Re: [PATCH v2 1/2] tee: amdtee: use page_alloc_exact() for memory allocations

[Rijo Thomas <Rijo-john.Thomas@amd.com>]

On 8/30/2023 1:49 AM, Devaraj Rangasamy wrote:
> Use page_alloc_exact() to get buffers, instead of
> get_free_pages(), so as to avoid wastage of memory.
> Currently get_free_pages() is allocating at next order,
> while page_alloc_exact() will free the unused pages.
> 
> Signed-off-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
> ---
>  v2:
>  * Replaced __get_free_pages() with alloc_pages_exact().
> 

Reviewed-by: Rijo Thomas <Rijo-john.Thomas@amd.com>

Thanks,
Rijo

>  drivers/tee/amdtee/shm_pool.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/tee/amdtee/shm_pool.c b/drivers/tee/amdtee/shm_pool.c
> index f0303126f199..156e8a6f631f 100644
> --- a/drivers/tee/amdtee/shm_pool.c
> +++ b/drivers/tee/amdtee/shm_pool.c
> @@ -4,6 +4,7 @@
>   */
>  
>  #include <linux/slab.h>
> +#include <linux/mm.h>
>  #include <linux/tee_drv.h>
>  #include <linux/psp.h>
>  #include "amdtee_private.h"
> @@ -11,26 +12,23 @@
>  static int pool_op_alloc(struct tee_shm_pool *pool, struct tee_shm *shm,
>  			 size_t size, size_t align)
>  {
> -	unsigned int order = get_order(size);
> -	unsigned long va;
> +	void *va;
>  	int rc;
>  
> -	/*
> -	 * Ignore alignment since this is already going to be page aligned
> -	 * and there's no need for any larger alignment.
> -	 */
> -	va = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
> +	size = PAGE_ALIGN(size);
> +
> +	va = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
>  	if (!va)
>  		return -ENOMEM;
>  
>  	shm->kaddr = (void *)va;
>  	shm->paddr = __psp_pa((void *)va);
> -	shm->size = PAGE_SIZE << order;
> +	shm->size = size;
>  
>  	/* Map the allocated memory in to TEE */
>  	rc = amdtee_map_shmem(shm);
>  	if (rc) {
> -		free_pages(va, order);
> +		free_pages_exact(va, size);
>  		shm->kaddr = NULL;
>  		return rc;
>  	}
> @@ -42,7 +40,7 @@ static void pool_op_free(struct tee_shm_pool *pool, struct tee_shm *shm)
>  {
>  	/* Unmap the shared memory from TEE */
>  	amdtee_unmap_shmem(shm);
> -	free_pages((unsigned long)shm->kaddr, get_order(shm->size));
> +	free_pages_exact(shm->kaddr, shm->size);
>  	shm->kaddr = NULL;
>  }
>