Re: [PATCH v6 09/10] optee: FF-A: dynamic restricted memory allocation

Sumit Garg
2025-03-25T07:42:00Z

On Wed, Mar 05, 2025 at 02:04:15PM +0100, Jens Wiklander wrote:
> Add support in the OP-TEE backend driver dynamic restricted memory
> allocation with FF-A.
>
> The restricted memory pools for dynamically allocated restrict memory
> are instantiated when requested by user-space. This instantiation can
> fail if OP-TEE doesn't support the requested use-case of restricted
> memory.
>
> Restricted memory pools based on a static carveout or dynamic allocation
> can coexist for different use-cases. We use only dynamic allocation with
> FF-A.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
> ---
> drivers/tee/optee/Makefile | 1 +
> drivers/tee/optee/ffa_abi.c | 143 ++++++++++++-
> drivers/tee/optee/optee_private.h | 13 +-
> drivers/tee/optee/rstmem.c | 329 ++++++++++++++++++++++++++++++
> 4 files changed, 483 insertions(+), 3 deletions(-)
> create mode 100644 drivers/tee/optee/rstmem.c
>
> diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
> index a6eff388d300..498969fb8e40 100644
> --- a/drivers/tee/optee/Makefile
> +++ b/drivers/tee/optee/Makefile
> @@ -4,6 +4,7 @@ optee-objs += core.o
> optee-objs += call.o
> optee-objs += notif.o
> optee-objs += rpc.o
> +optee-objs += rstmem.o
> optee-objs += supp.o
> optee-objs += device.o
> optee-objs += smc_abi.o
> diff --git a/drivers/tee/optee/ffa_abi.c b/drivers/tee/optee/ffa_abi.c
> index e4b08cd195f3..6a55114232ef 100644
> --- a/drivers/tee/optee/ffa_abi.c
> +++ b/drivers/tee/optee/ffa_abi.c
> @@ -672,6 +672,123 @@ static int optee_ffa_do_call_with_arg(struct tee_context *ctx,
> return optee_ffa_yielding_call(ctx, &data, rpc_arg, system_thread);
> }
>
> +static int do_call_lend_rstmem(struct optee *optee, u64 cookie, u32 use_case)
> +{
> + struct optee_shm_arg_entry *entry;
> + struct optee_msg_arg *msg_arg;
> + struct tee_shm *shm;
> + u_int offs;
> + int rc;
> +
> + msg_arg = optee_get_msg_arg(optee->ctx, 1, &entry, &shm, &offs);
> + if (IS_ERR(msg_arg))
> + return PTR_ERR(msg_arg);
> +
> + msg_arg->cmd = OPTEE_MSG_CMD_ASSIGN_RSTMEM;
> + msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT;
> + msg_arg->params[0].u.value.a = cookie;
> + msg_arg->params[0].u.value.b = use_case;
> +
> + rc = optee->ops->do_call_with_arg(optee->ctx, shm, offs, false);
> + if (rc)
> + goto out;
> + if (msg_arg->ret != TEEC_SUCCESS) {
> + rc = -EINVAL;
> + goto out;
> + }
> +
> +out:
> + optee_free_msg_arg(optee->ctx, entry, offs);
> + return rc;
> +}
> +
> +static int optee_ffa_lend_rstmem(struct optee *optee, struct tee_shm *rstmem,
> + u16 *end_points, unsigned int ep_count,
> + u32 use_case)
> +{
> + struct ffa_device *ffa_dev = optee->ffa.ffa_dev;
> + const struct ffa_mem_ops *mem_ops = ffa_dev->ops->mem_ops;
> + const struct ffa_msg_ops *msg_ops = ffa_dev->ops->msg_ops;
> + struct ffa_send_direct_data data;
> + struct ffa_mem_region_attributes *mem_attr;
