linux-kernel - Re: [PATCH 1/2] habanalabs: make sure device mem alloc is page aligned

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Date:   Sat, 26 Mar 2022 06:16:29 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Oded Gabbay <ogabbay@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Ohad Sharabi <osharabi@...ana.ai>
Subject: Re: [PATCH 1/2] habanalabs: make sure device mem alloc is page
 aligned

On Mon, Feb 21, 2022 at 10:49:13AM +0200, Oded Gabbay wrote:
> From: Ohad Sharabi <osharabi@...ana.ai>
> 
> Working with MMU that supports multiple page sizes requires that mapping
> of a page of a certain size will be aligned to the same size (e.g. the
> physical address of 32MB page shall be aligned to 32MB).
> 
> To achieve this the gen_poll allocation is now using the "align" variant
> to comply with the alignment requirements.
> 
> Signed-off-by: Ohad Sharabi <osharabi@...ana.ai>
> Reviewed-by: Oded Gabbay <ogabbay@...nel.org>
> Signed-off-by: Oded Gabbay <ogabbay@...nel.org>
> ---
>  drivers/misc/habanalabs/common/memory.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
> index 385bf3448c73..0b76f40e9930 100644
> --- a/drivers/misc/habanalabs/common/memory.c
> +++ b/drivers/misc/habanalabs/common/memory.c
> @@ -90,8 +90,8 @@ static int alloc_device_memory(struct hl_ctx *ctx, struct hl_mem_in *args,
>  	struct hl_vm_phys_pg_pack *phys_pg_pack;
>  	u64 paddr = 0, total_size, num_pgs, i;
>  	u32 num_curr_pgs, page_size;
> -	int handle, rc;
>  	bool contiguous;
> +	int handle, rc;
>  
>  	num_curr_pgs = 0;
>  
> @@ -110,7 +110,11 @@ static int alloc_device_memory(struct hl_ctx *ctx, struct hl_mem_in *args,
>  	contiguous = args->flags & HL_MEM_CONTIGUOUS;
>  
>  	if (contiguous) {
> -		paddr = (u64) gen_pool_alloc(vm->dram_pg_pool, total_size);
> +		if (is_power_of_2(page_size))
> +			paddr = (u64) gen_pool_dma_alloc_align(vm->dram_pg_pool, total_size, NULL,
> +							page_size);

I see that this is fixed in -next, but ...

> +		else
> +			paddr = (u64) gen_pool_alloc(vm->dram_pg_pool, total_size);

... this has an unnecessary typecast in -next (gen_pool_alloc() returns
unsigned long, not a pointer), and ...

>  		if (!paddr) {
>  			dev_err(hdev->dev,
>  				"failed to allocate %llu contiguous pages with total size of %llu\n",
> @@ -144,9 +148,14 @@ static int alloc_device_memory(struct hl_ctx *ctx, struct hl_mem_in *args,
>  			phys_pg_pack->pages[i] = paddr + i * page_size;
>  	} else {
>  		for (i = 0 ; i < num_pgs ; i++) {
> -			phys_pg_pack->pages[i] = (u64) gen_pool_alloc(
> -							vm->dram_pg_pool,
> -							page_size);
> +			if (is_power_of_2(page_size))
> +				phys_pg_pack->pages[i] =
> +						(u64) gen_pool_dma_alloc_align(vm->dram_pg_pool,
> +										page_size, NULL,
> +										page_size);

... this still causes a compile error when building 32-bit test images.

Building mips:allmodconfig ... failed
--------------
Error log:
drivers/misc/habanalabs/common/memory.c: In function 'alloc_device_memory':
drivers/misc/habanalabs/common/memory.c:153:49: error: cast from pointer to integer of different size

Guenter

> +			else
> +				phys_pg_pack->pages[i] = (u64) gen_pool_alloc(vm->dram_pg_pool,
> +										page_size);
>  			if (!phys_pg_pack->pages[i]) {
>  				dev_err(hdev->dev,
>  					"Failed to allocate device memory (out of memory)\n");
> -- 
> 2.25.1
>