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![Aneesh Kumar K.V](/assets/img/avatar_default.png)
Both RMA and hash page table request will be a multiple of 256K. We can use a chunk size of 256K to track the free/used 256K chunk in the bitmap. This should help to reduce the bitmap size. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
240 lines
6.3 KiB
C
240 lines
6.3 KiB
C
/*
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* Contiguous Memory Allocator for ppc KVM hash pagetable based on CMA
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* for DMA mapping framework
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*
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* Copyright IBM Corporation, 2013
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* Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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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 as
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* published by the Free Software Foundation; either version 2 of the
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* License or (at your optional) any later version of the license.
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*
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*/
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#define pr_fmt(fmt) "kvm_cma: " fmt
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#ifdef CONFIG_CMA_DEBUG
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#ifndef DEBUG
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# define DEBUG
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#endif
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#endif
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#include <linux/memblock.h>
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#include <linux/mutex.h>
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#include <linux/sizes.h>
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#include <linux/slab.h>
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#include "book3s_hv_cma.h"
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struct kvm_cma {
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unsigned long base_pfn;
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unsigned long count;
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unsigned long *bitmap;
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};
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static DEFINE_MUTEX(kvm_cma_mutex);
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static struct kvm_cma kvm_cma_area;
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/**
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* kvm_cma_declare_contiguous() - reserve area for contiguous memory handling
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* for kvm hash pagetable
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* @size: Size of the reserved memory.
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* @alignment: Alignment for the contiguous memory area
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*
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* This function reserves memory for kvm cma area. It should be
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* called by arch code when early allocator (memblock or bootmem)
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* is still activate.
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*/
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long __init kvm_cma_declare_contiguous(phys_addr_t size, phys_addr_t alignment)
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{
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long base_pfn;
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phys_addr_t addr;
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struct kvm_cma *cma = &kvm_cma_area;
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pr_debug("%s(size %lx)\n", __func__, (unsigned long)size);
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if (!size)
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return -EINVAL;
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/*
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* Sanitise input arguments.
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* We should be pageblock aligned for CMA.
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*/
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alignment = max(alignment, (phys_addr_t)(PAGE_SIZE << pageblock_order));
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size = ALIGN(size, alignment);
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/*
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* Reserve memory
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* Use __memblock_alloc_base() since
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* memblock_alloc_base() panic()s.
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*/
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addr = __memblock_alloc_base(size, alignment, 0);
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if (!addr) {
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base_pfn = -ENOMEM;
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goto err;
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} else
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base_pfn = PFN_DOWN(addr);
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/*
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* Each reserved area must be initialised later, when more kernel
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* subsystems (like slab allocator) are available.
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*/
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cma->base_pfn = base_pfn;
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cma->count = size >> PAGE_SHIFT;
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pr_info("CMA: reserved %ld MiB\n", (unsigned long)size / SZ_1M);
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return 0;
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err:
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pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
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return base_pfn;
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}
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/**
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* kvm_alloc_cma() - allocate pages from contiguous area
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* @nr_pages: Requested number of pages.
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* @align_pages: Requested alignment in number of pages
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*
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* This function allocates memory buffer for hash pagetable.