> + struct ffa_mem_ops_args args = {
> + .use_txbuf = true,
> + .tag = use_case,
> + };
> + struct page *page;
> + struct scatterlist sgl;
> + unsigned int n;
> + int rc;
> +
> + mem_attr = kcalloc(ep_count, sizeof(*mem_attr), GFP_KERNEL);
> + for (n = 0; n < ep_count; n++) {
> + mem_attr[n].receiver = end_points[n];
> + mem_attr[n].attrs = FFA_MEM_RW;
> + }
> + args.attrs = mem_attr;
> + args.nattrs = ep_count;
> +
> + page = phys_to_page(rstmem->paddr);
> + sg_init_table(&sgl, 1);
> + sg_set_page(&sgl, page, rstmem->size, 0);
> +
> + args.sg = &sgl;
> + rc = mem_ops->memory_lend(&args);
> + kfree(mem_attr);
> + if (rc)
> + return rc;
> +
> + rc = do_call_lend_rstmem(optee, args.g_handle, use_case);
> + if (rc)
> + goto err_reclaim;
> +
> + rc = optee_shm_add_ffa_handle(optee, rstmem, args.g_handle);
> + if (rc)
> + goto err_unreg;
> +
> + rstmem->sec_world_id = args.g_handle;
> +
> + return 0;
> +
> +err_unreg:
> + data = (struct ffa_send_direct_data){
> + .data0 = OPTEE_FFA_RELEASE_RSTMEM,
> + .data1 = (u32)args.g_handle,
> + .data2 = (u32)(args.g_handle >> 32),
> + };
> + msg_ops->sync_send_receive(ffa_dev, &data);
> +err_reclaim:
> + mem_ops->memory_reclaim(args.g_handle, 0);
> + return rc;
> +}
> +
> +static int optee_ffa_reclaim_rstmem(struct optee *optee, struct tee_shm *rstmem)
> +{
> + struct ffa_device *ffa_dev = optee->ffa.ffa_dev;
> + const struct ffa_msg_ops *msg_ops = ffa_dev->ops->msg_ops;
> + const struct ffa_mem_ops *mem_ops = ffa_dev->ops->mem_ops;
> + u64 global_handle = rstmem->sec_world_id;
> + struct ffa_send_direct_data data = {
> + .data0 = OPTEE_FFA_RELEASE_RSTMEM,
> + .data1 = (u32)global_handle,
> + .data2 = (u32)(global_handle >> 32)
> + };
> + int rc;
> +
> + optee_shm_rem_ffa_handle(optee, global_handle);
> + rstmem->sec_world_id = 0;
> +
> + rc = msg_ops->sync_send_receive(ffa_dev, &data);
> + if (rc)
> + pr_err("Release SHM id 0x%llx rc %d\n", global_handle, rc);
> +
> + rc = mem_ops->memory_reclaim(global_handle, 0);
> + if (rc)
> + pr_err("mem_reclaim: 0x%llx %d", global_handle, rc);
> +
> + return rc;
> +}
> +
> /*
> * 6. Driver initialization
> *
> @@ -833,6 +950,8 @@ static const struct optee_ops optee_ffa_ops = {
> .do_call_with_arg = optee_ffa_do_call_with_arg,
> .to_msg_param = optee_ffa_to_msg_param,
> .from_msg_param = optee_ffa_from_msg_param,
> + .lend_rstmem = optee_ffa_lend_rstmem,
> + .reclaim_rstmem = optee_ffa_reclaim_rstmem,
> };
>
> static void optee_ffa_remove(struct ffa_device *ffa_dev)
> @@ -941,7 +1060,7 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> optee->pool, optee);
> if (IS_ERR(teedev)) {
> rc = PTR_ERR(teedev);
> - goto err_free_pool;
> + goto err_free_shm_pool;
> }
> optee->teedev = teedev;
>
> @@ -988,6 +1107,24 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> rc);
> }
>
> + if (IS_ENABLED(CONFIG_CMA) && !IS_MODULE(CONFIG_OPTEE) &&

The CMA dependency should be managed via Kconfig.

