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: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Robin Murphy 2018-12-11 18:48:48 +00:00 committed by Will Deacon
parent 6e4ede698d
commit 4ab2150615
4 changed files with 38 additions and 0 deletions

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@ -261,6 +261,9 @@ config ZONE_DMA32
config HAVE_GENERIC_GUP config HAVE_GENERIC_GUP
def_bool y def_bool y
config ARCH_ENABLE_MEMORY_HOTPLUG
def_bool y
config SMP config SMP
def_bool y def_bool y

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@ -291,6 +291,14 @@ int pfn_valid(unsigned long pfn)
if ((addr >> PAGE_SHIFT) != pfn) if ((addr >> PAGE_SHIFT) != pfn)
return 0; 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); return memblock_is_map_memory(addr);
} }
EXPORT_SYMBOL(pfn_valid); EXPORT_SYMBOL(pfn_valid);

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@ -1046,3 +1046,20 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
pmd_free(NULL, table); pmd_free(NULL, table);
return 1; 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

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@ -466,3 +466,13 @@ void __init arm64_numa_init(void)
numa_init(dummy_numa_init); 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;
}