From: Mian Yousaf Kaukab <ykaukab@suse.de>
To: Mikko Perttunen <mperttunen@nvidia.com>
Cc: arnd@arndb.de, gregkh@linuxfoundation.org,
linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] misc: sram: Only map reserved areas in Tegra SYSRAM
Date: Wed, 21 Jul 2021 16:08:17 +0200 [thread overview]
Message-ID: <20210721140817.GA140161@suse.de> (raw)
In-Reply-To: <20210715103423.1811101-1-mperttunen@nvidia.com>
On Thu, Jul 15, 2021 at 01:34:23PM +0300, Mikko Perttunen wrote:
> On Tegra186 and later, a portion of the SYSRAM may be reserved for use
> by TZ. Non-TZ memory accesses to this portion, including speculative
> accesses, trigger SErrors that bring down the system. This does also
> happen in practice occasionally (due to speculative accesses).
>
> To fix the issue, add a flag to the SRAM driver to only map the
> device tree-specified reserved areas depending on a flag set
> based on the compatibility string. This would not affect non-Tegra
> systems that rely on the entire thing being memory mapped.
>
> If 64K pages are being used, we cannot exactly map the 4K regions
> that are placed in SYSRAM - ioremap code instead aligns to closest
> 64K pages. However, since in practice the non-accessible memory area
> is 64K aligned, these mappings do not overlap with the non-accessible
> memory area and things work out.
>
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: Mian Yousaf Kaukab <ykaukab@suse.de>
prev parent reply other threads:[~2021-07-21 14:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 10:34 [PATCH v2] misc: sram: Only map reserved areas in Tegra SYSRAM Mikko Perttunen
2021-07-21 14:08 ` Mian Yousaf Kaukab [this message]
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