> + (sec_caps & OPTEE_FFA_SEC_CAP_RSTMEM)) {
> + enum tee_dma_heap_id id = TEE_DMA_HEAP_SECURE_VIDEO_PLAY;
> + struct tee_rstmem_pool *pool;
> +
> + pool = optee_rstmem_alloc_cma_pool(optee, id);
> + if (IS_ERR(pool)) {
> + rc = PTR_ERR(pool);
> + goto err_notif_uninit;
> + }
> +
> + rc = tee_device_register_dma_heap(optee->teedev, id, pool);
> + if (rc) {
> + pool->ops->destroy_pool(pool);
> + goto err_notif_uninit;
> + }
> + }
> +
> rc = optee_enumerate_devices(PTA_CMD_GET_DEVICES);
> if (rc)
> goto err_unregister_devices;
> @@ -1001,6 +1138,8 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
>
> err_unregister_devices:
> optee_unregister_devices();
> + tee_device_unregister_all_dma_heaps(optee->teedev);
> +err_notif_uninit:
> if (optee->ffa.bottom_half_value != U32_MAX)
> notif_ops->notify_relinquish(ffa_dev,
> optee->ffa.bottom_half_value);
> @@ -1018,7 +1157,7 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> tee_device_unregister(optee->supp_teedev);
> err_unreg_teedev:
> tee_device_unregister(optee->teedev);
> -err_free_pool:
> +err_free_shm_pool:
> tee_shm_pool_free(pool);
> err_free_optee:
> kfree(optee);
> diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
> index 20eda508dbac..faab31ad7c52 100644
> --- a/drivers/tee/optee/optee_private.h
> +++ b/drivers/tee/optee/optee_private.h
> @@ -174,9 +174,14 @@ struct optee;
> * @do_call_with_arg: enters OP-TEE in secure world
> * @to_msg_param: converts from struct tee_param to OPTEE_MSG parameters
> * @from_msg_param: converts from OPTEE_MSG parameters to struct tee_param
> + * @lend_rstmem: lends physically contiguous memory as restricted
> + * memory, inaccessible by the kernel
> + * @reclaim_rstmem: reclaims restricted memory previously lent with
> + * @lend_rstmem() and makes it accessible by the
> + * kernel again
> *
> * These OPs are only supposed to be used internally in the OP-TEE driver
> - * as a way of abstracting the different methogs of entering OP-TEE in
> + * as a way of abstracting the different methods of entering OP-TEE in
> * secure world.
> */
> struct optee_ops {
> @@ -191,6 +196,10 @@ struct optee_ops {
> size_t num_params,
> const struct optee_msg_param *msg_params,
> bool update_out);
> + int (*lend_rstmem)(struct optee *optee, struct tee_shm *rstmem,
> + u16 *end_points, unsigned int ep_count,
> + u32 use_case);
> + int (*reclaim_rstmem)(struct optee *optee, struct tee_shm *rstmem);
> };
>
> /**
> @@ -285,6 +294,8 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params,
> void optee_supp_init(struct optee_supp *supp);
> void optee_supp_uninit(struct optee_supp *supp);
> void optee_supp_release(struct optee_supp *supp);
> +struct tee_rstmem_pool *optee_rstmem_alloc_cma_pool(struct optee *optee,
> + enum tee_dma_heap_id id);
>
> int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params,
