linux-kernel - [PATCH 1/2] of: fdt: allow to register arch specific hook validating reserved region

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Message-ID: <20250417221938.579452-2-jaszczyk@chromium.org>
Date: Thu, 17 Apr 2025 22:19:37 +0000
From: Grzegorz Jaszczyk <jaszczyk@...omium.org>
To: tglx@...utronix.de,
	robh@...nel.org
Cc: mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	saravanak@...gle.com,
	dmaluka@...omium.org,
	bgrzesik@...gle.com,
	jaszczyk@...gle.com,
	ilpo.jarvinen@...ux.intel.com,
	usamaarif642@...il.com,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	tnowicki@...gle.com,
	mazurekm@...gle.com,
	vineethrp@...gle.com
Subject: [PATCH 1/2] of: fdt: allow to register arch specific hook validating reserved region

From: Grzegorz Jaszczyk <jaszczyk@...gle.com>

Add a possibility to register arch specific hook which will validate if
reserved-memory region passed by DT is valid (e.g. in case of x86, which
allows to boot with both ACPI and DT at the same time, registered hook
will validate if reserved-memory region passed by DT is covered by E820
reserved region entry).

Signed-off-by: Grzegorz Jaszczyk <jaszczyk@...gle.com>
---
 drivers/of/of_reserved_mem.c | 14 ++++++++++++++
 include/linux/of_fdt.h       |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index ee2e31522d7e..bb66a019e3e2 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -27,6 +27,7 @@
 
 #include "of_private.h"
 
+static bool __initdata (*arch_is_region_reserved)(phys_addr_t base, phys_addr_t size);
 static struct reserved_mem reserved_mem_array[MAX_RESERVED_REGIONS] __initdata;
 static struct reserved_mem *reserved_mem __refdata = reserved_mem_array;
 static int total_reserved_mem_cnt = MAX_RESERVED_REGIONS;
@@ -131,6 +132,13 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
 static int __init early_init_dt_reserve_memory(phys_addr_t base,
 					       phys_addr_t size, bool nomap)
 {
+	if (arch_is_region_reserved && !arch_is_region_reserved(base, size)) {
+		phys_addr_t end = base + size - 1;
+
+		pr_err("mem %pa-%pa not arch reserved\n", &base, &end);
+		return -EINVAL;
+	}
+
 	if (nomap) {
 		/*
 		 * If the memory is already reserved (by another region), we
@@ -146,6 +154,12 @@ static int __init early_init_dt_reserve_memory(phys_addr_t base,
 	return memblock_reserve(base, size);
 }
 
+void __init early_init_set_rsv_region_verifier(bool (*is_mem_reserved)(phys_addr_t base,
+								       phys_addr_t size))
+{
+	arch_is_region_reserved = is_mem_reserved;
+}
+
 /*
  * __reserved_mem_reserve_reg() - reserve all memory described in 'reg' property
  */
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index b8d6c0c20876..c7769323e720 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -65,6 +65,8 @@ extern void early_init_dt_check_for_usable_mem_range(void);
 extern int early_init_dt_scan_chosen_stdout(void);
 extern void early_init_fdt_scan_reserved_mem(void);
 extern void early_init_fdt_reserve_self(void);
+extern void early_init_set_rsv_region_verifier(bool (*is_mem_reserved)(phys_addr_t base,
+								       phys_addr_t size));
 extern void early_init_dt_add_memory_arch(u64 base, u64 size);
 extern u64 dt_mem_next_cell(int s, const __be32 **cellp);
 
@@ -89,6 +91,8 @@ static inline void early_init_dt_check_for_usable_mem_range(void) {}
 static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }
 static inline void early_init_fdt_scan_reserved_mem(void) {}
 static inline void early_init_fdt_reserve_self(void) {}
+static inline void early_init_set_rsv_region_verifier(bool (*is_mem_reserved)(phys_addr_t base,
+									      phys_addr_t size)) {};
 static inline const char *of_flat_dt_get_machine_name(void) { return NULL; }
 static inline void unflatten_device_tree(void) {}
 static inline void unflatten_and_copy_device_tree(void) {}
-- 
2.49.0.805.g082f7c87e0-goog