From 3ad96787949a96256931ca59aff73ea604bc0e6c Mon Sep 17 00:00:00 2001 From: Bjorn Andersson Date: Wed, 20 Sep 2023 19:37:30 -0700 Subject: [PATCH] dt-bindings: reserved-memory: rmtfs: Allow guard pages On some Qualcomm platforms the firwmare, or hardware, does not gracefully handle memory protection of the rmtfs memory region when placed adjacent to other protected region. Some DeviceTree authors have worked around this issue by explicitly reserving the space around the region, but this prevents such author to use rely on the OS to place the region, through the use of "size" (instead of a fixed location). Introduce a flag to indicate that guard pages need be carved at the beginning and end of the memory region. The user shall account for the two pages in the defined size. Signed-off-by: Bjorn Andersson Reviewed-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20230920-rmtfs-mem-guard-pages-v3-1-305b37219b78@quicinc.com Signed-off-by: Bjorn Andersson --- .../bindings/reserved-memory/qcom,rmtfs-mem.yaml | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml index bab982f00485..46407e9c1d4f 100644 --- a/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml +++ b/Documentation/devicetree/bindings/reserved-memory/qcom,rmtfs-mem.yaml @@ -26,6 +26,17 @@ properties: description: > identifier of the client to use this region for buffers + qcom,use-guard-pages: + type: boolean + description: > + Indicates that the firmware, or hardware, does not gracefully handle + memory protection of this region when placed adjacent to other protected + memory regions, and that padding around the used portion of the memory + region is necessary. + + When this is set, the first and last page should be left unused, and the + effective size of the region will thereby shrink with two pages. + qcom,vmid: $ref: /schemas/types.yaml#/definitions/uint32-array description: >