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![Oliver O'Halloran](/assets/img/avatar_default.png)
The "altmap" is used to provide a pool of memory that is reserved for
the vmemmap backing of hot-plugged memory. This is useful when adding
large amount of ZONE_DEVICE memory to a system with a limited amount of
normal memory.
On ppc64 we use huge pages to map the vmemmap which requires the backing
storage to be contigious and aligned to the hugepage size. The altmap
implementation allows for the altmap provider to reserve a few PFNs at
the start of the range for it's own uses and when this occurs the
first chunk of the altmap is not usable for hugepage mappings. On hash
there is no sane way to fall back to a normal sized page mapping so we
fail the allocation. This results in memory hotplug failing with
ENOMEM when the new range doesn't fall into an existing vmemmap block.
This patch handles this case by falling back to using system memory
rather than failing if we cannot allocate from the altmap. This
fallback should only ever be used for the first vmemmap block so it
should not cause excess memory consumption.
Fixes: 7b73d978a5
("mm: pass the vmem_altmap to vmemmap_populate")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
412 lines
11 KiB
C
412 lines
11 KiB
C
/*
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* PowerPC version
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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*
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* Derived from "arch/i386/mm/init.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* Dave Engebretsen <engebret@us.ibm.com>
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* Rework for PPC64 port.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#undef DEBUG
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/stddef.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/highmem.h>
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#include <linux/idr.h>
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#include <linux/nodemask.h>
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#include <linux/module.h>
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#include <linux/poison.h>
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#include <linux/memblock.h>
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#include <linux/hugetlb.h>
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#include <linux/slab.h>
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#include <linux/of_fdt.h>
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#include <linux/libfdt.h>
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#include <linux/memremap.h>
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#include <asm/pgalloc.h>
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#include <asm/page.h>
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#include <asm/prom.h>
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#include <asm/rtas.h>
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#include <asm/io.h>
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#include <asm/mmu_context.h>
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#include <asm/pgtable.h>
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#include <asm/mmu.h>
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#include <linux/uaccess.h>
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#include <asm/smp.h>
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#include <asm/machdep.h>
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#include <asm/tlb.h>
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#include <asm/eeh.h>
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#include <asm/processor.h>
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#include <asm/mmzone.h>
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#include <asm/cputable.h>
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#include <asm/sections.h>
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#include <asm/iommu.h>
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#include <asm/vdso.h>
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#include "mmu_decl.h"
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phys_addr_t memstart_addr = ~0;
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EXPORT_SYMBOL_GPL(memstart_addr);
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phys_addr_t kernstart_addr;
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EXPORT_SYMBOL_GPL(kernstart_addr);
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#ifdef CONFIG_SPARSEMEM_VMEMMAP
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/*
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* Given an address within the vmemmap, determine the pfn of the page that
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* represents the start of the section it is within. Note that we have to
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* do this by hand as the proffered address may not be correctly aligned.
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* Subtraction of non-aligned pointers produces undefined results.
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*/
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static unsigned long __meminit vmemmap_section_start(unsigned long page)
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{
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unsigned long offset = page - ((unsigned long)(vmemmap));
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/* Return the pfn of the start of the section. */
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return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
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}
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/*
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* Check if this vmemmap page is already initialised. If any section
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* which overlaps this vmemmap page is initialised then this page is
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* initialised already.
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*/
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static int __meminit vmemmap_populated(unsigned long start, int page_size)
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{
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unsigned long end = start + page_size;
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start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));
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for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
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if (pfn_valid(page_to_pfn((struct page *)start)))
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return 1;
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return 0;
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}
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/*
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* vmemmap virtual address space management does not have a traditonal page
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* table to track which virtual struct pages are backed by physical mapping.
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* The virtual to physical mappings are tracked in a simple linked list
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* format. 'vmemmap_list' maintains the entire vmemmap physical mapping at
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* all times where as the 'next' list maintains the available
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* vmemmap_backing structures which have been deleted from the
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* 'vmemmap_global' list during system runtime (memory hotplug remove
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* operation). The freed 'vmemmap_backing' structures are reused later when
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* new requests come in without allocating fresh memory. This pointer also
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* tracks the allocated 'vmemmap_backing' structures as we allocate one
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* full page memory at a time when we dont have any.
