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@@ -0,0 +1,227 @@
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+/*
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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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+
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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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+
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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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+
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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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+
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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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+/**
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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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+
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+ pr_debug("%s(size %lx)\n", __func__, (unsigned long)size);
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+
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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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+ /*
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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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+/**
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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 mask, pfn, pageno, start = 0;
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+
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+
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+ if (!cma || !cma->count)
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+ return NULL;
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+
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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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+
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+ if (!nr_pages)
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+ return NULL;
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+
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+ VM_BUG_ON(!is_power_of_2(align_pages));
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+ mask = align_pages - 1;
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+
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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, cma->count,
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+ start, nr_pages, mask);
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+ if (pageno >= cma->count)
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+ break;
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+
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+ pfn = cma->base_pfn + pageno;
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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_pages);
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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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+/**
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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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+ struct kvm_cma *cma = &kvm_cma_area;
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+
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+
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+ if (!cma || !pages)
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+ return false;
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+
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+ pr_debug("%s(page %p count %lu)\n", __func__, (void *)pages, nr_pages);
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+
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+ pfn = page_to_pfn(pages);
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+
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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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+
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+ VM_BUG_ON(pfn + nr_pages > cma->base_pfn + cma->count);
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+
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+ mutex_lock(&kvm_cma_mutex);
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+ bitmap_clear(cma->bitmap, pfn - cma->base_pfn, nr_pages);
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+ free_contig_range(pfn, nr_pages);
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+ mutex_unlock(&kvm_cma_mutex);
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+
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+ return true;
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+}
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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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+
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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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+
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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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+ struct kvm_cma *cma = &kvm_cma_area;
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+
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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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+
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+ bitmap_size = BITS_TO_LONGS(cma->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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+
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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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+
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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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Aneesh Kumar K.V