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riscv: mm: Add memory hotplugging support
For an architecture to support memory hotplugging, a couple of callbacks needs to be implemented: arch_add_memory() This callback is responsible for adding the physical memory into the direct map, and call into the memory hotplugging generic code via __add_pages() that adds the corresponding struct page entries, and updates the vmemmap mapping. arch_remove_memory() This is the inverse of the callback above. vmemmap_free() This function tears down the vmemmap mappings (if CONFIG_SPARSEMEM_VMEMMAP is enabled), and also deallocates the backing vmemmap pages. Note that for persistent memory, an alternative allocator for the backing pages can be used; The vmem_altmap. This means that when the backing pages are cleared, extra care is needed so that the correct deallocation method is used. arch_get_mappable_range() This functions returns the PA range that the direct map can map. Used by the MHP internals for sanity checks. The page table unmap/teardown functions are heavily based on code from the x86 tree. The same remove_pgd_mapping() function is used in both vmemmap_free() and arch_remove_memory(), but in the latter function the backing pages are not removed. Signed-off-by: Björn Töpel <bjorn@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240605114100.315918-7-bjorn@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Björn Töpel
Palmer Dabbelt
parent
6e6c5e21b8
commit
c75a74f4ba
@ -1533,3 +1533,270 @@ struct execmem_info __init *execmem_arch_setup(void)
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}
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#endif /* CONFIG_MMU */
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#endif /* CONFIG_EXECMEM */
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#ifdef CONFIG_MEMORY_HOTPLUG
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static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd)
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{
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struct page *page = pmd_page(*pmd);
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struct ptdesc *ptdesc = page_ptdesc(page);
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pte_t *pte;
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int i;
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for (i = 0; i < PTRS_PER_PTE; i++) {
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pte = pte_start + i;
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if (!pte_none(*pte))
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return;
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}
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pagetable_pte_dtor(ptdesc);
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if (PageReserved(page))
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free_reserved_page(page);
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else
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pagetable_free(ptdesc);
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pmd_clear(pmd);
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}
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static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud)
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{
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struct page *page = pud_page(*pud);
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struct ptdesc *ptdesc = page_ptdesc(page);
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pmd_t *pmd;
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int i;
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for (i = 0; i < PTRS_PER_PMD; i++) {
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pmd = pmd_start + i;
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if (!pmd_none(*pmd))
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return;
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}
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pagetable_pmd_dtor(ptdesc);
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if (PageReserved(page))
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free_reserved_page(page);
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else
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pagetable_free(ptdesc);
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pud_clear(pud);
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}
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static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d)
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{
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struct page *page = p4d_page(*p4d);
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pud_t *pud;
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int i;
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for (i = 0; i < PTRS_PER_PUD; i++) {
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pud = pud_start + i;
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if (!pud_none(*pud))
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return;
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}
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if (PageReserved(page))
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free_reserved_page(page);
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else
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free_pages((unsigned long)page_address(page), 0);
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p4d_clear(p4d);
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}
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static void __meminit free_vmemmap_storage(struct page *page, size_t size,
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struct vmem_altmap *altmap)
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{
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int order = get_order(size);
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if (altmap) {
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vmem_altmap_free(altmap, size >> PAGE_SHIFT);
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return;
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}
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if (PageReserved(page)) {
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unsigned int nr_pages = 1 << order;
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while (nr_pages--)
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free_reserved_page(page++);
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return;
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}
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free_pages((unsigned long)page_address(page), order);
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}
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static void __meminit remove_pte_mapping(pte_t *pte_base, unsigned long addr, unsigned long end,
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bool is_vmemmap, struct vmem_altmap *altmap)
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{
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unsigned long next;
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pte_t *ptep, pte;
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for (; addr < end; addr = next) {
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next = (addr + PAGE_SIZE) & PAGE_MASK;
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if (next > end)
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next = end;
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ptep = pte_base + pte_index(addr);
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pte = ptep_get(ptep);
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if (!pte_present(*ptep))
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continue;
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pte_clear(&init_mm, addr, ptep);
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if (is_vmemmap)
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free_vmemmap_storage(pte_page(pte), PAGE_SIZE, altmap);
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}
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}
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static void __meminit remove_pmd_mapping(pmd_t *pmd_base, unsigned long addr, unsigned long end,
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bool is_vmemmap, struct vmem_altmap *altmap)
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{
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unsigned long next;
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pte_t *pte_base;
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pmd_t *pmdp, pmd;
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for (; addr < end; addr = next) {
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next = pmd_addr_end(addr, end);
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pmdp = pmd_base + pmd_index(addr);
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pmd = pmdp_get(pmdp);
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if (!pmd_present(pmd))
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continue;
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if (pmd_leaf(pmd)) {