> struct tee_param *param);
> diff --git a/drivers/tee/optee/rstmem.c b/drivers/tee/optee/rstmem.c
> new file mode 100644
> index 000000000000..ea27769934d4
> --- /dev/null
> +++ b/drivers/tee/optee/rstmem.c
> @@ -0,0 +1,329 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025, Linaro Limited
> + */
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/errno.h>
> +#include <linux/genalloc.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/tee_core.h>
> +#include <linux/types.h>
> +#include "optee_private.h"
> +
> +struct optee_rstmem_cma_pool {
> + struct tee_rstmem_pool pool;
> + struct gen_pool *gen_pool;
> + struct optee *optee;
> + size_t page_count;
> + u16 *end_points;
> + u_int end_point_count;
> + u_int align;
> + refcount_t refcount;
> + u32 use_case;
> + struct tee_shm *rstmem;
> + /* Protects when initializing and tearing down this struct */
> + struct mutex mutex;
> +};
> +
> +static struct optee_rstmem_cma_pool *
> +to_rstmem_cma_pool(struct tee_rstmem_pool *pool)
> +{
> + return container_of(pool, struct optee_rstmem_cma_pool, pool);
> +}
> +
> +static int init_cma_rstmem(struct optee_rstmem_cma_pool *rp)
> +{
> + int rc;
> +
> + rp->rstmem = tee_shm_alloc_cma_phys_mem(rp->optee->ctx, rp->page_count,
> + rp->align);
> + if (IS_ERR(rp->rstmem)) {
> + rc = PTR_ERR(rp->rstmem);
> + goto err_null_rstmem;
> + }
> +
> + /*
> + * TODO unmap the memory range since the physical memory will
> + * become inaccesible after the lend_rstmem() call.
> + */

What's your plan for this TODO? I think we need a CMA allocator here
which can allocate un-mapped memory such that any cache speculation
won't lead to CPU hangs once the memory restriction comes into picture.

> + rc = rp->optee->ops->lend_rstmem(rp->optee, rp->rstmem, rp->end_points,
> + rp->end_point_count, rp->use_case);
> + if (rc)
> + goto err_put_shm;
> + rp->rstmem->flags |= TEE_SHM_DYNAMIC;
> +
> + rp->gen_pool = gen_pool_create(PAGE_SHIFT, -1);
> + if (!rp->gen_pool) {
> + rc = -ENOMEM;
> + goto err_reclaim;
> + }
> +
> + rc = gen_pool_add(rp->gen_pool, rp->rstmem->paddr,
> + rp->rstmem->size, -1);
> + if (rc)
> + goto err_free_pool;
> +
> + refcount_set(&rp->refcount, 1);
> + return 0;
> +
> +err_free_pool:
> + gen_pool_destroy(rp->gen_pool);
> + rp->gen_pool = NULL;
> +err_reclaim:
> + rp->optee->ops->reclaim_rstmem(rp->optee, rp->rstmem);
> +err_put_shm:
> + tee_shm_put(rp->rstmem);
> +err_null_rstmem:
> + rp->rstmem = NULL;
> + return rc;
> +}
> +
> +static int get_cma_rstmem(struct optee_rstmem_cma_pool *rp)
> +{
> + int rc = 0;
> +
> + if (!refcount_inc_not_zero(&rp->refcount)) {
> + mutex_lock(&rp->mutex);
> + if (rp->gen_pool) {
> + /*
> + * Another thread has already initialized the pool
> + * before us, or the pool was just about to be torn
> + * down. Either way we only need to increase the
> + * refcount and we're done.
