riscv: acpi: Enable ARCH_HAS_ACPI_TABLE_UPGRADE

Implement the various required hooks and enable
ARCH_HAS_ACPI_TABLE_UPGRADE to allow use for ACPI_TABLE_UPGRADE, which
is useful for debugging ACPI table problems.

The implementation is based on arm64's of the same feature due to the
similarities of the requirements of the two platforms.

Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Link: https://patch.msgid.link/20260616-riscv-acpi-table-upgrade-v1-2-45902d2dedf9@iscas.ac.cn
[pjw@kernel.org: updated to apply]
Signed-off-by: Paul Walmsley <pjw@kernel.org>

arch/riscv/Kconfig

@@ -23,6 +23,7 @@ config RISCV
 	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM_VMEMMAP
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
+	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_CC_CAN_LINK
 	select ARCH_HAS_CURRENT_STACK_POINTER

arch/riscv/include/asm/acpi.h

@@ -92,4 +92,6 @@ void acpi_map_cpus_to_nodes(void);
 static inline void acpi_map_cpus_to_nodes(void) { }
 #endif /* CONFIG_ACPI_NUMA */
 
+#define ACPI_TABLE_UPGRADE_MAX_PHYS MEMBLOCK_ALLOC_ACCESSIBLE
+
 #endif /*_ASM_ACPI_H*/

arch/riscv/kernel/acpi.c

@@ -353,3 +353,8 @@ int acpi_get_cpu_uid(unsigned int cpu, u32 *uid)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(acpi_get_cpu_uid);
+
+void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
+{
+	memblock_mark_nomap(addr, size);
+}

arch/riscv/kernel/setup.c

@@ -321,6 +321,8 @@ void __init setup_arch(char **cmdline_p)
 	efi_init();
 	paging_init();
 
+	acpi_table_upgrade();
+
 	/* Parse the ACPI tables for possible boot-time configuration */
 	acpi_boot_table_init();