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powerpc/kvm: Use 256K chunk to track both RMA and hash page table allocation.

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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>
This commit is contained in:
Aneesh Kumar K.V 2013-07-02 11:15:18 +05:30 committed by Alexander Graf
parent 6c45b81098
commit 990978e993
3 changed files with 32 additions and 11 deletions
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3
arch/powerpc/kvm/book3s_64_mmu_hv.c
View file

@ -37,6 +37,8 @@
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>
#include "book3s_hv_cma.h"
/* POWER7 has 10-bit LPIDs, PPC970 has 6-bit LPIDs */
#define MAX_LPID_970 63
@ -71,6 +73,7 @@ long kvmppc_alloc_hpt(struct kvm *kvm, u32 *htab_orderp)
/* Next try to allocate from the preallocated pool */
if (!hpt) {
VM_BUG_ON(order < KVM_CMA_CHUNK_ORDER);
page = kvm_alloc_hpt(1 << (order - PAGE_SHIFT));
if (page) {
hpt = (unsigned long)pfn_to_kaddr(page_to_pfn(page));

35
arch/powerpc/kvm/book3s_hv_cma.c
View file

@ -24,6 +24,8 @@
#include <linux/sizes.h>
#include <linux/slab.h>
#include "book3s_hv_cma.h"
struct kvm_cma {
unsigned long base_pfn;
unsigned long count;
@ -96,6 +98,7 @@ 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 chunk_count, nr_chunk;
unsigned long mask, pfn, pageno, start = 0;
@ -107,21 +110,27 @@ struct page *kvm_alloc_cma(unsigned long nr_pages, unsigned long align_pages)
if (!nr_pages)
return NULL;
/*
* align mask with chunk size. The bit tracks pages in chunk size
*/
VM_BUG_ON(!is_power_of_2(align_pages));
mask = align_pages - 1;
mask = (align_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT)) - 1;
BUILD_BUG_ON(PAGE_SHIFT > KVM_CMA_CHUNK_ORDER);
chunk_count = cma->count >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
nr_chunk = nr_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
mutex_lock(&kvm_cma_mutex);
for (;;) {
pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
start, nr_pages, mask);
if (pageno >= cma->count)
pageno = bitmap_find_next_zero_area(cma->bitmap, chunk_count,
start, nr_chunk, mask);
if (pageno >= chunk_count)
break;
pfn = cma->base_pfn + pageno;
pfn = cma->base_pfn + (pageno << (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT));
ret = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_CMA);
if (ret == 0) {
bitmap_set(cma->bitmap, pageno, nr_pages);
bitmap_set(cma->bitmap, pageno, nr_chunk);
page = pfn_to_page(pfn);
memset(pfn_to_kaddr(pfn), 0, nr_pages << PAGE_SHIFT);
break;
@ -150,9 +159,9 @@ struct page *kvm_alloc_cma(unsigned long nr_pages, unsigned long align_pages)
bool kvm_release_cma(struct page *pages, unsigned long nr_pages)
{
unsigned long pfn;
unsigned long nr_chunk;
struct kvm_cma *cma = &kvm_cma_area;
if (!cma || !pages)
return false;
@ -164,9 +173,12 @@ bool kvm_release_cma(struct page *pages, unsigned long nr_pages)
return false;
VM_BUG_ON(pfn + nr_pages > cma->base_pfn + cma->count);
nr_chunk = nr_pages >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
mutex_lock(&kvm_cma_mutex);
bitmap_clear(cma->bitmap, pfn - cma->base_pfn, nr_pages);
bitmap_clear(cma->bitmap,
(pfn - cma->base_pfn) >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT),
nr_chunk);
free_contig_range(pfn, nr_pages);
mutex_unlock(&kvm_cma_mutex);
@ -204,13 +216,14 @@ static int __init kvm_cma_activate_area(unsigned long base_pfn,
static int __init kvm_cma_init_reserved_areas(void)
{
int bitmap_size, ret;
unsigned long chunk_count;
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);
chunk_count = cma->count >> (KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
bitmap_size = BITS_TO_LONGS(chunk_count) * sizeof(long);
cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
if (!cma->bitmap)
return -ENOMEM;

5
arch/powerpc/kvm/book3s_hv_cma.h
View file

@ -14,6 +14,11 @@
#ifndef __POWERPC_KVM_CMA_ALLOC_H__
#define __POWERPC_KVM_CMA_ALLOC_H__
/*
* Both RMA and Hash page allocation will be multiple of 256K.
*/
#define KVM_CMA_CHUNK_ORDER 18
extern struct page *kvm_alloc_cma(unsigned long nr_pages,
unsigned long align_pages);
extern bool kvm_release_cma(struct page *pages, unsigned long nr_pages);