qemu/xen-mapcache.c
Julien Grall 852a7cec90 xen-mapcache: don't unmap locked entry during mapcache invalidation
When an IOREQ_TYPE_INVALIDATE is sent to QEMU, it invalidates all entry
of the map cache even if it's locked.

QEMU is not able to know that entry was invalidated, so when an IO
access is requested a segfault occured.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
2012-04-13 17:35:06 +00:00

411 lines
12 KiB
C

/*
* Copyright (C) 2011 Citrix Ltd.
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "config.h"
#include <sys/resource.h>
#include "hw/xen_backend.h"
#include "blockdev.h"
#include "bitmap.h"
#include <xen/hvm/params.h>
#include <sys/mman.h>
#include "xen-mapcache.h"
#include "trace.h"
//#define MAPCACHE_DEBUG
#ifdef MAPCACHE_DEBUG
# define DPRINTF(fmt, ...) do { \
fprintf(stderr, "xen_mapcache: " fmt, ## __VA_ARGS__); \
} while (0)
#else
# define DPRINTF(fmt, ...) do { } while (0)
#endif
#if defined(__i386__)
# define MCACHE_BUCKET_SHIFT 16
# define MCACHE_MAX_SIZE (1UL<<31) /* 2GB Cap */
#elif defined(__x86_64__)
# define MCACHE_BUCKET_SHIFT 20
# define MCACHE_MAX_SIZE (1UL<<35) /* 32GB Cap */
#endif
#define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
/* This is the size of the virtual address space reserve to QEMU that will not
* be use by MapCache.
* From empirical tests I observed that qemu use 75MB more than the
* max_mcache_size.
*/
#define NON_MCACHE_MEMORY_SIZE (80 * 1024 * 1024)
#define mapcache_lock() ((void)0)
#define mapcache_unlock() ((void)0)
typedef struct MapCacheEntry {
target_phys_addr_t paddr_index;
uint8_t *vaddr_base;
unsigned long *valid_mapping;
uint8_t lock;
target_phys_addr_t size;
struct MapCacheEntry *next;
} MapCacheEntry;
typedef struct MapCacheRev {
uint8_t *vaddr_req;
target_phys_addr_t paddr_index;
target_phys_addr_t size;
QTAILQ_ENTRY(MapCacheRev) next;
} MapCacheRev;
typedef struct MapCache {
MapCacheEntry *entry;
unsigned long nr_buckets;
QTAILQ_HEAD(map_cache_head, MapCacheRev) locked_entries;
/* For most cases (>99.9%), the page address is the same. */
target_phys_addr_t last_address_index;
uint8_t *last_address_vaddr;
unsigned long max_mcache_size;
unsigned int mcache_bucket_shift;
phys_offset_to_gaddr_t phys_offset_to_gaddr;
void *opaque;
} MapCache;
static MapCache *mapcache;
static inline int test_bits(int nr, int size, const unsigned long *addr)
{
unsigned long res = find_next_zero_bit(addr, size + nr, nr);
if (res >= nr + size)
return 1;
else
return 0;
}
void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
{
unsigned long size;
struct rlimit rlimit_as;
mapcache = g_malloc0(sizeof (MapCache));
mapcache->phys_offset_to_gaddr = f;
mapcache->opaque = opaque;
QTAILQ_INIT(&mapcache->locked_entries);
mapcache->last_address_index = -1;
if (geteuid() == 0) {
rlimit_as.rlim_cur = RLIM_INFINITY;
rlimit_as.rlim_max = RLIM_INFINITY;
mapcache->max_mcache_size = MCACHE_MAX_SIZE;
} else {
getrlimit(RLIMIT_AS, &rlimit_as);
rlimit_as.rlim_cur = rlimit_as.rlim_max;
if (rlimit_as.rlim_max != RLIM_INFINITY) {
fprintf(stderr, "Warning: QEMU's maximum size of virtual"
" memory is not infinity.\n");
}
if (rlimit_as.rlim_max < MCACHE_MAX_SIZE + NON_MCACHE_MEMORY_SIZE) {
mapcache->max_mcache_size = rlimit_as.rlim_max -
NON_MCACHE_MEMORY_SIZE;
} else {
mapcache->max_mcache_size = MCACHE_MAX_SIZE;
}
}
setrlimit(RLIMIT_AS, &rlimit_as);
mapcache->nr_buckets =
(((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
(1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
(MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
size = mapcache->nr_buckets * sizeof (MapCacheEntry);
size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
mapcache->nr_buckets, size);
mapcache->entry = g_malloc0(size);
}
static void xen_remap_bucket(MapCacheEntry *entry,
target_phys_addr_t size,
target_phys_addr_t address_index)
{
uint8_t *vaddr_base;
xen_pfn_t *pfns;
int *err;
unsigned int i;
target_phys_addr_t nb_pfn = size >> XC_PAGE_SHIFT;
trace_xen_remap_bucket(address_index);
pfns = g_malloc0(nb_pfn * sizeof (xen_pfn_t));
err = g_malloc0(nb_pfn * sizeof (int));
if (entry->vaddr_base != NULL) {
if (munmap(entry->vaddr_base, entry->size) != 0) {
perror("unmap fails");
exit(-1);
}
}
if (entry->valid_mapping != NULL) {
g_free(entry->valid_mapping);
entry->valid_mapping = NULL;
}
for (i = 0; i < nb_pfn; i++) {
pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
}
vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
pfns, err, nb_pfn);
if (vaddr_base == NULL) {
perror("xc_map_foreign_bulk");
exit(-1);
}
entry->vaddr_base = vaddr_base;
entry->paddr_index = address_index;
entry->size = size;
entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned long) *
BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
bitmap_zero(entry->valid_mapping, nb_pfn);
for (i = 0; i < nb_pfn; i++) {
if (!err[i]) {
bitmap_set(entry->valid_mapping, i, 1);
}
}
g_free(pfns);
g_free(err);
}
uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
uint8_t lock)
{
MapCacheEntry *entry, *pentry = NULL;
