 @@ struct tee_shm *tee_shm_alloc_kernel_buf(struct
> tee_context *ctx, size_t size)
> }
> EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf);
>
> +struct tee_shm *tee_shm_register_fd(struct tee_context *ctx, int fd)
> +{
> + struct tee_shm_dmabuf_ref *ref;
> + int rc;
> +
> + if (!tee_device_get(ctx->teedev))
> + return ERR_PTR(-EINVAL);
> +
> + teedev_ctx_get(ctx);
> +
> + ref = kzalloc(sizeof(*ref), GFP_KERNEL);
> + if (!ref) {
> + rc = -ENOMEM;
> + goto err_put_tee;
> + }
> +
> + refcount_set(&ref->shm.refcount, 1);
> + ref->shm.ctx = ctx;
> + ref->shm.id = -1;
> + ref->shm.flags = TEE_SHM_DMA_BUF;
> +
> + ref->dmabuf = dma_buf_get(fd);
> + if (IS_ERR(ref->dmabuf)) {
> + rc = PTR_ERR(ref->dmabuf);
> + goto err_kfree_ref;
> + }
> +
> + rc = tee_heap_update_from_dma_buf(ctx->teedev, ref->dmabuf,
> + &ref->offset, &ref->shm,
> + &ref->parent_shm);
> + if (!rc)
> + goto out;
One odd thing I find here, why do we bail out on success case here?
Don't we need the DMA buffer attach and map APIs to be invoked on
success case here?
-Sumit
> + if (rc != -EINVAL)
> + goto err_put_dmabuf;
> +
> + ref->attach = dma_buf_attach(ref->dmabuf, &ctx->teedev->dev);
> + if (IS_ERR(ref->attach)) {
> + rc = PTR_ERR(ref->attach);
> + goto err_put_dmabuf;
> + }
> +
> + ref->sgt = dma_buf_map_attachment(ref->attach, DMA_BIDIRECTIONAL);
> + if (IS_ERR(ref->sgt)) {
> + rc = PTR_ERR(ref->sgt);
> + goto err_detach;
> + }
> +
> + if (sg_nents(ref->sgt->sgl) != 1) {
> + rc = -EINVAL;
> + goto err_unmap_attachement;
> + }
> +
> + ref->shm.paddr = page_to_phys(sg_page(ref->sgt->sgl));
> + ref->shm.size = ref->sgt->sgl->length;
> +
> +out:
> + mutex_lock(&ref->shm.ctx->teedev->mutex);
> + ref->shm.id = idr_alloc(&ref->shm.ctx->teedev->idr, &ref->shm,
> + 1, 0, GFP_KERNEL);
> + mutex_unlock(&ref->shm.ctx->teedev->mutex);
> + if (ref->shm.id < 0) {
> + rc = ref->shm.id;
> + if (ref->attach)
> + goto err_unmap_attachement;
> + goto err_put_dmabuf;
> + }
> +
> + return &ref->shm;
> +
> +err_unmap_attachement:
> + dma_buf_unmap_attachment(ref->attach, ref->sgt, DMA_BIDIRECTIONAL);
> +err_detach:
> + dma_buf_detach(ref->dmabuf, ref->attach);
> +err_put_dmabuf:
> + dma_buf_put(ref->dmabuf);
> +err_kfree_ref:
> + kfree(ref);
> +err_put_tee:
> + teedev_ctx_put(ctx);
> + tee_device_put(ctx->teedev);
> +
> + return ERR_PTR(rc);
> +}
> +EXPORT_SYMBOL_GPL(tee_shm_register_fd);
> +
> /**
> * tee_shm_alloc_priv_buf() - Allocate shared memory for a privately shared
> * kernel buffer
> diff --git a/include/linux/tee_core.h b/include/linux/tee_core.h
> index 22e03d897dc3..f17710196c4c 100644
> --- a/include/linux/tee_core.h
> +++ b/include/linux/tee_core.h
> @@ -28,6 +28,7 @@
> #define TEE_SHM_USER_MAPPED BIT(1) /* Memory mapped in user space */
> #define TEE_SHM_POOL BIT(2) /* Memory allocated from pool */
> #define TEE_SHM_PRIV BIT(3) /* Memory private to TEE driver */
> +#define TEE_SHM_DMA_BUF BIT(4) /* Memory with dma-buf handle */
>
> #define TEE_DEVICE_FLAG_REGISTERED 0x1
> #define TEE_MAX_DEV_NAME_LEN 32
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index a54c203000ed..824f1251de60 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -116,6 +116,16 @@ struct tee_shm *tee_shm_alloc_kernel_buf(struct
> tee_context *ctx, size_t size);
> struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
> void *addr, size_t length);
>
> +/**
> + * tee_shm_register_fd() - Register shared memory from file descriptor
> + *
> + * @ctx: Context that allocates the shared memory
> + * @fd: Shared memory file descriptor reference
> + *
> + * @returns a pointer to 'struct tee_shm' on success, and ERR_PTR on failure
> + */
> +struct tee_shm *tee_shm_register_fd(struct tee_context *ctx, int fd);
> +
> /**
> * tee_shm_free() - Free shared memory
> * @shm: Handle to shared memory to free
> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
> index d0430bee8292..d843cf980d98 100644
> --- a/include/uapi/linux/tee.h
> +++ b/include/uapi/linux/tee.h
> @@ -378,6 +378,37 @@ struct tee_ioctl_shm_register_data {
> __s32 id;
> };
>
> +/**
> + * struct tee_ioctl_shm_register_fd_data - Shared memory registering argument
> + * @fd: [in] File descriptor identifying dmabuf reference
> + * @size: [out] Size of referenced memory
> + * @flags: [in] Flags to/from allocation.
> + * @id: [out] Identifier of the shared memory
> + *
> + * The flags field should currently be zero as input. Updated by the call
> + * with actual flags as defined by TEE_IOCTL_SHM_* above.
> + * This structure is used as argument for TEE_IOC_SHM_REGISTER_FD below.
> + */
> +struct tee_ioctl_shm_register_fd_data {
> + __s64 fd;
> + __u64 size;
> + __u32 flags;
> + __s32 id;
> +};
> +
> +/**
> + * TEE_IOC_SHM_REGISTER_FD - register a shared memory from a file descriptor
> + *
> + * Returns a file descriptor on success or < 0 on failure
> + *
> + * The returned file descriptor refers to the shared memory object in the
> + * kernel. The supplied file deccriptor can be closed if it's not needed
> + * for other purposes. The shared memory is freed when the descriptor is
> + * closed.
> + */
> +#define TEE_IOC_SHM_REGISTER_FD _IOWR(TEE_IOC_MAGIC, TEE_IOC_BASE + 8, \
> + struct tee_ioctl_shm_register_fd_data)
> +
> /**
> * TEE_IOC_SHM_REGISTER - Register shared memory argument
> *
> --
> 2.43.0
>
