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Date:   Thu, 27 Jul 2023 16:00:43 +0100
From:   Will Deacon <will@kernel.org>
To:     Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Guanghui Feng <guanghuifeng@linux.alibaba.com>,
        guohanjun@huawei.com, sudeep.holla@arm.com, rafael@kernel.org,
        linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, baolin.wang@linux.alibaba.com,
        alikernel-developer@linux.alibaba.com
Subject: Re: [PATCH v3] ACPI/IORT: Remove erroneous id_count check in
 iort_node_get_rmr_info()
Message-ID: <20230727150042.GC19940@willie-the-truck>
References: <1689593625-45213-1-git-send-email-guanghuifeng@linux.alibaba.com>
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 <ZMJ4JnlVlqkO3E0P@arm.com>
 <ZMJ8jeLs69env0pL@lpieralisi>
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On Thu, Jul 27, 2023 at 04:17:49PM +0200, Lorenzo Pieralisi wrote:
> On Thu, Jul 27, 2023 at 02:59:02PM +0100, Catalin Marinas wrote:
> > On Thu, Jul 27, 2023 at 03:39:27PM +0200, Lorenzo Pieralisi wrote:
> > > On Mon, Jul 17, 2023 at 07:33:45PM +0800, Guanghui Feng wrote:
> > > > According to the ARM IORT specifications DEN 0049 issue E,
> > > > the "Number of IDs" field in the ID mapping format reports
> > > > the number of IDs in the mapping range minus one.
> > > > 
> > > > In iort_node_get_rmr_info(), we erroneously skip ID mappings
> > > > whose "Number of IDs" equal to 0, resulting in valid mapping
> > > > nodes with a single ID to map being skipped, which is wrong.
> > > > 
> > > > Fix iort_node_get_rmr_info() by removing the bogus id_count
> > > > check.
> > > > 
> > > > Fixes: 491cf4a6735a ("ACPI/IORT: Add support to retrieve IORT RMR reserved regions")
> > > > Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
> > > > ---
> > > >  drivers/acpi/arm64/iort.c | 3 ---
> > > >  1 file changed, 3 deletions(-)
> > > 
> > > Acked-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
> > > 
> > > Catalin/Will,
> > > 
> > > can you pick this up please ?
> > 
> > Would you like it merged in 6.5 or 6.6 is fine?
> 
> It is definitely a fix - I don't think that's super urgent
> though, bug has been there since v6.0 so the fix can probably
> wait to trickle back from v6.6.

On the flip side, it's a fix, Hanjun has tested it and we have a few
weeks in case we need to revert it.

So I'd be inclined to say Catalin should pick it up for 6.5, unless
there's a good reason to wait?

Will