Linux-ARM-MSM Archive on lore.kernel.org
 help / color / Atom feed
From: Marc Gonzalez <marc.w.gonzalez@free.fr>
To: Joerg Roedel <joro@8bytes.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	MSM <linux-arm-msm@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	iommu <iommu@lists.linux-foundation.org>,
	AngeloGioacchino Del Regno <kholk11@gmail.com>,
	Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
	Andy Gross <agross@kernel.org>
Subject: Re: [PATCH v3] iommu/arm-smmu: Avoid constant zero in TLBI writes
Date: Fri, 7 Jun 2019 12:40:05 +0200
Message-ID: <f7b2e799-e3b1-ad40-c7b7-153f00323636@free.fr> (raw)
In-Reply-To: <20190605121900.GJ15030@fuggles.cambridge.arm.com>

On 05/06/2019 14:19, Will Deacon wrote:

> On Mon, Jun 03, 2019 at 02:15:37PM +0200, Marc Gonzalez wrote:
>
>> From: Robin Murphy <robin.murphy@arm.com>
>>
>> Apparently, some Qualcomm arm64 platforms which appear to expose their
>> SMMU global register space are still, in fact, using a hypervisor to
>> mediate it by trapping and emulating register accesses. Sadly, some
>> deployed versions of said trapping code have bugs wherein they go
>> horribly wrong for stores using r31 (i.e. XZR/WZR) as the source
>> register.
>>
>> While this can be mitigated for GCC today by tweaking the constraints
>> for the implementation of writel_relaxed(), to avoid any potential
>> arms race with future compilers more aggressively optimising register
>> allocation, the simple way is to just remove all the problematic
>> constant zeros. For the write-only TLB operations, the actual value is
>> irrelevant anyway and any old nearby variable will provide a suitable
>> GPR to encode. The one point at which we really do need a zero to clear
>> a context bank happens before any of the TLB maintenance where crashes
>> have been reported, so is apparently not a problem... :/
>>
>> Reported-by: AngeloGioacchino Del Regno <kholk11@gmail.com>
>> Tested-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
> 
> Acked-by: Will Deacon <will.deacon@arm.com>
> 
> Joerg -- Please can you take this as a fix for 5.2, with a Cc stable?

Hello Joerg,

Can you ping this thread once this patch hits linux-next, so I can
ask Bjorn to pick up the 8998 ANOC1 DT node, and the PCIe DT node
that requires ANOC1.

Bjorn: for ANOC1, a small fixup: s/arm,smmu/iommu/

https://patchwork.kernel.org/project/linux-arm-msm/list/?series=99701
https://patchwork.kernel.org/patch/10895341/

Regards.

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-29 11:55 [PATCH v2] " Marc Gonzalez
2019-05-29 13:05 ` Will Deacon
2019-05-29 14:31   ` Marc Gonzalez
2019-06-03 12:15     ` [PATCH v3] " Marc Gonzalez
2019-06-05 12:19       ` Will Deacon
2019-06-07 10:40         ` Marc Gonzalez [this message]
2019-06-12  8:10       ` Joerg Roedel
2019-06-14 11:24         ` Marc Gonzalez

Reply instructions:

You may reply publically 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=f7b2e799-e3b1-ad40-c7b7-153f00323636@free.fr \
    --to=marc.w.gonzalez@free.fr \
    --cc=agross@kernel.org \
    --cc=bjorn.andersson@linaro.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jeffrey.l.hugo@gmail.com \
    --cc=joro@8bytes.org \
    --cc=kholk11@gmail.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=will.deacon@arm.com \
    /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

Linux-ARM-MSM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-msm/0 linux-arm-msm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-msm linux-arm-msm/ https://lore.kernel.org/linux-arm-msm \
		linux-arm-msm@vger.kernel.org
	public-inbox-index linux-arm-msm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-arm-msm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git