linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Marc Zyngier <maz@kernel.org>
To: Jianyong Wu <jianyong.wu@arm.com>
Cc: james.morse@arm.com, andre.przywara@arm.com,
	lushenming@huawei.com, kvm@vger.kernel.org,
	kvmarm@lists.cs.columbia.edu, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, justin.he@arm.com
Subject: Re: [PATCH] doc/arm: take care restore order of GICR_* in ITS restore
Date: Wed, 21 Jul 2021 10:53:37 +0100	[thread overview]
Message-ID: <87czrc2dsu.wl-maz@kernel.org> (raw)
In-Reply-To: <20210721092019.144088-1-jianyong.wu@arm.com>

On Wed, 21 Jul 2021 10:20:19 +0100,
Jianyong Wu <jianyong.wu@arm.com> wrote:
> 
> When restore GIC/ITS, GICR_CTLR must be restored after GICR_PROPBASER
> and GICR_PENDBASER. That is important, as both of GICR_PROPBASER and
> GICR_PENDBASER will fail to be loaded when lpi has enabled yet in
> GICR_CTLR. Keep the restore order above will avoid that issue.
> Shout it out at the doc is very helpful that may avoid lots of debug work.

But that's something that is already mandated by the architecture,
isn't it? See "5.1 LPIs" in the architecture spec:

<quote>

If GICR_PROPBASER is updated when GICR_CTLR.EnableLPIs == 1, the
effects are UNPREDICTABLE.

[...]

If GICR_PENDBASER is updated when GICR_CTLR.EnableLPIs == 1, the
effects are UNPREDICTABLE.

</quote>

The point of this documentation is to make it explicit what is *not*
covered by the architecture. Anything that is in the architecture
still applies, and shouldn't be overlooked.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

  reply	other threads:[~2021-07-21 10:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21  9:20 Jianyong Wu
2021-07-21  9:53 ` Marc Zyngier [this message]
2021-07-22  2:49   ` Jianyong Wu
2021-07-22  8:11     ` Marc Zyngier
2021-07-23  5:27       ` Jianyong Wu

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=87czrc2dsu.wl-maz@kernel.org \
    --to=maz@kernel.org \
    --cc=andre.przywara@arm.com \
    --cc=james.morse@arm.com \
    --cc=jianyong.wu@arm.com \
    --cc=justin.he@arm.com \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lushenming@huawei.com \
    --subject='Re: [PATCH] doc/arm: take care restore order of GICR_* in ITS restore' \
    /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

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).