Re: [PATCH v2 1/2] optee: add page list to kernel private shared memory

From: Sumit Garg
Date: Fri Nov 10 2023 - 13:00:31 EST

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Hi Jens,

On Wed, 8 Nov 2023 at 15:57, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> Until now has kernel private shared memory allocated as dynamic shared
> memory (not from the static shared memory pool) been returned without a
> list of physical pages on allocations via RPC. To support allocations
> larger than one page add a list of physical pages for all allocations
> larger than one page.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> ---
> drivers/tee/optee/core.c | 40 +++++++++++++++++++++++++--------
> drivers/tee/optee/smc_abi.c | 45 +++++++++++++++++--------------------
> 2 files changed, 52 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> index 2a258bd3b6b5..a425eca0173d 100644
> --- a/drivers/tee/optee/core.c
> +++ b/drivers/tee/optee/core.c
> @@ -27,6 +27,7 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> unsigned long start))
> {
> unsigned int order = get_order(size);
> + unsigned int nr_pages = 1 << order;
> struct page *page;
> int rc = 0;
>
> @@ -39,12 +40,24 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> return -ENOMEM;
>
> shm->kaddr = page_address(page);
> - shm->paddr = page_to_phys(page);
> shm->size = PAGE_SIZE << order;
>
> - if (shm_register) {
> - unsigned int nr_pages = 1 << order, i;
> + /*
> + * If memory is registered immediately use a temporary page list
> + * and free it directly after the registration is completed.
> + *
> + * Else, if we have allocated more than one page store a page
> + * list in the struct tee_shm.
> + *
> + * Else, store the physical address of the single page that was
> + * allocated.
> + *
> + * optee_pool_op_free_helper() is responsible for freeing the
> + * resourses allocated in this function.
> + */

It looks a bit complex to me. Do we really need it to be conditional?
I was thinking if we can simplify this API as follows:

int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
size_t size, size_t align,
int (*shm_register)(struct tee_shm *shm))
{
unsigned int order = get_order(size);
unsigned int nr_pages = 1 << order, i;
struct page **pages;
struct page *page;
int rc = 0;

/*
* Ignore alignment since this is already going to be page aligned
* and there's no need for any larger alignment.
*/
page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
if (!page)
return -ENOMEM;

shm->kaddr = page_address(page);
shm->paddr = page_to_phys(page);
shm->size = PAGE_SIZE << order;

pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
if (!pages) {
rc = -ENOMEM;
goto err;
}

for (i = 0; i < nr_pages; i++)
pages[i] = page + i;

shm->pages = pages;
shm->num_pages = nr_pages;

if (shm_register) {
rc = shm_register(shm);
if (rc)
goto err;
}

return 0;

