Re: [PATCH 14/15] swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 3/14/22 3:31 AM, Christoph Hellwig wrote:
> @@ -314,6 +293,7 @@ void __init swiotlb_init(bool addressing_limit, unsigned int flags)
>   int swiotlb_init_late(size_t size, gfp_t gfp_mask,
>   		int (*remap)(void *tlb, unsigned long nslabs))
>   {
> +	struct io_tlb_mem *mem = &io_tlb_default_mem;
>   	unsigned long nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
>   	unsigned long bytes;
>   	unsigned char *vstart = NULL;
> @@ -355,33 +335,28 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
>   			(PAGE_SIZE << order) >> 20);
>   		nslabs = SLABS_PER_PAGE << order;
>   	}
> -	rc = swiotlb_late_init_with_tbl(vstart, nslabs);
> -	if (rc)
> -		free_pages((unsigned long)vstart, order);
> -
> -	return rc;
> -}
> -
> -int
> -swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> -{
> -	struct io_tlb_mem *mem = &io_tlb_default_mem;
> -	unsigned long bytes = nslabs << IO_TLB_SHIFT;
>   
> -	if (swiotlb_force_disable)
> -		return 0;
> +	if (remap)
> +		rc = remap(vstart, nslabs);
> +	if (rc) {
> +		free_pages((unsigned long)vstart, order);
>   
> -	/* protect against double initialization */
> -	if (WARN_ON_ONCE(mem->nslabs))
> -		return -ENOMEM;
> +		/* Min is 2MB */
> +		if (nslabs <= 1024)
> +			return rc;
> +		nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
> +		goto retry;
> +	}


We now end up with two attempts to remap. I think this second one is what we want since it solves the problem I pointed in previous patch.


-boris