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*/
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struct page *kvm_alloc_cma(unsigned long nr_pages, unsigned long align_pages)
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{
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int ret;
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struct page *page = NULL;
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struct kvm_cma *cma = &kvm_cma_area;
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unsigned long chunk_count, nr_chunk;
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unsigned long mask, pfn, pageno, start = 0;
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if (!cma || !cma->count)
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return NULL;
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pr_debug("%s(cma %p, count %lu, align pages %lu)\n", __func__,
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(void *)cma, nr_pages, align_pages);
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if (!nr_pages)
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return NULL;
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/*
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* align mask with chunk size. The bit tracks pages in chunk size
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*/
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VM_BUG_ON(!is_power_of_2(align_pages));
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mask = (align_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT)) - 1;
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BUILD_BUG_ON(PAGE_SHIFT > KVM_CMA_CHUNK_ORDER);
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chunk_count = cma->count >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
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nr_chunk = nr_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
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mutex_lock(&kvm_cma_mutex);
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for (;;) {
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pageno = bitmap_find_next_zero_area(cma->bitmap, chunk_count,
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start, nr_chunk, mask);
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if (pageno >= chunk_count)
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break;
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pfn = cma->base_pfn + (pageno << (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT));
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ret = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_CMA);
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if (ret == 0) {
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bitmap_set(cma->bitmap, pageno, nr_chunk);
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page = pfn_to_page(pfn);
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memset(pfn_to_kaddr(pfn), 0, nr_pages << PAGE_SHIFT);
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break;
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} else if (ret != -EBUSY) {
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break;
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}
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pr_debug("%s(): memory range at %p is busy, retrying\n",
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__func__, pfn_to_page(pfn));
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/* try again with a bit different memory target */
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start = pageno + mask + 1;
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}
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mutex_unlock(&kvm_cma_mutex);
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pr_debug("%s(): returned %p\n", __func__, page);
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return page;
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}
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/**
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* kvm_release_cma() - release allocated pages for hash pagetable
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* @pages: Allocated pages.
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* @nr_pages: Number of allocated pages.
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*
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* This function releases memory allocated by kvm_alloc_cma().
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* It returns false when provided pages do not belong to contiguous area and
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* true otherwise.
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*/
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bool kvm_release_cma(struct page *pages, unsigned long nr_pages)
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{
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unsigned long pfn;
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unsigned long nr_chunk;
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struct kvm_cma *cma = &kvm_cma_area;
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if (!cma || !pages)
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return false;
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pr_debug("%s(page %p count %lu)\n", __func__, (void *)pages, nr_pages);
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pfn = page_to_pfn(pages);
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if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
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return false;
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VM_BUG_ON(pfn + nr_pages > cma->base_pfn + cma->count);
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nr_chunk = nr_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
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mutex_lock(&kvm_cma_mutex);
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bitmap_clear(cma->bitmap,
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(pfn - cma->base_pfn) >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT),
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nr_chunk);
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free_contig_range(pfn, nr_pages);
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mutex_unlock(&kvm_cma_mutex);
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return true;
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}
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static int __init kvm_cma_activate_area(unsigned long base_pfn,
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unsigned long count)
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{
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unsigned long pfn = base_pfn;
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unsigned i = count >> pageblock_order;
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struct zone *zone;
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WARN_ON_ONCE(!pfn_valid(pfn));
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zone = page_zone(pfn_to_page(pfn));
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do {
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unsigned j;
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base_pfn = pfn;
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for (j = pageblock_nr_pages; j; --j, pfn++) {
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WARN_ON_ONCE(!pfn_valid(pfn));
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/*
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* alloc_contig_range requires the pfn range
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* specified to be in the same zone. Make this
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* simple by forcing the entire CMA resv range
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* to be in the same zone.
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*/
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if (page_zone(pfn_to_page(pfn)) != zone)
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return -EINVAL;
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}
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init_cma_reserved_pageblock(pfn_to_page(base_pfn));
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} while (--i);
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return 0;
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}
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static int __init kvm_cma_init_reserved_areas(void)
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{
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int bitmap_size, ret;
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unsigned long chunk_count;
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struct kvm_cma *cma = &kvm_cma_area;
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pr_debug("%s()\n", __func__);
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if (!cma->count)
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return 0;
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chunk_count = cma->count >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
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bitmap_size = BITS_TO_LONGS(chunk_count) * sizeof(long);
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cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
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if (!cma->bitmap)
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return -ENOMEM;
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ret = kvm_cma_activate_area(cma->base_pfn, cma->count);
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if (ret)
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goto error;
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return 0;
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error:
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kfree(cma->bitmap);
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return ret;
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}
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core_initcall(kvm_cma_init_reserved_areas);
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