On 2023/7/18 16:56, Shameerali Kolothum Thodi wrote:

quoted

[+Catalin, Will, Shameer]

On Mon, Jul 17, 2023 at 07:33:45PM +0800, Guanghui Feng wrote:

quoted

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")

quoted

Signed-off-by: Guanghui Feng<redacted>
---
  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,

quoted

  	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) ?

Yes, that is a valid fix. Unlikely it will be a problem. Anyway, I have requested
Hanjun to help with the testing as I don't have a test setup with me now.

Valid fix for me as well, we had a firmware bug which reported the
numbers of ID as 1 when we only have one ID mapping, so remove the
check is fine for the old firmware, but to make it sure, we need some
test before give it a pass.

Hanjun, please help.

I need some time to get it properly tested on two versions of firmware,
and get the test machine properly setup, please allow me give the
feedback next week.

Thanks
Hanjun

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