linux-kernel - Re: [PATCH v2 1/2] tee: amdtee: use page_alloc

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Message-ID: <0ad21a06-7a64-7d71-16f6-0bded64b6921@amd.com>
Date:   Wed, 4 Oct 2023 16:29:41 +0530
From:   Rijo Thomas <Rijo-john.Thomas@....com>
To:     Devaraj Rangasamy <Devaraj.Rangasamy@....com>,
        Jonathan Corbet <corbet@....net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        SivaSangeetha SK <SivaSangeetha.SK@....com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Ross Lagerwall <ross.lagerwall@...rix.com>,
        Yuntao Wang <ytcoode@...il.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Tom Lendacky <thomas.lendacky@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        op-tee@...ts.trustedfirmware.org
Cc:     Mythri PK <Mythri.Pandeshwarakrishna@....com>,
        Nimesh Easow <Nimesh.Easow@....com>
Subject: Re: [PATCH v2 1/2] tee: amdtee: use page_alloc_exact() for memory
 allocations



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@....com>
> ---
>  v2:
>  * Replaced __get_free_pages() with alloc_pages_exact().
> 

Reviewed-by: Rijo Thomas <Rijo-john.Thomas@....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;
>  }
>