Re: [PATCH v5] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

[Christoph Hellwig]

On Wed, Nov 18, 2020 at 08:12:43PM +0000, Ashish Kalra wrote:
> From: Ashish Kalra <ashish.kalra@xxxxxxx>
> 
> For SEV, all DMA to and from guest has to use shared
> (un-encrypted) pages. SEV uses SWIOTLB to make this
> happen without requiring changes to device drivers.
> However, depending on workload being run, the default
> 64MB of SWIOTLB might not be enough and SWIOTLB
> may run out of buffers to use for DMA, resulting
> in I/O errors and/or performance degradation for
> high I/O workloads.

FYI, you can use up 73 chars for your commit log.  This looks rather
compressed.