> + */
> + refcount_inc(&rp->refcount);
> + } else {
> + rc = init_cma_rstmem(rp);
> + }
> + mutex_unlock(&rp->mutex);
> + }
> +
> + return rc;
> +}
> +
> +static void release_cma_rstmem(struct optee_rstmem_cma_pool *rp)
> +{
> + gen_pool_destroy(rp->gen_pool);
> + rp->gen_pool = NULL;
> +
> + rp->optee->ops->reclaim_rstmem(rp->optee, rp->rstmem);
> + rp->rstmem->flags &= ~TEE_SHM_DYNAMIC;
> +
> + WARN(refcount_read(&rp->rstmem->refcount) != 1, "Unexpected refcount");
> + tee_shm_put(rp->rstmem);
> + rp->rstmem = NULL;
> +}
> +
> +static void put_cma_rstmem(struct optee_rstmem_cma_pool *rp)
> +{
> + if (refcount_dec_and_test(&rp->refcount)) {
> + mutex_lock(&rp->mutex);
> + if (rp->gen_pool)
> + release_cma_rstmem(rp);
> + mutex_unlock(&rp->mutex);
> + }
> +}
> +
> +static int rstmem_pool_op_cma_alloc(struct tee_rstmem_pool *pool,
> + struct sg_table *sgt, size_t size,
> + size_t *offs)
> +{
> + struct optee_rstmem_cma_pool *rp = to_rstmem_cma_pool(pool);
> + size_t sz = ALIGN(size, PAGE_SIZE);
> + phys_addr_t pa;
> + int rc;
> +
> + rc = get_cma_rstmem(rp);
> + if (rc)
> + return rc;
> +
> + pa = gen_pool_alloc(rp->gen_pool, sz);
> + if (!pa) {
> + rc = -ENOMEM;
> + goto err_put;
> + }
> +
> + rc = sg_alloc_table(sgt, 1, GFP_KERNEL);
> + if (rc)
> + goto err_free;
> +
> + sg_set_page(sgt->sgl, phys_to_page(pa), size, 0);
> + *offs = pa - rp->rstmem->paddr;
> +
> + return 0;
> +err_free:
> + gen_pool_free(rp->gen_pool, pa, size);
> +err_put:
> + put_cma_rstmem(rp);
> +
> + return rc;
> +}
> +
> +static void rstmem_pool_op_cma_free(struct tee_rstmem_pool *pool,
> + struct sg_table *sgt)
> +{
> + struct optee_rstmem_cma_pool *rp = to_rstmem_cma_pool(pool);
> + struct scatterlist *sg;
> + int i;
> +
> + for_each_sgtable_sg(sgt, sg, i)
> + gen_pool_free(rp->gen_pool, sg_phys(sg), sg->length);
> + sg_free_table(sgt);
> + put_cma_rstmem(rp);
> +}
> +
> +static int rstmem_pool_op_cma_update_shm(struct tee_rstmem_pool *pool,
> + struct sg_table *sgt, size_t offs,
> + struct tee_shm *shm,
> + struct tee_shm **parent_shm)
> +{
> + struct optee_rstmem_cma_pool *rp = to_rstmem_cma_pool(pool);
> +
> + *parent_shm = rp->rstmem;
> +
> + return 0;
> +}
> +
> +static void pool_op_cma_destroy_pool(struct tee_rstmem_pool *pool)
> +{
> + struct optee_rstmem_cma_pool *rp = to_rstmem_cma_pool(pool);
> +
> + mutex_destroy(&rp->mutex);
> + kfree(rp);
> +}
> +
> +static struct tee_rstmem_pool_ops rstmem_pool_ops_cma = {
> + .alloc = rstmem_pool_op_cma_alloc,
> + .free = rstmem_pool_op_cma_free,
> + .update_shm = rstmem_pool_op_cma_update_shm,
> + .destroy_pool = pool_op_cma_destroy_pool,
> +};
> +
> +static int get_rstmem_config(struct optee *optee, u32 use_case,
> + size_t *min_size, u_int *min_align,
> + u16 *end_points, u_int *ep_count)

I guess this end points terminology is specific to FF-A ABI. Is there
any relevance for this in the common APIs?

