Add a few functions to enable early HVO:
vmemmap_populate_hvo
vmemmap_undo_hvo
vmemmap_wrprotect_hvo
The populate and undo functions are expected to be used in early
init, from the sparse_init_nid_early() function. The wrprotect
function is to be used, potentially, later.
To implement these functions, mostly re-use the existing
compound pages vmemmap logic used by DAX. vmemmap_populate_address
has its argument changed a bit in this commit: the page structure
passed in to be reused in the mapping is replaced by a PFN and a
flag. The flag indicates whether an extra ref should be taken on
the vmemmap page containing the head page structure. Taking the
ref is appropriate to for DAX / ZONE_DEVICE, but not for HugeTLB
HVO.
The HugeTLB vmemmap optimization maps tail page structure pages
read-only. The vmemmap_wrprotect_hvo function that does this is
implemented separately, because it cannot be guaranteed that reserved
page structures will not be write accessed during memory initialization.
Even with CONFIG_DEFERRED_STRUCT_PAGE_INIT, they might still be
written to (if they are at the bottom of a zone). So,
vmemmap_populate_hvo leaves the tail page structure pages RW initially,
and then later during initialization, after memmap init is fully done,
vmemmap_wrprotect_hvo must be called to finish the job.
Subsequent commits will use these functions for early HugeTLB HVO.
Signed-off-by: Frank van der Linden <fvdl@xxxxxxxxxx>
---
include/linux/mm.h | 9 ++-
mm/sparse-vmemmap.c | 141 +++++++++++++++++++++++++++++++++++++++-----
2 files changed, 135 insertions(+), 15 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index df83653ed6e3..0463c062fd7a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3837,7 +3837,8 @@ p4d_t *vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node);
pud_t *vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node);
pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node);
pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
- struct vmem_altmap *altmap, struct page *reuse);
+ struct vmem_altmap *altmap, unsigned long ptpfn,
+ unsigned long flags);
void *vmemmap_alloc_block(unsigned long size, int node);
struct vmem_altmap;
void *vmemmap_alloc_block_buf(unsigned long size, int node,
@@ -3853,6 +3854,12 @@ int vmemmap_populate_hugepages(unsigned long start, unsigned long end,
int node, struct vmem_altmap *altmap);
int vmemmap_populate(unsigned long start, unsigned long end, int node,
struct vmem_altmap *altmap);
+int vmemmap_populate_hvo(unsigned long start, unsigned long end, int node,
+ unsigned long headsize);
+int vmemmap_undo_hvo(unsigned long start, unsigned long end, int node,
+ unsigned long headsize);
+void vmemmap_wrprotect_hvo(unsigned long start, unsigned long end, int node,
+ unsigned long headsize);
void vmemmap_populate_print_last(void);
#ifdef CONFIG_MEMORY_HOTPLUG
void vmemmap_free(unsigned long start, unsigned long end,
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 8751c46c35e4..bee22ca93654 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -30,6 +30,13 @@
#include <asm/dma.h>
#include <asm/pgalloc.h>
+#include <asm/tlbflush.h>
+
+/*
+ * Flags for vmemmap_populate_range and friends.
+ */
+/* Get a ref on the head page struct page, for ZONE_DEVICE compound pages */
+#define VMEMMAP_POPULATE_PAGEREF 0x0001
#include "internal.h"
@@ -144,17 +151,18 @@ void __meminit vmemmap_verify(pte_t *pte, int node,
pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
struct vmem_altmap *altmap,
- struct page *reuse)
+ unsigned long ptpfn, unsigned long flags)
{
pte_t *pte = pte_offset_kernel(pmd, addr);
if (pte_none(ptep_get(pte))) {
pte_t entry;
void *p;
- if (!reuse) {
+ if (!ptpfn) {
p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
if (!p)
return NULL;
+ ptpfn = PHYS_PFN(__pa(p));
} else {
/*
* When a PTE/PMD entry is freed from the init_mm
@@ -165,10 +173,10 @@ pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
* and through vmemmap_populate_compound_pages() when
* slab is available.
*/
- get_page(reuse);
- p = page_to_virt(reuse);
+ if (flags & VMEMMAP_POPULATE_PAGEREF)
+ get_page(pfn_to_page(ptpfn));
}
- entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
+ entry = pfn_pte(ptpfn, PAGE_KERNEL);
set_pte_at(&init_mm, addr, pte, entry);
}
return pte;
@@ -238,7 +246,8 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
struct vmem_altmap *altmap,
- struct page *reuse)
+ unsigned long ptpfn,
+ unsigned long flags)
{
pgd_t *pgd;
p4d_t *p4d;
@@ -258,7 +267,7 @@ static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
pmd = vmemmap_pmd_populate(pud, addr, node);
if (!pmd)
return NULL;
- pte = vmemmap_pte_populate(pmd, addr, node, altmap, reuse);
+ pte = vmemmap_pte_populate(pmd, addr, node, altmap, ptpfn, flags);
if (!pte)
return NULL;
vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
@@ -269,13 +278,15 @@ static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
static int __meminit vmemmap_populate_range(unsigned long start,
unsigned long end, int node,
struct vmem_altmap *altmap,
- struct page *reuse)
+ unsigned long ptpfn,
+ unsigned long flags)
{
unsigned long addr = start;
pte_t *pte;
for (; addr < end; addr += PAGE_SIZE) {
- pte = vmemmap_populate_address(addr, node, altmap, reuse);
+ pte = vmemmap_populate_address(addr, node, altmap,
+ ptpfn, flags);
if (!pte)
return -ENOMEM;
}
@@ -286,7 +297,107 @@ static int __meminit vmemmap_populate_range(unsigned long start,
int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
int node, struct vmem_altmap *altmap)
{
- return vmemmap_populate_range(start, end, node, altmap, NULL);
+ return vmemmap_populate_range(start, end, node, altmap, 0, 0);
+}
+
+/*
+ * Undo populate_hvo, and replace it with a normal base page mapping.
