linux-kernel - [PATCH] of/fdt: Don't worry about non-memory region overlap for no-map

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Message-Id: <20210520012731.3731314-1-swboyd@chromium.org>
Date:   Wed, 19 May 2021 18:27:31 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Rob Herring <robh@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Quentin Perret <qperret@...gle.com>
Subject: [PATCH] of/fdt: Don't worry about non-memory region overlap for no-map

In commit 8a5a75e5e9e5 ("of/fdt: Make sure no-map does not remove
already reserved regions") we returned -EBUSY when trying to mark
regions as no-map when they're in the reserved memory node. This if
condition will still trigger though if the DT has a /memreserve/ that
completely subsumes the no-map memory carveouts in the reserved memory
node. Let's only consider this to be a problem if we're trying to mark a
region as no-map and it is actually memory. If it isn't memory,
presumably it was removed from the memory map via /memreserve/ and thus
can't be mapped anyway.

This silences a warning seen at boot for me on sc7180-trogdor.dtsi
boards that have /memreserve/ coming from the bootloader and those
reserved regions overlap with the carveouts that we want to use in DT
for other purposes like communicating with remote processors.

Cc: Douglas Anderson <dianders@...omium.org>
Cc: Nicolas Boichat <drinkcat@...omium.org>
Cc: Quentin Perret <qperret@...gle.com>
Fixes: 8a5a75e5e9e5 ("of/fdt: Make sure no-map does not remove already reserved regions")
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/of/fdt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index ba17a80b8c79..be13b4b6c2d8 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1161,7 +1161,8 @@ int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
 		 * If the memory is already reserved (by another region), we
 		 * should not allow it to be marked nomap.
 		 */
-		if (memblock_is_region_reserved(base, size))
+		if (memblock_is_region_memory(base, size) &&
+		    memblock_is_region_reserved(base, size))
 			return -EBUSY;

 		return memblock_mark_nomap(base, size);

base-commit: 6efb943b8616ec53a5e444193dccf1af9ad627b5
-- 
https://chromeos.dev