Commit 4ab21506 authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

arm64: Add memory hotplug support 



Wire up the basic support for hot-adding memory. Since memory hotplug
is fairly tightly coupled to sparsemem, we tweak pfn_valid() to also
cross-check the presence of a section in the manner of the generic
implementation, before falling back to memblock to check for no-map
regions within a present section as before. By having arch_add_memory(()
create the linear mapping first, this then makes everything work in the
way that __add_section() expects.

We expect hotplug to be ACPI-driven, so the swapper_pg_dir updates
should be safe from races by virtue of the global device hotplug lock.

Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 6e4ede69

arch/arm64/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -261,6 +261,9 @@ config ZONE_DMA32 
config HAVE_GENERIC_GUP

	def_bool y



config ARCH_ENABLE_MEMORY_HOTPLUG

	def_bool y



config SMP

	def_bool y

arch/arm64/mm/init.c

+8 −0
Original line number Diff line number Diff line
@@ -291,6 +291,14 @@ int pfn_valid(unsigned long pfn) 


	if ((addr >> PAGE_SHIFT) != pfn)

		return 0;



#ifdef CONFIG_SPARSEMEM

	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)

		return 0;



	if (!valid_section(__nr_to_section(pfn_to_section_nr(pfn))))

		return 0;

#endif

	return memblock_is_map_memory(addr);

}

EXPORT_SYMBOL(pfn_valid);

arch/arm64/mm/mmu.c

+17 −0
Original line number Diff line number Diff line
@@ -1046,3 +1046,20 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr) 
	pmd_free(NULL, table);

	return 1;

}



#ifdef CONFIG_MEMORY_HOTPLUG

int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,

		    bool want_memblock)

{

	int flags = 0;



	if (rodata_full || debug_pagealloc_enabled())

		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;



	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),

			     size, PAGE_KERNEL, pgd_pgtable_alloc, flags);



	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,

			   altmap, want_memblock);

}

#endif

arch/arm64/mm/numa.c

+10 −0
Original line number Diff line number Diff line
@@ -466,3 +466,13 @@ void __init arm64_numa_init(void) 


	numa_init(dummy_numa_init);

}



/*

 * We hope that we will be hotplugging memory on nodes we already know about,

 * such that acpi_get_node() succeeds and we never fall back to this...

 */

int memory_add_physaddr_to_nid(u64 addr)

{

	pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", addr);

	return 0;

}

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