Re: [PATCH 3/5] nvme: add support for copy offload

Keith Busch
2025-05-22T04:30:02Z

On Wed, May 21, 2025 at 08:41:40PM -0700, Caleb Sander Mateos wrote:
> For the record, that change broke Linux hosts sending DSM commands to
> our NVMe controller, which was validating that the SGL length exactly
> matches the number of data bytes implied by the command. I'm sure
> we're in the minority of NVMe controller vendors in aggressively
> validating the NVMe command parameters, but it was unfortunate to
> discover this change in Linux's behavior.

This is a fabrics target you're talking about? I assume so because pci
would use PRP for a 4k payload, which doesn't encode transfer lengths.
All the offending controllers were pci, so maybe we could have
constrained the DSM over-allocation to that transport if we knew this
was causing problems for fabrics.