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pmd_clear(pmdp);
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if (is_vmemmap)
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free_vmemmap_storage(pmd_page(pmd), PMD_SIZE, altmap);
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continue;
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}
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pte_base = (pte_t *)pmd_page_vaddr(*pmdp);
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remove_pte_mapping(pte_base, addr, next, is_vmemmap, altmap);
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free_pte_table(pte_base, pmdp);
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}
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}
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static void __meminit remove_pud_mapping(pud_t *pud_base, unsigned long addr, unsigned long end,
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bool is_vmemmap, struct vmem_altmap *altmap)
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{
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unsigned long next;
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pud_t *pudp, pud;
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pmd_t *pmd_base;
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for (; addr < end; addr = next) {
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next = pud_addr_end(addr, end);
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pudp = pud_base + pud_index(addr);
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pud = pudp_get(pudp);
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if (!pud_present(pud))
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continue;
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if (pud_leaf(pud)) {
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if (pgtable_l4_enabled) {
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pud_clear(pudp);
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if (is_vmemmap)
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free_vmemmap_storage(pud_page(pud), PUD_SIZE, altmap);
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}
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continue;
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}
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pmd_base = pmd_offset(pudp, 0);
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remove_pmd_mapping(pmd_base, addr, next, is_vmemmap, altmap);
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if (pgtable_l4_enabled)
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free_pmd_table(pmd_base, pudp);
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}
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}
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static void __meminit remove_p4d_mapping(p4d_t *p4d_base, unsigned long addr, unsigned long end,
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bool is_vmemmap, struct vmem_altmap *altmap)
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{
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unsigned long next;
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p4d_t *p4dp, p4d;
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pud_t *pud_base;
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for (; addr < end; addr = next) {
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next = p4d_addr_end(addr, end);
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p4dp = p4d_base + p4d_index(addr);
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p4d = p4dp_get(p4dp);
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if (!p4d_present(p4d))
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continue;
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if (p4d_leaf(p4d)) {
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if (pgtable_l5_enabled) {
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p4d_clear(p4dp);
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if (is_vmemmap)
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free_vmemmap_storage(p4d_page(p4d), P4D_SIZE, altmap);
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}
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continue;
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}
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pud_base = pud_offset(p4dp, 0);
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remove_pud_mapping(pud_base, addr, next, is_vmemmap, altmap);
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if (pgtable_l5_enabled)
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free_pud_table(pud_base, p4dp);
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}
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}
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static void __meminit remove_pgd_mapping(unsigned long va, unsigned long end, bool is_vmemmap,
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struct vmem_altmap *altmap)
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{
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unsigned long addr, next;
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p4d_t *p4d_base;
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pgd_t *pgd;
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for (addr = va; addr < end; addr = next) {
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next = pgd_addr_end(addr, end);
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pgd = pgd_offset_k(addr);
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if (!pgd_present(*pgd))
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continue;
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if (pgd_leaf(*pgd))
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continue;
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p4d_base = p4d_offset(pgd, 0);
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remove_p4d_mapping(p4d_base, addr, next, is_vmemmap, altmap);
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}
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flush_tlb_all();
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}
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static void __meminit remove_linear_mapping(phys_addr_t start, u64 size)
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{
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unsigned long va = (unsigned long)__va(start);
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unsigned long end = (unsigned long)__va(start + size);
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remove_pgd_mapping(va, end, false, NULL);
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}
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struct range arch_get_mappable_range(void)
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{
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struct range mhp_range;
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mhp_range.start = __pa(PAGE_OFFSET);
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mhp_range.end = __pa(PAGE_END - 1);
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return mhp_range;
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}
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int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params)
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{
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int ret = 0;
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create_linear_mapping_range(start, start + size, 0, ¶ms->pgprot);
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ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, params);
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if (ret) {
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remove_linear_mapping(start, size);
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goto out;
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}
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max_pfn = PFN_UP(start + size);
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max_low_pfn = max_pfn;
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out:
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flush_tlb_all();
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return ret;
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}
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void __ref arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
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{
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__remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT, altmap);
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remove_linear_mapping(start, size);
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flush_tlb_all();
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}
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void __ref vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap)
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{
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remove_pgd_mapping(start, end, true, altmap);
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}
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#endif /* CONFIG_MEMORY_HOTPLUG */
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