All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Jan Beulich" <JBeulich@suse.com>
To: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Brian Woods <brian.woods@amd.com>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [PATCH 1/2] x86/SVM-IOMMU: Don't opencode memcpy() in queue_iommu_command()
Date: Mon, 24 Sep 2018 06:32:20 -0600	[thread overview]
Message-ID: <5BA8D95402000078001EB255@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <5fb496fa9dd947039631a3520fda7d6c@AMSPEX02CL03.citrite.net>

>>> On 24.09.18 at 14:18, <Paul.Durrant@citrix.com> wrote:
>> From: Jan Beulich [mailto:JBeulich@suse.com]
>> Sent: 24 September 2018 13:16
>> 
>> All writes to the ring occur strictly before the update of the tail
>> pointer
> 
> ...unless the compiler decides to re-order. There's no barrier.

But there is (an implied) one, inside writel() (due to the "volatile").
Everything ahead of the writel() invocation may be stored in any
order.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  parent reply	other threads:[~2018-09-24 12:32 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-24 10:55 [PATCH 1/2] x86/SVM-IOMMU: Don't opencode memcpy() in queue_iommu_command() Andrew Cooper
2018-09-24 10:55 ` [PATCH 2/2] x86/SVM-IOMMU: Drop get_field_from_byte() Andrew Cooper
2018-09-24 12:07   ` Paul Durrant
2018-09-24 12:17   ` Jan Beulich
2018-10-04 23:00   ` Woods, Brian
2018-10-05  8:22   ` Roger Pau Monné
2018-09-24 11:59 ` [PATCH 1/2] x86/SVM-IOMMU: Don't opencode memcpy() in queue_iommu_command() Paul Durrant
2018-09-24 12:05   ` Andrew Cooper
2018-09-24 12:09     ` Paul Durrant
2018-09-24 12:16       ` Jan Beulich
2018-09-24 12:18         ` Paul Durrant
2018-09-24 12:24           ` Andrew Cooper
2018-09-24 12:28             ` Paul Durrant
2018-09-24 12:32           ` Jan Beulich [this message]
2018-09-24 12:19       ` Andrew Cooper
2018-09-24 12:09   ` Jan Beulich
2018-09-24 12:14 ` Jan Beulich
2018-10-04 23:03 ` Woods, Brian
2018-10-05  8:22 ` Roger Pau Monné

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=5BA8D95402000078001EB255@prv1-mh.provo.novell.com \
    --to=jbeulich@suse.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=brian.woods@amd.com \
    --cc=paul.durrant@citrix.com \
    --cc=roger.pau@citrix.com \
    --cc=suravee.suthikulpanit@amd.com \
    --cc=wei.liu2@citrix.com \
    --cc=xen-devel@lists.xen.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.