1 files changed, 227 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_cma.c b/arch/powerpc/kvm/book3s_hv_cma.c
new file mode 100644
index 000000000000..e04b269b9c5b
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv_cma.c
@@ -0,0 +1,227 @@
+/*
+ * Contiguous Memory Allocator for ppc KVM hash pagetable  based on CMA
+ * for DMA mapping framework
+ *
+ * Copyright IBM Corporation, 2013
+ * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License or (at your optional) any later version of the license.
+ *
+ */
+#define pr_fmt(fmt) "kvm_cma: " fmt
+
+#ifdef CONFIG_CMA_DEBUG
+#ifndef DEBUG
+#  define DEBUG
+#endif
+#endif
+
+#include <linux/memblock.h>
+#include <linux/mutex.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+
+struct kvm_cma {
+	unsigned long	base_pfn;
+	unsigned long	count;
+	unsigned long	*bitmap;
+};
+
+static DEFINE_MUTEX(kvm_cma_mutex);
+static struct kvm_cma kvm_cma_area;
+
+/**
+ * kvm_cma_declare_contiguous() - reserve area for contiguous memory handling
+ *			          for kvm hash pagetable
+ * @size:  Size of the reserved memory.
+ * @alignment:  Alignment for the contiguous memory area
+ *
+ * This function reserves memory for kvm cma area. It should be
+ * called by arch code when early allocator (memblock or bootmem)
+ * is still activate.
+ */
+long __init kvm_cma_declare_contiguous(phys_addr_t size, phys_addr_t alignment)
+{
+	long base_pfn;
+	phys_addr_t addr;
+	struct kvm_cma *cma = &kvm_cma_area;
+
+	pr_debug("%s(size %lx)\n", __func__, (unsigned long)size);
+
+	if (!size)
+		return -EINVAL;
+	/*
+	 * Sanitise input arguments.
+	 * We should be pageblock aligned for CMA.
+	 */
+	alignment = max(alignment, (phys_addr_t)(PAGE_SIZE << pageblock_order));
+	size = ALIGN(size, alignment);
+	/*
+	 * Reserve memory
+	 * Use __memblock_alloc_base() since
+	 * memblock_alloc_base() panic()s.
+	 */
+	addr = __memblock_alloc_base(size, alignment, 0);
+	if (!addr) {
+		base_pfn = -ENOMEM;
+		goto err;
+	} else
+		base_pfn = PFN_DOWN(addr);
+
+	/*
+	 * Each reserved area must be initialised later, when more kernel
+	 * subsystems (like slab allocator) are available.
+	 */
+	cma->base_pfn = base_pfn;
+	cma->count    = size >> PAGE_SHIFT;
+	pr_info("CMA: reserved %ld MiB\n", (unsigned long)size / SZ_1M);
+	return 0;
+err:
+	pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
+	return base_pfn;
+}
+
+/**
+ * kvm_alloc_cma() - allocate pages from contiguous area
+ * @nr_pages: Requested number of pages.
+ * @align_pages: Requested alignment in number of pages
+ *
+ * This function allocates memory buffer for hash pagetable.
+ */
+struct page *kvm_alloc_cma(unsigned long nr_pages, unsigned long align_pages)
+{
+	int ret;
+	struct page *page = NULL;
+	struct kvm_cma *cma = &kvm_cma_area;
+	unsigned long mask, pfn, pageno, start = 0;
+
+
+	if (!cma || !cma->count)
+		return NULL;
+
+	pr_debug("%s(cma %p, count %lu, align pages %lu)\n", __func__,
+		 (void *)cma, nr_pages, align_pages);
+
+	if (!nr_pages)
+		return NULL;
+
+	VM_BUG_ON(!is_power_of_2(align_pages));
+	mask = align_pages - 1;
+
+	mutex_lock(&kvm_cma_mutex);
+	for (;;) {
+		pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
+						    start, nr_pages, mask);
+		if (pageno >= cma->count)
+			break;
+
+		pfn = cma->base_pfn + pageno;
+		ret = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_CMA);
+		if (ret == 0) {
+			bitmap_set(cma->bitmap, pageno, nr_pages);
+			page = pfn_to_page(pfn);
+			memset(pfn_to_kaddr(pfn), 0, nr_pages << PAGE_SHIFT);
+			break;
+		} else if (ret != -EBUSY) {
+			break;
+		}
+		pr_debug("%s(): memory range at %p is busy, retrying\n",
+			 __func__, pfn_to_page(pfn));
+		/* try again with a bit different memory target */
+		start = pageno + mask + 1;
+	}
+	mutex_unlock(&kvm_cma_mutex);
+	pr_debug("%s(): returned %p\n", __func__, page);
+	return page;
+}
+
+/**
+ * kvm_release_cma() - release allocated pages for hash pagetable
+ * @pages: Allocated pages.
+ * @nr_pages: Number of allocated pages.
+ *
+ * This function releases memory allocated by kvm_alloc_cma().
+ * It returns false when provided pages do not belong to contiguous area and
+ * true otherwise.
+ */
+bool kvm_release_cma(struct page *pages, unsigned long nr_pages)
+{
+	unsigned long pfn;
+	struct kvm_cma *cma = &kvm_cma_area;
+
+
+	if (!cma || !pages)
+		return false;
+
+	pr_debug("%s(page %p count %lu)\n", __func__, (void *)pages, nr_pages);
+
+	pfn = page_to_pfn(pages);
+
+	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
+		return false;
+
+	VM_BUG_ON(pfn + nr_pages > cma->base_pfn + cma->count);
+
+	mutex_lock(&kvm_cma_mutex);
+	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, nr_pages);
+	free_contig_range(pfn, nr_pages);
+	mutex_unlock(&kvm_cma_mutex);
+
+	return true;
+}
+
+static int __init kvm_cma_activate_area(unsigned long base_pfn,
+					unsigned long count)
+{
+	unsigned long pfn = base_pfn;
+	unsigned i = count >> pageblock_order;
+	struct zone *zone;
+
+	WARN_ON_ONCE(!pfn_valid(pfn));
+	zone = page_zone(pfn_to_page(pfn));
+	do {
+		unsigned j;
+		base_pfn = pfn;
+		for (j = pageblock_nr_pages; j; --j, pfn++) {
+			WARN_ON_ONCE(!pfn_valid(pfn));
+			/*
+			 * alloc_contig_range requires the pfn range
+			 * specified to be in the same zone. Make this
+			 * simple by forcing the entire CMA resv range
+			 * to be in the same zone.
+			 */
+			if (page_zone(pfn_to_page(pfn)) != zone)
+				return -EINVAL;
+		}
+		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
+	} while (--i);
+	return 0;
+}
+
+static int __init kvm_cma_init_reserved_areas(void)
+{
+	int bitmap_size, ret;
+	struct kvm_cma *cma = &kvm_cma_area;
+
+	pr_debug("%s()\n", __func__);
+	if (!cma->count)
+		return 0;
+
+	bitmap_size = BITS_TO_LONGS(cma->count) * sizeof(long);
+	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!cma->bitmap)
+		return -ENOMEM;
+
+	ret = kvm_cma_activate_area(cma->base_pfn, cma->count);
+	if (ret)
+		goto error;
+	return 0;
+
+error:
+	kfree(cma->bitmap);
+	return ret;
+}
+core_initcall(kvm_cma_init_reserved_areas);