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Message-ID: <8e2cfde3-15fa-4e5a-02bf-0763abf10821@linux.alibaba.com>
Date: Tue, 18 Jul 2023 16:54:36 +0800
From: "guanghui.fgh" <guanghuifeng@...ux.alibaba.com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: guohanjun@...wei.com, sudeep.holla@....com, rafael@...nel.org,
linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, baolin.wang@...ux.alibaba.com,
alikernel-developer@...ux.alibaba.com, will@...nel.org,
catalin.marinas@....com, shameerali.kolothum.thodi@...wei.com
Subject: Re: [PATCH v3] ACPI/IORT: Remove erroneous id_count check in
iort_node_get_rmr_info()
在 2023/7/18 15:52, Lorenzo Pieralisi 写道:
> [+Catalin, Will, Shameer]
>
> 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@...ux.alibaba.com>
>> ---
>> drivers/acpi/arm64/iort.c | 3 ---
>> 1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index 3631230..56d8873 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -1007,9 +1007,6 @@ static void iort_node_get_rmr_info(struct acpi_iort_node *node,
>> for (i = 0; i < node->mapping_count; i++, map++) {
>> struct acpi_iort_node *parent;
>>
>> - if (!map->id_count)
>> - continue;
>> -
>> parent = ACPI_ADD_PTR(struct acpi_iort_node, iort_table,
>> map->output_reference);
>> if (parent != iommu)
>
> Shameer, I know this may look like overkill since the hunk we are
> removing is buggy but can you please test this patch on platforms
> with RMR to make sure we are not triggering regressions by removing
> it (by the specs that's what should be done but current firmware
> is always something to reckon with) ?
>
> Thanks,
> Lorenzo
Thanks for your response.
Firstly, I have tested iort rmr with one ID mapping and works well.
Secondly, When there is more than two id mappings, the buggly id_count
check has no effect(for the id_count is larger than zero).
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