linux-nvme.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Philip Langdale <philipl@overt.org>
To: linux-nvme@lists.infradead.org
Subject: IOMMU incompatibility with discard on certain devices
Date: Sun, 10 Nov 2019 07:11:02 -0800	[thread overview]
Message-ID: <20191110071102.2b94fca7@fido6> (raw)

Hi all,

I'm writing to highlight a problem that is affecting users of certain
nvme ssds as discussed here:

https://bugzilla.kernel.org/show_bug.cgi?id=202665

The problem has been narrowed down to some devices always doing page
aligned reads when reading the list of segments to discard, rather than
reading the exact size passed. When an enforcing IOMMU is used (both
Intel and AMD systems exhibit the same behaviour in the reports), these
page-aligned reads are rejected because they are larger than the actual
allocations.

In the bugzilla bug, a patch was proposed to add a device quirk that
ensures the segment list allocation is page-aligned, and this solved
the problem for everyone who tried it. Another patch was offered that
simply always page-aligns the allocations and perhaps that's
actually better?

If I was the patch author, I would have sent the quirk patch to the
list, but as I am not, I can't sign-off on it. It would be great if
someone could look at this, and we can get a fix committed.

Thanks,

--phil

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

                 reply	other threads:[~2019-11-10 15:19 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191110071102.2b94fca7@fido6 \
    --to=philipl@overt.org \
    --cc=linux-nvme@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).