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>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 47c1f21e81dca7d4b1abeb2ba4fca203215597c9..e9af113c572f0133010ec4a43f6cfc87da4fa4ae 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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
 

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 6cde00554e9bbfa6151544bdc29196f560de81f2..4bfe0fc9edac66801b4758dfe98467392a5c4b45 100644 (file)
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -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);

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 674c409a8ce4e2b925df76bbbe81bc33a02f20f4..da513a1facf4fc4f1c45ecaab82321e5a1d1787f 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -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

diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 27a31efd9e8e9ba569651961e325c3e2c6c5b32f..ae34e3a1cef1c87eaedf28081bbdcd85bfceb86f 100644 (file)
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -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;
+}