forked from Minki/linux
8e0861fa3c
The current VFIO-on-POWER implementation supports only user mode driven mapping, i.e. QEMU is sending requests to map/unmap pages. However this approach is really slow, so we want to move that to KVM. Since H_PUT_TCE can be extremely performance sensitive (especially with network adapters where each packet needs to be mapped/unmapped) we chose to implement that as a "fast" hypercall directly in "real mode" (processor still in the guest context but MMU off). To be able to do that, we need to provide some facilities to access the struct page count within that real mode environment as things like the sparsemem vmemmap mappings aren't accessible. This adds an API function realmode_pfn_to_page() to get page struct when MMU is off. This adds to MM a new function put_page_unless_one() which drops a page if counter is bigger than 1. It is going to be used when MMU is off (for example, real mode on PPC64) and we want to make sure that page release will not happen in real mode as it may crash the kernel in a horrible way. CONFIG_SPARSEMEM_VMEMMAP and CONFIG_FLATMEM are supported. Cc: linux-mm@kvack.org Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
358 lines
10 KiB
C
358 lines
10 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/bootmem.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 <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 <asm/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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#ifdef CONFIG_PPC_STD_MMU_64
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#if PGTABLE_RANGE > USER_VSID_RANGE
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#warning Limited user VSID range means pagetable space is wasted
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#endif
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#if (TASK_SIZE_USER64 < PGTABLE_RANGE) && (TASK_SIZE_USER64 < USER_VSID_RANGE)
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#warning TASK_SIZE is smaller than it needs to be.
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#endif
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#endif /* CONFIG_PPC_STD_MMU_64 */
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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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static void pgd_ctor(void *addr)
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{
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memset(addr, 0, PGD_TABLE_SIZE);
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}
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static void pmd_ctor(void *addr)
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{
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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memset(addr, 0, PMD_TABLE_SIZE * 2);
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#else
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memset(addr, 0, PMD_TABLE_SIZE);
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#endif
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}
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struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];
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/*
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* Create a kmem_cache() for pagetables. This is not used for PTE
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* pages - they're linked to struct page, come from the normal free
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* pages pool and have a different entry size (see real_pte_t) to
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* everything else. Caches created by this function are used for all
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* the higher level pagetables, and for hugepage pagetables.
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*/
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void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
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{
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char *name;
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unsigned long table_size = sizeof(void *) << shift;
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unsigned long align = table_size;
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/* When batching pgtable pointers for RCU freeing, we store
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* the index size in the low bits. Table alignment must be
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* big enough to fit it.
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*
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* Likewise, hugeapge pagetable pointers contain a (different)
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* shift value in the low bits. All tables must be aligned so
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* as to leave enough 0 bits in the address to contain it. */
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unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
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HUGEPD_SHIFT_MASK + 1);
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struct kmem_cache *new;
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/* It would be nice if this was a BUILD_BUG_ON(), but at the
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* moment, gcc doesn't seem to recognize is_power_of_2 as a
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* constant expression, so so much for that. */
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BUG_ON(!is_power_of_2(minalign));
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BUG_ON((shift < 1) || (shift > MAX_PGTABLE_INDEX_SIZE));
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if (PGT_CACHE(shift))
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return; /* Already have a cache of this size */
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align = max_t(unsigned long, align, minalign);
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name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
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new = kmem_cache_create(name, table_size, align, 0, ctor);
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pgtable_cache[shift - 1] = new;
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pr_debug("Allocated pgtable cache for order %d\n", shift);
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}
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void pgtable_cache_init(void)
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{
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pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
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pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
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if (!PGT_CACHE(PGD_INDEX_SIZE) || !PGT_CACHE(PMD_CACHE_INDEX))
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panic("Couldn't allocate pgtable caches");
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/* In all current configs, when the PUD index exists it's the
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* same size as either the pgd or pmd index. Verify that the
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* initialization above has also created a PUD cache. This
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* will need re-examiniation if we add new possibilities for
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* the pagetable layout. */
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BUG_ON(PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE));
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}
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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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for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
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if (pfn_valid(vmemmap_section_start(start)))
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return 1;
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return 0;
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}
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/* On hash-based CPUs, the vmemmap is bolted in the hash table.
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*
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* On Book3E CPUs, the vmemmap is currently mapped in the top half of
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* the vmalloc space using normal page tables, though the size of
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* pages encoded in the PTEs can be different
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*/
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#ifdef CONFIG_PPC_BOOK3E
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static void __meminit vmemmap_create_mapping(unsigned long start,
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unsigned long page_size,
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unsigned long phys)
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{
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/* Create a PTE encoding without page size */
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unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
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_PAGE_KERNEL_RW;
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/* PTEs only contain page size encodings up to 32M */
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BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);
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/* Encode the size in the PTE */
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flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;
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/* For each PTE for that area, map things. Note that we don't
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* increment phys because all PTEs are of the large size and
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* thus must have the low bits clear
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*/
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for (i = 0; i < page_size; i += PAGE_SIZE)
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BUG_ON(map_kernel_page(start + i, phys, flags));
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}
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#else /* CONFIG_PPC_BOOK3E */
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static void __meminit vmemmap_create_mapping(unsigned long start,
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unsigned long page_size,
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unsigned long phys)
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{
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int mapped = htab_bolt_mapping(start, start + page_size, phys,
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pgprot_val(PAGE_KERNEL),
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mmu_vmemmap_psize,
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mmu_kernel_ssize);
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BUG_ON(mapped < 0);
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}
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#endif /* CONFIG_PPC_BOOK3E */
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struct vmemmap_backing *vmemmap_list;
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static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
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{
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static struct vmemmap_backing *next;
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static int num_left;
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/* allocate a page when required and hand out chunks */
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if (!next || !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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{
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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;
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if (vmemmap_populated(start, page_size))
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continue;
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p = vmemmap_alloc_block(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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vmemmap_create_mapping(start, page_size, __pa(p));
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}
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return 0;
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}
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void vmemmap_free(unsigned long start, unsigned long end)
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{
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}
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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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/*
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* We do not have access to the sparsemem vmemmap, so we fallback to
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* walking the list of sparsemem blocks which we already maintain for
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* the sake of crashdump. In the long run, we might want to maintain
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* a tree if performance of that linear walk becomes a problem.
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*
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* realmode_pfn_to_page functions can fail due to:
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* 1) As real sparsemem blocks do not lay in RAM continously (they
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* are in virtual address space which is not available in the real mode),
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* the requested page struct can be split between blocks so get_page/put_page
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* may fail.
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* 2) When huge pages are used, the get_page/put_page API will fail
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* in real mode as the linked addresses in the page struct are virtual
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* too.
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*/
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struct page *realmode_pfn_to_page(unsigned long pfn)
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{
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struct vmemmap_backing *vmem_back;
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struct page *page;
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unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
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unsigned long pg_va = (unsigned long) pfn_to_page(pfn);
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for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
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if (pg_va < vmem_back->virt_addr)
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continue;
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/* Check that page struct is not split between real pages */
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if ((pg_va + sizeof(struct page)) >
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(vmem_back->virt_addr + page_size))
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return NULL;
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page = (struct page *) (vmem_back->phys + pg_va -
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vmem_back->virt_addr);
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return page;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
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#elif defined(CONFIG_FLATMEM)
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struct page *realmode_pfn_to_page(unsigned long pfn)
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{
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struct page *page = pfn_to_page(pfn);
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return page;
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}
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EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
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#endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */
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