target_phys_addr_t address_index;
target_phys_addr_t address_offset;
target_phys_addr_t __size = size;
bool translated = false;
tryagain:
address_index = phys_addr >> MCACHE_BUCKET_SHIFT;
address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
trace_xen_map_cache(phys_addr);
if (address_index == mapcache->last_address_index && !lock && !__size) {
trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
return mapcache->last_address_vaddr + address_offset;
}
/* size is always a multiple of MCACHE_BUCKET_SIZE */
if (size) {
__size = size + address_offset;
if (__size % MCACHE_BUCKET_SIZE) {
__size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);
}
} else {
__size = MCACHE_BUCKET_SIZE;
}
entry = &mapcache->entry[address_index % mapcache->nr_buckets];
while (entry && entry->lock && entry->vaddr_base &&
(entry->paddr_index != address_index || entry->size != __size ||
!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
entry->valid_mapping))) {
pentry = entry;
entry = entry->next;
}
if (!entry) {
entry = g_malloc0(sizeof (MapCacheEntry));
pentry->next = entry;
xen_remap_bucket(entry, __size, address_index);
} else if (!entry->lock) {
if (!entry->vaddr_base || entry->paddr_index != address_index ||
entry->size != __size ||
!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
entry->valid_mapping)) {
xen_remap_bucket(entry, __size, address_index);
}
}
if(!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
entry->valid_mapping)) {
mapcache->last_address_index = -1;
if (!translated && mapcache->phys_offset_to_gaddr) {
phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size, mapcache->opaque);
translated = true;
goto tryagain;
}
trace_xen_map_cache_return(NULL);
return NULL;
}
mapcache->last_address_index = address_index;
mapcache->last_address_vaddr = entry->vaddr_base;
if (lock) {
MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev));
entry->lock++;
reventry->vaddr_req = mapcache->last_address_vaddr + address_offset;
reventry->paddr_index = mapcache->last_address_index;
reventry->size = entry->size;
QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
}
trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
return mapcache->last_address_vaddr + address_offset;
}
ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
{
MapCacheEntry *entry = NULL;
MapCacheRev *reventry;
target_phys_addr_t paddr_index;
target_phys_addr_t size;
int found = 0;
QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
if (reventry->vaddr_req == ptr) {
paddr_index = reventry->paddr_index;
size = reventry->size;
found = 1;
break;
}
}
if (!found) {
fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
DPRINTF(" "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index,
reventry->vaddr_req);
}
abort();
return 0;
}
entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
entry = entry->next;
}
if (!entry) {
DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
return 0;
}
return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
((unsigned long) ptr - (unsigned long) entry->vaddr_base);
}
void xen_invalidate_map_cache_entry(uint8_t *buffer)
{
MapCacheEntry *entry = NULL, *pentry = NULL;
MapCacheRev *reventry;
target_phys_addr_t paddr_index;
target_phys_addr_t size;
int found = 0;
if (mapcache->last_address_vaddr == buffer) {
mapcache->last_address_index = -1;
}
QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
if (reventry->vaddr_req == buffer) {
paddr_index = reventry->paddr_index;
size = reventry->size;
found = 1;
break;
}
}
if (!found) {
DPRINTF("%s, could not find %p\n", __func__, buffer);
QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
DPRINTF(" "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
}
return;
}
QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
g_free(reventry);
entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
pentry = entry;
entry = entry->next;
}
if (!entry) {
DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
return;
}
entry->lock--;
if (entry->lock > 0 || pentry == NULL) {
return;
}
pentry->next = entry->next;
if (munmap(entry->vaddr_base, entry->size) != 0) {
perror("unmap fails");
exit(-1);
}
g_free(entry->valid_mapping);
g_free(entry);
}
void xen_invalidate_map_cache(void)
{
unsigned long i;
MapCacheRev *reventry;
/* Flush pending AIO before destroying the mapcache */
bdrv_drain_all();
QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
DPRINTF("There should be no locked mappings at this time, "
"but "TARGET_FMT_plx" -> %p is present\n",
reventry->paddr_index, reventry->vaddr_req);
}
mapcache_lock();
for (i = 0; i < mapcache->nr_buckets; i++) {
MapCacheEntry *entry = &mapcache->entry[i];
if (entry->vaddr_base == NULL) {
continue;
}
if (entry->lock > 0) {
continue;
}
if (munmap(entry->vaddr_base, entry->size) != 0) {
perror("unmap fails");
exit(-1);
}
entry->paddr_index = 0;
entry->vaddr_base = NULL;
entry->size = 0;
g_free(entry->valid_mapping);
entry->valid_mapping = NULL;
}
mapcache->last_address_index = -1;
mapcache->last_address_vaddr = NULL;
mapcache_unlock();
}