From c75a74f4ba19c904c0ae1e011ae2568449409ae4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Wed, 5 Jun 2024 13:40:49 +0200 Subject: [PATCH] riscv: mm: Add memory hotplugging support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20240605114100.315918-7-bjorn@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/init.c | 267 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 267 insertions(+) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 691600c96eadf7..201ebb190b1035 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -1533,3 +1533,270 @@ struct execmem_info __init *execmem_arch_setup(void) } #endif /* CONFIG_MMU */ #endif /* CONFIG_EXECMEM */ + +#ifdef CONFIG_MEMORY_HOTPLUG +static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd) +{ + struct page *page = pmd_page(*pmd); + struct ptdesc *ptdesc = page_ptdesc(page); + pte_t *pte; + int i; + + for (i = 0; i < PTRS_PER_PTE; i++) { + pte = pte_start + i; + if (!pte_none(*pte)) + return; + } + + pagetable_pte_dtor(ptdesc); + if (PageReserved(page)) + free_reserved_page(page); + else + pagetable_free(ptdesc); + pmd_clear(pmd); +} + +static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud) +{ + struct page *page = pud_page(*pud); + struct ptdesc *ptdesc = page_ptdesc(page); + pmd_t *pmd; + int i; + + for (i = 0; i < PTRS_PER_PMD; i++) { + pmd = pmd_start + i; + if (!pmd_none(*pmd)) + return; + } + + pagetable_pmd_dtor(ptdesc); + if (PageReserved(page)) + free_reserved_page(page); + else + pagetable_free(ptdesc); + pud_clear(pud); +} + +static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d) +{ + struct page *page = p4d_page(*p4d); + pud_t *pud; + int i; + + for (i = 0; i < PTRS_PER_PUD; i++) { + pud = pud_start + i; + if (!pud_none(*pud)) + return; + } + + if (PageReserved(page)) + free_reserved_page(page); + else + free_pages((unsigned long)page_address(page), 0); + p4d_clear(p4d); +} + +static void __meminit free_vmemmap_storage(struct page *page, size_t size, + struct vmem_altmap *altmap) +{ + int order = get_order(size); + + if (altmap) { + vmem_altmap_free(altmap, size >> PAGE_SHIFT); + return; + } + + if (PageReserved(page)) { + unsigned int nr_pages = 1 << order; + + while (nr_pages--) + free_reserved_page(page++); + return; + } + + free_pages((unsigned long)page_address(page), order); +} + +static void __meminit remove_pte_mapping(pte_t *pte_base, unsigned long addr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pte_t *ptep, pte; + + for (; addr < end; addr = next) { + next = (addr + PAGE_SIZE) & PAGE_MASK; + if (next > end) + next = end; + + ptep = pte_base + pte_index(addr); + pte = ptep_get(ptep); + if (!pte_present(*ptep)) + continue; + + pte_clear(&init_mm, addr, ptep); + if (is_vmemmap) + free_vmemmap_storage(pte_page(pte), PAGE_SIZE, altmap); + } +} + +static void __meminit remove_pmd_mapping(pmd_t *pmd_base, unsigned long addr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pte_t *pte_base; + pmd_t *pmdp, pmd; + + for (; addr < end; addr = next) { + next = pmd_addr_end(addr, end); + pmdp = pmd_base + pmd_index(addr); + pmd = pmdp_get(pmdp); + if (!pmd_present(pmd)) + continue; + + if (pmd_leaf(pmd)) { + pmd_clear(pmdp); + if (is_vmemmap) + free_vmemmap_storage(pmd_page(pmd), PMD_SIZE, altmap); + continue; + } + + pte_base = (pte_t *)pmd_page_vaddr(*pmdp); + remove_pte_mapping(pte_base, addr, next, is_vmemmap, altmap); + free_pte_table(pte_base, pmdp); + } +} + +static void __meminit remove_pud_mapping(pud_t *pud_base, unsigned long addr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + pud_t *pudp, pud; + pmd_t *pmd_base; + + for (; addr < end; addr = next) { + next = pud_addr_end(addr, end); + pudp = pud_base + pud_index(addr); + pud = pudp_get(pudp); + if (!pud_present(pud)) + continue; + + if (pud_leaf(pud)) { + if (pgtable_l4_enabled) { + pud_clear(pudp); + if (is_vmemmap) + free_vmemmap_storage(pud_page(pud), PUD_SIZE, altmap); + } + continue; + } + + pmd_base = pmd_offset(pudp, 0); + remove_pmd_mapping(pmd_base, addr, next, is_vmemmap, altmap); + + if (pgtable_l4_enabled) + free_pmd_table(pmd_base, pudp); + } +} + +static void __meminit remove_p4d_mapping(p4d_t *p4d_base, unsigned long addr, unsigned long end, + bool is_vmemmap, struct vmem_altmap *altmap) +{ + unsigned long next; + p4d_t *p4dp, p4d; + pud_t *pud_base; + + for (; addr < end; addr = next) { + next = p4d_addr_end(addr, end); + p4dp = p4d_base + p4d_index(addr); + p4d = p4dp_get(p4dp); + if (!p4d_present(p4d)) + continue; + + if (p4d_leaf(p4d)) { + if (pgtable_l5_enabled) { + p4d_clear(p4dp); + if (is_vmemmap) + free_vmemmap_storage(p4d_page(p4d), P4D_SIZE, altmap); + } + continue; + } + + pud_base = pud_offset(p4dp, 0); + remove_pud_mapping(pud_base, addr, next, is_vmemmap, altmap); + + if (pgtable_l5_enabled) + free_pud_table(pud_base, p4dp); + } +} + +static void __meminit remove_pgd_mapping(unsigned long va, unsigned long end, bool is_vmemmap, + struct vmem_altmap *altmap) +{ + unsigned long addr, next; + p4d_t *p4d_base; + pgd_t *pgd; + + for (addr = va; addr < end; addr = next) { + next = pgd_addr_end(addr, end); + pgd = pgd_offset_k(addr); + + if (!pgd_present(*pgd)) + continue; + + if (pgd_leaf(*pgd)) + continue; + + p4d_base = p4d_offset(pgd, 0); + remove_p4d_mapping(p4d_base, addr, next, is_vmemmap, altmap); + } + + flush_tlb_all(); +} + +static void __meminit remove_linear_mapping(phys_addr_t start, u64 size) +{ + unsigned long va = (unsigned long)__va(start); + unsigned long end = (unsigned long)__va(start + size); + + remove_pgd_mapping(va, end, false, NULL); +} + +struct range arch_get_mappable_range(void) +{ + struct range mhp_range; + + mhp_range.start = __pa(PAGE_OFFSET); + mhp_range.end = __pa(PAGE_END - 1); + return mhp_range; +} + +int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) +{ + int ret = 0; + + create_linear_mapping_range(start, start + size, 0, ¶ms->pgprot); + ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, params); + if (ret) { + remove_linear_mapping(start, size); + goto out; + } + + max_pfn = PFN_UP(start + size); + max_low_pfn = max_pfn; + + out: + flush_tlb_all(); + return ret; +} + +void __ref arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap) +{ + __remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT, altmap); + remove_linear_mapping(start, size); + flush_tlb_all(); +} + +void __ref vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap) +{ + remove_pgd_mapping(start, end, true, altmap); +} +#endif /* CONFIG_MEMORY_HOTPLUG */