nvme-pci: use sgls for all user requests if possible

[ Upstream commit 6fad84a4 ]

If the device supports SGLs, use these for all user requests. This
format encodes the expected transfer length so it can catch short buffer
errors in a user command, whether it occurred accidently or maliciously.

For controllers that support SGL data mode, this is a viable mitigation
to CVE-2023-6238. For controllers that don't support SGLs, log a warning
in the passthrough path since not having the capability can corrupt
data if the interface is not used correctly.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Stable-dep-of: 00817f0f ("nvme-ioctl: fix leaked requests on mapping error")
Signed-off-by: Sasha Levin <sashal@kernel.org>