[PATCH] nvme-pci: fix prp list allocation

[Keith Busch]

On Sat, Feb 12, 2022 at 01:53:59PM -0700, Matt Waltz wrote:
> That is the wrong part of the specification, describing the PRP entries,
> not the list pointer. 

The text for qword alignment rules specifically says "PRP List entry",
as is associated with command's prp2 field.

> The relevant portion of the spec (2.0a figure
> 109 page 129) says:
> 
>     If this entry is not the first PRP entry in the command or a
>     PRP List pointer in a command, then the Offset portion of this
>     field shall be cleared to 0h

That only applies to chaining list elements. It does not apply to the
"PRP list pointer in a command". The driver allocates from the 256B dma
pool only for the command's PRP list pointer, so we're fine.