nvme: Discard workaround for non-conformant devices

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Users observe IOMMU related errors when performing discard on nvme from
non-compliant nvme devices reading beyond the end of the DMA mapped
ranges to discard.

Two different variants of this behavior have been observed: SM22XX
controllers round up the read size to a multiple of 512 bytes, and Phison
E12 unconditionally reads the maximum discard size allowed by the spec
(256 segments or 4kB).

Make nvme_setup_discard unconditionally allocate the maximum DSM buffer
so the driver DMA maps a memory range that will always succeed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=202665 many
Signed-off-by: Eduard Hasenleithner <eduard@hasenleithner.at>
[changelog, use existing define, kernel coding style]
Signed-off-by: Keith Busch <kbusch@kernel.org>

...

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Eduard Hasenleithner 2019-11-12 21:55:01 +01:00 • committed by Keith Busch

parent 400b6a7b13

commit 530436c45e

1 changed files with 9 additions and 3 deletions

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drivers/nvme/host/core.c

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