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From: Tom Lendacky <thomas.lendacky@amd.com>
To: Christoph Hellwig <hch@lst.de>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	xen-devel@lists.xenproject.org, iommu@lists.linux-foundation.org
Subject: Re: [PATCH 7/7] swiotlb: don't override the command line in swiotlb_adjust_size
Date: Fri, 23 Apr 2021 00:23:23 -0500	[thread overview]
Message-ID: <5df0f10e-4c70-6554-6cb8-10ea3acde92b@amd.com> (raw)
In-Reply-To: <20210422071921.1428607-8-hch@lst.de>

On 4/22/21 2:19 AM, Christoph Hellwig wrote:
> When the user specified an explicit swiotlb size on the command line,
> the achitecture code should not override it.
> 
> Fixes: 2cbc2776efe4 ("swiotlb: remove swiotlb_nr_tbl")
> Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I tested this patchset and I'm not able to get the override via the
command line or via the SEV adjustment function. Looking at the code,
swiotlb_default_size is initialized, so the call to swiotlb_adjust_size()
always returns without setting the new size.

Thanks,
Tom

> ---
>  kernel/dma/swiotlb.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 87d06ddf4753f3..aef02a3825b494 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -106,7 +106,9 @@ void swiotlb_set_max_segment(unsigned int val)
>  
>  unsigned long swiotlb_size_or_default(void)
>  {
> -	return swiotlb_default_size;
> +	if (swiotlb_default_size)
> +		return swiotlb_default_size;
> +	return IO_TLB_DEFAULT_SIZE;
>  }
>  
>  void __init swiotlb_adjust_size(unsigned long size)
> @@ -116,6 +118,8 @@ void __init swiotlb_adjust_size(unsigned long size)
>  	 * architectures such as those supporting memory encryption to
>  	 * adjust/expand SWIOTLB size for their use.
>  	 */
> +	if (swiotlb_default_size)
> +		return;
>  	swiotlb_default_size = ALIGN(size, IO_TLB_SEGSIZE << IO_TLB_SHIFT);
>  	pr_info("SWIOTLB bounce buffer size adjusted to %luMB",
>  		swiotlb_default_size >> 20);
> 


      reply	other threads:[~2021-04-23  5:24 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  7:19 cleanup and fix swiotlb sizing Christoph Hellwig
2021-04-22  7:19 ` [PATCH 1/7] swiotlb: pass bytes instead of nslabs to swiotlb_init_with_tbl Christoph Hellwig
2021-04-22  7:19 ` [PATCH 2/7] swiotlb: use swiotlb_size_or_default in swiotlb_init Christoph Hellwig
2021-04-22  7:19 ` [PATCH 3/7] swiotlb: use swiotlb_adjust_size in setup_io_tlb_npages Christoph Hellwig
2021-04-22  7:19 ` [PATCH 4/7] powerpc/pseries: simplify svm_swiotlb_init Christoph Hellwig
2021-04-22  7:19 ` [PATCH 5/7] MIPS/octeon: simplify swiotlb initialization Christoph Hellwig
2021-04-22  7:19 ` [PATCH 6/7] swiotlb: replace default_nslabs with a byte value Christoph Hellwig
2021-04-22  7:19 ` [PATCH 7/7] swiotlb: don't override the command line in swiotlb_adjust_size Christoph Hellwig
2021-04-23  5:23   ` Tom Lendacky [this message]

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