err:
kfree(pages);
free_pages((unsigned long)shm->kaddr, order);
return rc;
}

-Sumit

> + if (shm_register || nr_pages > 1) {
> struct page **pages;
> + unsigned int i;
>
> pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
> if (!pages) {
> @@ -55,17 +68,24 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> for (i = 0; i < nr_pages; i++)
> pages[i] = page + i;
>
> - rc = shm_register(shm->ctx, shm, pages, nr_pages,
> - (unsigned long)shm->kaddr);
> - kfree(pages);
> - if (rc)
> - goto err;
> + if (shm_register) {
> + rc = shm_register(shm->ctx, shm, pages, nr_pages,
> + (unsigned long)shm->kaddr);
> + kfree(pages);
> + if (rc)
> + goto err;
> + } else {
> + shm->pages = pages;
> + shm->num_pages = nr_pages;
> + }
> + } else {
> + shm->paddr = page_to_phys(page);
> }
>
> return 0;
> -
> err:
> free_pages((unsigned long)shm->kaddr, order);
> + shm->kaddr = NULL;
> return rc;
> }
>
> @@ -77,6 +97,8 @@ void optee_pool_op_free_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> shm_unregister(shm->ctx, shm);
> free_pages((unsigned long)shm->kaddr, get_order(shm->size));
> shm->kaddr = NULL;
> + kfree(shm->pages);
> + shm->pages = NULL;
> }
>
> static void optee_bus_scan(struct work_struct *work)
> diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c
> index d5b28fd35d66..b69410c7cc0a 100644
> --- a/drivers/tee/optee/smc_abi.c
> +++ b/drivers/tee/optee/smc_abi.c
> @@ -678,10 +678,11 @@ static void handle_rpc_func_cmd_shm_alloc(struct tee_context *ctx,
> struct optee_msg_arg *arg,
> struct optee_call_ctx *call_ctx)
> {
> - phys_addr_t pa;
> struct tee_shm *shm;
> size_t sz;
> size_t n;
> + struct page **pages;
> + size_t page_count;
>
> arg->ret_origin = TEEC_ORIGIN_COMMS;
>
> @@ -716,32 +717,23 @@ static void handle_rpc_func_cmd_shm_alloc(struct tee_context *ctx,
> return;
> }
>
> - if (tee_shm_get_pa(shm, 0, &pa)) {
> - arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> - goto bad;
> - }
> -
> - sz = tee_shm_get_size(shm);
> -
> - if (tee_shm_is_dynamic(shm)) {
> - struct page **pages;
> + /*
> + * If there are pages it's dynamically allocated shared memory (not
> + * from the reserved shared memory pool) and needs to be
> + * registered.
> + */
> + pages = tee_shm_get_pages(shm, &page_count);
> + if (pages) {
> u64 *pages_list;
> - size_t page_num;
> -
> - pages = tee_shm_get_pages(shm, &page_num);
> - if (!pages || !page_num) {
> - arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
> - goto bad;
> - }
>
> - pages_list = optee_allocate_pages_list(page_num);
> + pages_list = optee_allocate_pages_list(page_count);
> if (!pages_list) {
> arg->ret = TEEC_ERROR_OUT_OF_MEMORY;
> goto bad;
> }
>
> call_ctx->pages_list = pages_list;
> - call_ctx->num_entries = page_num;
> + call_ctx->num_entries = page_count;
>
> arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_TMEM_OUTPUT |
> OPTEE_MSG_ATTR_NONCONTIG;
> @@ -752,17 +744,22 @@ static void handle_rpc_func_cmd_shm_alloc(struct tee_context *ctx,
> arg->params[0].u.tmem.buf_ptr = virt_to_phys(pages_list) |
> (tee_shm_get_page_offset(shm) &
> (OPTEE_MSG_NONCONTIG_PAGE_SIZE - 1));
> - arg->params[0].u.tmem.size = tee_shm_get_size(shm);
> - arg->params[0].u.tmem.shm_ref = (unsigned long)shm;
>
> - optee_fill_pages_list(pages_list, pages, page_num,
> + optee_fill_pages_list(pages_list, pages, page_count,
> tee_shm_get_page_offset(shm));
> } else {
> + phys_addr_t pa;
> +
> + if (tee_shm_get_pa(shm, 0, &pa)) {
> + arg->ret = TEEC_ERROR_BAD_PARAMETERS;
> + goto bad;
> + }
> +
> arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_TMEM_OUTPUT;
> arg->params[0].u.tmem.buf_ptr = pa;
> - arg->params[0].u.tmem.size = sz;
> - arg->params[0].u.tmem.shm_ref = (unsigned long)shm;
> }
> + arg->params[0].u.tmem.size = tee_shm_get_size(shm);
> + arg->params[0].u.tmem.shm_ref = (unsigned long)shm;
>
> arg->ret = TEEC_SUCCESS;
> return;
> --
> 2.34.1
>

Next message: syzbot: "Re: [syzbot] [net?] BUG: unable to handle kernel paging request in nsim_bpf"
Previous message: Julia Zhang: "[PATCH 0/2] Add RESOURCE_GET_LAYOUT ioctl"
In reply to: Jens Wiklander: "[PATCH v2 1/2] optee: add page list to kernel private shared memory"
Next in thread: Jens Wiklander: "Re: [PATCH v2 1/2] optee: add page list to kernel private shared memory"
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