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*/
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struct vmemmap_backing *vmemmap_list;
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static struct vmemmap_backing *next;
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/*
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* The same pointer 'next' tracks individual chunks inside the allocated
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* full page during the boot time and again tracks the freeed nodes during
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* runtime. It is racy but it does not happen as they are separated by the
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* boot process. Will create problem if some how we have memory hotplug
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* operation during boot !!
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*/
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static int num_left;
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static int num_freed;
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static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
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{
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struct vmemmap_backing *vmem_back;
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/* get from freed entries first */
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if (num_freed) {
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num_freed--;
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vmem_back = next;
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next = next->list;
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return vmem_back;
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}
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/* allocate a page when required and hand out chunks */
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if (!num_left) {
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next = vmemmap_alloc_block(PAGE_SIZE, node);
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if (unlikely(!next)) {
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WARN_ON(1);
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return NULL;
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}
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num_left = PAGE_SIZE / sizeof(struct vmemmap_backing);
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}
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num_left--;
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return next++;
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}
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static __meminit void vmemmap_list_populate(unsigned long phys,
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unsigned long start,
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int node)
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{
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struct vmemmap_backing *vmem_back;
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vmem_back = vmemmap_list_alloc(node);
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if (unlikely(!vmem_back)) {
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WARN_ON(1);
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return;
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}
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vmem_back->phys = phys;
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vmem_back->virt_addr = start;
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vmem_back->list = vmemmap_list;
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vmemmap_list = vmem_back;
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}
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int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
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struct vmem_altmap *altmap)
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{
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unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
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/* Align to the page size of the linear mapping. */
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start = _ALIGN_DOWN(start, page_size);
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pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
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for (; start < end; start += page_size) {
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void *p = NULL;
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int rc;
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if (vmemmap_populated(start, page_size))
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continue;
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/*
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* Allocate from the altmap first if we have one. This may
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* fail due to alignment issues when using 16MB hugepages, so
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* fall back to system memory if the altmap allocation fail.
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*/
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if (altmap)
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p = altmap_alloc_block_buf(page_size, altmap);
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if (!p)
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p = vmemmap_alloc_block_buf(page_size, node);
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if (!p)
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return -ENOMEM;
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vmemmap_list_populate(__pa(p), start, node);
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pr_debug(" * %016lx..%016lx allocated at %p\n",
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start, start + page_size, p);
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rc = vmemmap_create_mapping(start, page_size, __pa(p));
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if (rc < 0) {
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pr_warn("%s: Unable to create vmemmap mapping: %d\n",
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__func__, rc);
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return -EFAULT;
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}
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}
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return 0;
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}
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#ifdef CONFIG_MEMORY_HOTPLUG
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static unsigned long vmemmap_list_free(unsigned long start)
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{
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struct vmemmap_backing *vmem_back, *vmem_back_prev;
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vmem_back_prev = vmem_back = vmemmap_list;
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/* look for it with prev pointer recorded */
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for (; vmem_back; vmem_back = vmem_back->list) {
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if (vmem_back->virt_addr == start)
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break;
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vmem_back_prev = vmem_back;
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}
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if (unlikely(!vmem_back)) {
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WARN_ON(1);
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return 0;
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}
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/* remove it from vmemmap_list */
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if (vmem_back == vmemmap_list) /* remove head */
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vmemmap_list = vmem_back->list;
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else
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vmem_back_prev->list = vmem_back->list;
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/* next point to this freed entry */
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vmem_back->list = next;
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next = vmem_back;
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num_freed++;
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return vmem_back->phys;
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}
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void __ref vmemmap_free(unsigned long start, unsigned long end,
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struct vmem_altmap *altmap)
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{
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unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
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unsigned long page_order = get_order(page_size);
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unsigned long alt_start = ~0, alt_end = ~0;
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unsigned long base_pfn;
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start = _ALIGN_DOWN(start, page_size);
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if (altmap) {
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alt_start = altmap->base_pfn;
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alt_end = altmap->base_pfn + altmap->reserve +
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altmap->free + altmap->alloc + altmap->align;
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}
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pr_debug("vmemmap_free %lx...%lx\n", start, end);
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for (; start < end; start += page_size) {
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unsigned long nr_pages, addr;
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struct page *section_base;
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struct page *page;
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/*
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* the section has already be marked as invalid, so
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* vmemmap_populated() true means some other sections still
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* in this page, so skip it.
