This enables vmemmap_populate() and vmemmap_free() functions to incorporate
struct vmem_altmap based device memory allocation and free requests. With
this device memory with specific atlmap configuration can be hot plugged
and hot removed as ZONE_DEVICE memory on arm64 platforms.

Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: linux-arm-ker...@lists.infradead.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Anshuman Khandual <anshuman.khand...@arm.com>
---
 arch/arm64/mm/mmu.c | 57 ++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 39e18d1..8867bbd 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -735,15 +735,26 @@ int kern_addr_valid(unsigned long addr)
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-static void free_hotplug_page_range(struct page *page, size_t size)
+static void free_hotplug_page_range(struct page *page, size_t size,
+                                   struct vmem_altmap *altmap)
 {
-       WARN_ON(!page || PageReserved(page));
-       free_pages((unsigned long)page_address(page), get_order(size));
+       if (altmap) {
+               /*
+                * vmemmap_populate() creates vmemmap mapping either at pte
+                * or pmd level. Unmapping request at any other level would
+                * be a problem.
+                */
+               WARN_ON((size != PAGE_SIZE) && (size != PMD_SIZE));
+               vmem_altmap_free(altmap, size >> PAGE_SHIFT);
+       } else {
+               WARN_ON(!page || PageReserved(page));
+               free_pages((unsigned long)page_address(page), get_order(size));
+       }
 }
 
 static void free_hotplug_pgtable_page(struct page *page)
 {
-       free_hotplug_page_range(page, PAGE_SIZE);
+       free_hotplug_page_range(page, PAGE_SIZE, NULL);
 }
 
 static void free_pte_table(pmd_t *pmdp, unsigned long addr)
@@ -807,7 +818,8 @@ static void free_pud_table(pgd_t *pgdp, unsigned long addr)
 }
 
 static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,
-                                   unsigned long end, bool sparse_vmap)
+                                   unsigned long end, bool sparse_vmap,
+                                   struct vmem_altmap *altmap)
 {
        struct page *page;
        pte_t *ptep, pte;
@@ -823,12 +835,13 @@ static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned 
long addr,
                pte_clear(&init_mm, addr, ptep);
                flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
                if (sparse_vmap)
-                       free_hotplug_page_range(page, PAGE_SIZE);
+                       free_hotplug_page_range(page, PAGE_SIZE, altmap);
        } while (addr += PAGE_SIZE, addr < end);
 }
 
 static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr,
-                                   unsigned long end, bool sparse_vmap)
+                                   unsigned long end, bool sparse_vmap,
+                                   struct vmem_altmap *altmap)
 {
        unsigned long next;
        struct page *page;
@@ -847,16 +860,17 @@ static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned 
long addr,
                        pmd_clear(pmdp);
                        flush_tlb_kernel_range(addr, next);
                        if (sparse_vmap)
-                               free_hotplug_page_range(page, PMD_SIZE);
+                               free_hotplug_page_range(page, PMD_SIZE, altmap);
                        continue;
                }
                WARN_ON(!pmd_table(pmd));
-               unmap_hotplug_pte_range(pmdp, addr, next, sparse_vmap);
+               unmap_hotplug_pte_range(pmdp, addr, next, sparse_vmap, altmap);
        } while (addr = next, addr < end);
 }
 
 static void unmap_hotplug_pud_range(pgd_t *pgdp, unsigned long addr,
-                                   unsigned long end, bool sparse_vmap)
+                                   unsigned long end, bool sparse_vmap,
+                                   struct vmem_altmap *altmap)
 {
        unsigned long next;
        struct page *page;
@@ -875,16 +889,16 @@ static void unmap_hotplug_pud_range(pgd_t *pgdp, unsigned 
long addr,
                        pud_clear(pudp);
                        flush_tlb_kernel_range(addr, next);
                        if (sparse_vmap)
-                               free_hotplug_page_range(page, PUD_SIZE);
+                               free_hotplug_page_range(page, PUD_SIZE, altmap);
                        continue;
                }
                WARN_ON(!pud_table(pud));
-               unmap_hotplug_pmd_range(pudp, addr, next, sparse_vmap);
+               unmap_hotplug_pmd_range(pudp, addr, next, sparse_vmap, altmap);
        } while (addr = next, addr < end);
 }
 
 static void unmap_hotplug_range(unsigned long addr, unsigned long end,
-                               bool sparse_vmap)
+                               bool sparse_vmap, struct vmem_altmap *altmap)
 {
        unsigned long next;
        pgd_t *pgdp, pgd;
@@ -897,7 +911,7 @@ static void unmap_hotplug_range(unsigned long addr, 
unsigned long end,
                        continue;
 
                WARN_ON(!pgd_present(pgd));
-               unmap_hotplug_pud_range(pgdp, addr, next, sparse_vmap);
+               unmap_hotplug_pud_range(pgdp, addr, next, sparse_vmap, altmap);
        } while (addr = next, addr < end);
 }
 
@@ -970,9 +984,9 @@ static void free_empty_tables(unsigned long addr, unsigned 
long end)
 }
 
 static void remove_pagetable(unsigned long start, unsigned long end,
-                            bool sparse_vmap)
+                            bool sparse_vmap, struct vmem_altmap *altmap)
 {
-       unmap_hotplug_range(start, end, sparse_vmap);
+       unmap_hotplug_range(start, end, sparse_vmap, altmap);
        free_empty_tables(start, end);
 }
 #endif
@@ -982,7 +996,7 @@ static void remove_pagetable(unsigned long start, unsigned 
long end,
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int 
node,
                struct vmem_altmap *altmap)
 {
-       return vmemmap_populate_basepages(start, end, node, NULL);
+       return vmemmap_populate_basepages(start, end, node, altmap);
 }
 #else  /* !ARM64_SWAPPER_USES_SECTION_MAPS */
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int 
node,
@@ -1009,7 +1023,10 @@ int __meminit vmemmap_populate(unsigned long start, 
unsigned long end, int node,
                if (pmd_none(READ_ONCE(*pmdp))) {
                        void *p = NULL;
 
-                       p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+                       if (altmap)
+                               p = altmap_alloc_block_buf(PMD_SIZE, altmap);
+                       else
+                               p = vmemmap_alloc_block_buf(PMD_SIZE, node);
                        if (!p)
                                return -ENOMEM;
 
@@ -1043,7 +1060,7 @@ void vmemmap_free(unsigned long start, unsigned long end,
         * given vmemmap range being hot-removed. Just unmap and free the
         * range instead.
         */
-       unmap_hotplug_range(start, end, true);
+       unmap_hotplug_range(start, end, true, altmap);
 #endif
 }
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
@@ -1336,7 +1353,7 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned 
long start, u64 size)
        unsigned long end = start + size;
 
        WARN_ON(pgdir != init_mm.pgd);
-       remove_pagetable(start, end, false);
+       remove_pagetable(start, end, false, NULL);
 }
 
 int arch_add_memory(int nid, u64 start, u64 size,
-- 
2.7.4

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