+ * Used in memory init in case a HVO mapping needs to be undone.
+ *
+ * This can happen when it is discovered that a memblock allocated
+ * hugetlb page spans multiple zones, which can only be verified
+ * after zones have been initialized.
+ *
+ * We know that:
+ * 1) The first @headsize / PAGE_SIZE vmemmap pages were individually
+ * allocated through memblock, and mapped.
+ *
+ * 2) The rest of the vmemmap pages are mirrors of the last head page.
+ */
+int __meminit vmemmap_undo_hvo(unsigned long addr, unsigned long end,
+ int node, unsigned long headsize)
+{
+ unsigned long maddr, pfn;
+ pte_t *pte;
+ int headpages;
+
+ /*
+ * Should only be called early in boot, so nothing will
+ * be accessing these page structures.
+ */
+ WARN_ON(!early_boot_irqs_disabled);
+
+ headpages = headsize >> PAGE_SHIFT;
+
+ /*
+ * Clear mirrored mappings for tail page structs.
+ */
+ for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
+ pte = virt_to_kpte(maddr);
+ pte_clear(&init_mm, maddr, pte);
+ }
+
+ /*
+ * Clear and free mappings for head page and first tail page
+ * structs.
+ */
+ for (maddr = addr; headpages-- > 0; maddr += PAGE_SIZE) {
+ pte = virt_to_kpte(maddr);
+ pfn = pte_pfn(ptep_get(pte));
+ pte_clear(&init_mm, maddr, pte);
+ memblock_phys_free(PFN_PHYS(pfn), PAGE_SIZE);
+ }
+
+ flush_tlb_kernel_range(addr, end);
+
+ return vmemmap_populate(addr, end, node, NULL);
+}
+
+/*
+ * Write protect the mirrored tail page structs for HVO. This will be
+ * called from the hugetlb code when gathering and initializing the
+ * memblock allocated gigantic pages. The write protect can't be
+ * done earlier, since it can't be guaranteed that the reserved
+ * page structures will not be written to during initialization,
+ * even if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled.
+ *
+ * The PTEs are known to exist, and nothing else should be touching
+ * these pages. The caller is responsible for any TLB flushing.
+ */
+void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end,
+ int node, unsigned long headsize)
+{
+ unsigned long maddr;
+ pte_t *pte;
+
+ for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
+ pte = virt_to_kpte(maddr);
+ ptep_set_wrprotect(&init_mm, maddr, pte);
+ }
+}
+
+/*
+ * Populate vmemmap pages HVO-style. The first page contains the head
+ * page and needed tail pages, the other ones are mirrors of the first
+ * page.
+ */
+int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
+ int node, unsigned long headsize)
+{
+ pte_t *pte;
+ unsigned long maddr;
+
+ for (maddr = addr; maddr < addr + headsize; maddr += PAGE_SIZE) {
+ pte = vmemmap_populate_address(maddr, node, NULL, 0, 0);
+ if (!pte)
+ return -ENOMEM;
+ }
+
+ /*
+ * Reuse the last page struct page mapped above for the rest.
+ */
+ return vmemmap_populate_range(maddr, end, node, NULL,
+ pte_pfn(ptep_get(pte)), 0);
}
void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
@@ -409,7 +520,8 @@ static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
* with just tail struct pages.
*/
return vmemmap_populate_range(start, end, node, NULL,
- pte_page(ptep_get(pte)));
+ pte_pfn(ptep_get(pte)),
+ VMEMMAP_POPULATE_PAGEREF);
}
size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
@@ -417,13 +529,13 @@ static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
unsigned long next, last = addr + size;
/* Populate the head page vmemmap page */
- pte = vmemmap_populate_address(addr, node, NULL, NULL);
+ pte = vmemmap_populate_address(addr, node, NULL, 0, 0);
if (!pte)
return -ENOMEM;
/* Populate the tail pages vmemmap page */
next = addr + PAGE_SIZE;
- pte = vmemmap_populate_address(next, node, NULL, NULL);
+ pte = vmemmap_populate_address(next, node, NULL, 0, 0);
if (!pte)
return -ENOMEM;
@@ -433,7 +545,8 @@ static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
*/
next += PAGE_SIZE;
rc = vmemmap_populate_range(next, last, node, NULL,
- pte_page(ptep_get(pte)));
+ pte_pfn(ptep_get(pte)),
+ VMEMMAP_POPULATE_PAGEREF);
if (rc)
return -ENOMEM;
}
--
2.48.1.262.g85cc9f2d1e-goog