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*/
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if (vmemmap_populated(start, page_size))
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continue;
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addr = vmemmap_list_free(start);
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if (!addr)
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continue;
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page = pfn_to_page(addr >> PAGE_SHIFT);
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section_base = pfn_to_page(vmemmap_section_start(start));
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nr_pages = 1 << page_order;
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base_pfn = PHYS_PFN(addr);
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if (base_pfn >= alt_start && base_pfn < alt_end) {
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vmem_altmap_free(altmap, nr_pages);
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} else if (PageReserved(page)) {
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/* allocated from bootmem */
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if (page_size < PAGE_SIZE) {
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/*
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* this shouldn't happen, but if it is
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* the case, leave the memory there
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*/
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WARN_ON_ONCE(1);
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} else {
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while (nr_pages--)
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free_reserved_page(page++);
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}
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} else {
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free_pages((unsigned long)(__va(addr)), page_order);
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}
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vmemmap_remove_mapping(start, page_size);
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}
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}
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#endif
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void register_page_bootmem_memmap(unsigned long section_nr,
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struct page *start_page, unsigned long size)
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{
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}
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#endif /* CONFIG_SPARSEMEM_VMEMMAP */
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#ifdef CONFIG_PPC_BOOK3S_64
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static bool disable_radix = !IS_ENABLED(CONFIG_PPC_RADIX_MMU_DEFAULT);
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static int __init parse_disable_radix(char *p)
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{
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bool val;
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if (!p)
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val = true;
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else if (kstrtobool(p, &val))
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return -EINVAL;
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disable_radix = val;
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return 0;
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}
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early_param("disable_radix", parse_disable_radix);
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/*
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* If we're running under a hypervisor, we need to check the contents of
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* /chosen/ibm,architecture-vec-5 to see if the hypervisor is willing to do
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* radix. If not, we clear the radix feature bit so we fall back to hash.
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*/
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static void __init early_check_vec5(void)
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{
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unsigned long root, chosen;
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int size;
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const u8 *vec5;
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u8 mmu_supported;
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root = of_get_flat_dt_root();
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chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
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if (chosen == -FDT_ERR_NOTFOUND) {
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cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
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return;
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}
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vec5 = of_get_flat_dt_prop(chosen, "ibm,architecture-vec-5", &size);
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if (!vec5) {
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cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
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return;
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}
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if (size <= OV5_INDX(OV5_MMU_SUPPORT)) {
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cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
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return;
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}
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/* Check for supported configuration */
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mmu_supported = vec5[OV5_INDX(OV5_MMU_SUPPORT)] &
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OV5_FEAT(OV5_MMU_SUPPORT);
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if (mmu_supported == OV5_FEAT(OV5_MMU_RADIX)) {
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/* Hypervisor only supports radix - check enabled && GTSE */
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if (!early_radix_enabled()) {
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pr_warn("WARNING: Ignoring cmdline option disable_radix\n");
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}
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if (!(vec5[OV5_INDX(OV5_RADIX_GTSE)] &
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OV5_FEAT(OV5_RADIX_GTSE))) {
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pr_warn("WARNING: Hypervisor doesn't support RADIX with GTSE\n");
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}
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/* Do radix anyway - the hypervisor said we had to */
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cur_cpu_spec->mmu_features |= MMU_FTR_TYPE_RADIX;
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} else if (mmu_supported == OV5_FEAT(OV5_MMU_HASH)) {
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/* Hypervisor only supports hash - disable radix */
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cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
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}
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}
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void __init mmu_early_init_devtree(void)
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{
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/* Disable radix mode based on kernel command line. */
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if (disable_radix)
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cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX;
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/*
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* Check /chosen/ibm,architecture-vec-5 if running as a guest.
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* When running bare-metal, we can use radix if we like
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* even though the ibm,architecture-vec-5 property created by
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* skiboot doesn't have the necessary bits set.
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*/
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if (!(mfmsr() & MSR_HV))
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early_check_vec5();
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if (early_radix_enabled())
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radix__early_init_devtree();
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else
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hash__early_init_devtree();
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}
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#endif /* CONFIG_PPC_BOOK3S_64 */
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