-Sumit

> +{
> + struct tee_param params[2] = {
> + [0] = {
> + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT,
> + .u.value.a = use_case,
> + },
> + [1] = {
> + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT,
> + },
> + };
> + struct optee_shm_arg_entry *entry;
> + struct tee_shm *shm_param = NULL;
> + struct optee_msg_arg *msg_arg;
> + struct tee_shm *shm;
> + u_int offs;
> + int rc;
> +
> + if (end_points && *ep_count) {
> + params[1].u.memref.size = *ep_count * sizeof(*end_points);
> + shm_param = tee_shm_alloc_priv_buf(optee->ctx,
> + params[1].u.memref.size);
> + if (IS_ERR(shm_param))
> + return PTR_ERR(shm_param);
> + params[1].u.memref.shm = shm_param;
> + }
> +
> + msg_arg = optee_get_msg_arg(optee->ctx, ARRAY_SIZE(params), &entry,
> + &shm, &offs);
> + if (IS_ERR(msg_arg)) {
> + rc = PTR_ERR(msg_arg);
> + goto out_free_shm;
> + }
> + msg_arg->cmd = OPTEE_MSG_CMD_GET_RSTMEM_CONFIG;
> +
> + rc = optee->ops->to_msg_param(optee, msg_arg->params,
> + ARRAY_SIZE(params), params,
> + false /*!update_out*/);
> + if (rc)
> + goto out_free_msg;
> +
> + rc = optee->ops->do_call_with_arg(optee->ctx, shm, offs, false);
> + if (rc)
> + goto out_free_msg;
> + if (msg_arg->ret && msg_arg->ret != TEEC_ERROR_SHORT_BUFFER) {
> + rc = -EINVAL;
> + goto out_free_msg;
> + }
> +
> + rc = optee->ops->from_msg_param(optee, params, ARRAY_SIZE(params),
> + msg_arg->params, true /*update_out*/);
> + if (rc)
> + goto out_free_msg;
> +
> + if (!msg_arg->ret && end_points &&
> + *ep_count < params[1].u.memref.size / sizeof(u16)) {
> + rc = -EINVAL;
> + goto out_free_msg;
> + }
> +
> + *min_size = params[0].u.value.a;
> + *min_align = params[0].u.value.b;
> + *ep_count = params[1].u.memref.size / sizeof(u16);
> +
> + if (msg_arg->ret == TEEC_ERROR_SHORT_BUFFER) {
> + rc = -ENOSPC;
> + goto out_free_msg;
> + }
> +
> + if (end_points)
> + memcpy(end_points, tee_shm_get_va(shm_param, 0),
> + params[1].u.memref.size);
> +
> +out_free_msg:
> + optee_free_msg_arg(optee->ctx, entry, offs);
> +out_free_shm:
> + if (shm_param)
> + tee_shm_free(shm_param);
> + return rc;
> +}
> +
> +struct tee_rstmem_pool *optee_rstmem_alloc_cma_pool(struct optee *optee,
> + enum tee_dma_heap_id id)
> +{
> + struct optee_rstmem_cma_pool *rp;
> + u32 use_case = id;
> + size_t min_size;
> + int rc;
> +
> + rp = kzalloc(sizeof(*rp), GFP_KERNEL);
> + if (!rp)
> + return ERR_PTR(-ENOMEM);
> + rp->use_case = use_case;
> +
> + rc = get_rstmem_config(optee, use_case, &min_size, &rp->align, NULL,
> + &rp->end_point_count);
> + if (rc) {
> + if (rc != -ENOSPC)
> + goto err;
> + rp->end_points = kcalloc(rp->end_point_count,
> + sizeof(*rp->end_points), GFP_KERNEL);
> + if (!rp->end_points) {
> + rc = -ENOMEM;
> + goto err;
> + }
> + rc = get_rstmem_config(optee, use_case, &min_size, &rp->align,
> + rp->end_points, &rp->end_point_count);
> + if (rc)
> + goto err_kfree_eps;
> + }
> +
> + rp->pool.ops = &rstmem_pool_ops_cma;
> + rp->optee = optee;
> + rp->page_count = min_size / PAGE_SIZE;
> + mutex_init(&rp->mutex);
> +
> + return &rp->pool;
> +
> +err_kfree_eps:
> + kfree(rp->end_points);
> +err:
> + kfree(rp);
> + return ERR_PTR(rc);
> +}
> --
> 2.43.0
>