LoongArch: add sparse memory vmemmap support

Add sparse memory vmemmap support for LoongArch.  SPARSEMEM_VMEMMAP uses a
virtually mapped memmap to optimise pfn_to_page and page_to_pfn
operations.  This is the most efficient option when sufficient kernel
resources are available.

Link: https://lkml.kernel.org/r/20221027125253.3458989-3-chenhuacai@loongson.cn
Signed-off-by: Min Zhou <zhoumin@loongson.cn>
Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Cc: Xuerui Wang <kernel@xen0n.name>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 69 insertions, 3 deletions

diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 080061793c85..451d93667bcc 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -22,7 +22,7 @@
 #include <linux/pfn.h>
 #include <linux/hardirq.h>
 #include <linux/gfp.h>
-#include <linux/initrd.h>
+#include <linux/hugetlb.h>
 #include <linux/mmzone.h>
 
 #include <asm/asm-offsets.h>
@@ -152,6 +152,72 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
 #endif
 
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+static int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
+						int node, struct vmem_altmap *altmap)
+{
+	unsigned long addr = start;
+	unsigned long next;
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	for (addr = start; addr < end; addr = next) {
+		next = pmd_addr_end(addr, end);
+
+		pgd = vmemmap_pgd_populate(addr, node);
+		if (!pgd)
+			return -ENOMEM;
+		p4d = vmemmap_p4d_populate(pgd, addr, node);
+		if (!p4d)
+			return -ENOMEM;
+		pud = vmemmap_pud_populate(p4d, addr, node);
+		if (!pud)
+			return -ENOMEM;
+
+		pmd = pmd_offset(pud, addr);
+		if (pmd_none(*pmd)) {
+			void *p = NULL;
+
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node, NULL);
+			if (p) {
+				pmd_t entry;
+
+				entry = pfn_pmd(virt_to_pfn(p), PAGE_KERNEL);
+				pmd_val(entry) |= _PAGE_HUGE | _PAGE_HGLOBAL;
+				set_pmd_at(&init_mm, addr, pmd, entry);
+
+				continue;
+			}
+		} else if (pmd_val(*pmd) & _PAGE_HUGE) {
+			vmemmap_verify((pte_t *)pmd, node, addr, next);
+			continue;
+		}
+		if (vmemmap_populate_basepages(addr, next, node, NULL))
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+int __meminit vmemmap_populate(unsigned long start, unsigned long end,
+			       int node, struct vmem_altmap *altmap)
+{
+#if CONFIG_PGTABLE_LEVELS == 2
+	return vmemmap_populate_basepages(start, end, node, NULL);
+#else
+	return vmemmap_populate_hugepages(start, end, node, NULL);
+#endif
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap)
+{
+}
+#endif
+#endif
+
 static pte_t *fixmap_pte(unsigned long addr)
 {
 	pgd_t *pgd;
@@ -168,7 +234,7 @@ static pte_t *fixmap_pte(unsigned long addr)
 		new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
 		pgd_populate(&init_mm, pgd, new);
 #ifndef __PAGETABLE_PUD_FOLDED
-		pud_init((unsigned long)new, (unsigned long)invalid_pmd_table);
+		pud_init(new);
 #endif
 	}
 
@@ -179,7 +245,7 @@ static pte_t *fixmap_pte(unsigned long addr)
 		new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
 		pud_populate(&init_mm, pud, new);
 #ifndef __PAGETABLE_PMD_FOLDED
-		pmd_init((unsigned long)new, (unsigned long)invalid_pte_table);
+		pmd_init(new);
 #endif
 	}