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vhost: alloc shareable log 

If the backend is requires it, allocate shareable memory.

vhost_log_get() now uses 2 globals "vhost_log" and "vhost_log_shm", that
way there is a common non-shareable log and a common shareable one.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
This commit is contained in:
Marc-André Lureau 2015-10-09 17:17:25 +02:00 committed by Michael S. Tsirkin
parent 1be0ac2109
commit 15324404f6
2 changed files with 49 additions and 11 deletions
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57
hw/virtio/vhost.c
View File

@ -18,6 +18,7 @@
#include "qemu/atomic.h"
#include "qemu/range.h"
#include "qemu/error-report.h"
#include "qemu/memfd.h"
#include <linux/vhost.h>
#include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h"
@ -25,6 +26,7 @@
#include "migration/migration.h"
static struct vhost_log *vhost_log;
static struct vhost_log *vhost_log_shm;
static unsigned int used_memslots;
static QLIST_HEAD(, vhost_dev) vhost_devices =
@ -302,25 +304,46 @@ static uint64_t vhost_get_log_size(struct vhost_dev *dev)
}
return log_size;
}
static struct vhost_log *vhost_log_alloc(uint64_t size)
static struct vhost_log *vhost_log_alloc(uint64_t size, bool share)
{
struct vhost_log *log = g_malloc0(sizeof *log + size * sizeof(*(log->log)));
struct vhost_log *log;
uint64_t logsize = size * sizeof(*(log->log));
int fd = -1;
log = g_new0(struct vhost_log, 1);
if (share) {
log->log = qemu_memfd_alloc("vhost-log", logsize,
F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL,
&fd);
memset(log->log, 0, logsize);
} else {
log->log = g_malloc0(logsize);
}
log->size = size;
log->refcnt = 1;
log->fd = fd;
return log;
}
static struct vhost_log *vhost_log_get(uint64_t size)
static struct vhost_log *vhost_log_get(uint64_t size, bool share)
{
if (!vhost_log || vhost_log->size != size) {
vhost_log = vhost_log_alloc(size);
struct vhost_log *log = share ? vhost_log_shm : vhost_log;
if (!log || log->size != size) {
log = vhost_log_alloc(size, share);
if (share) {
vhost_log_shm = log;
} else {
vhost_log = log;
}
} else {
++vhost_log->refcnt;
++log->refcnt;
}
return vhost_log;
return log;
}
static void vhost_log_put(struct vhost_dev *dev, bool sync)
@ -337,16 +360,29 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync)
if (dev->log_size && sync) {
vhost_log_sync_range(dev, 0, dev->log_size * VHOST_LOG_CHUNK - 1);
}
if (vhost_log == log) {
g_free(log->log);
vhost_log = NULL;
} else if (vhost_log_shm == log) {
qemu_memfd_free(log->log, log->size * sizeof(*(log->log)),
log->fd);
vhost_log_shm = NULL;
}
g_free(log);
}
}
static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)
static bool vhost_dev_log_is_shared(struct vhost_dev *dev)
{
struct vhost_log *log = vhost_log_get(size);
return dev->vhost_ops->vhost_requires_shm_log &&
dev->vhost_ops->vhost_requires_shm_log(dev);
}
static inline void vhost_dev_log_resize(struct vhost_dev *dev, uint64_t size)
{
struct vhost_log *log = vhost_log_get(size, vhost_dev_log_is_shared(dev));
uint64_t log_base = (uintptr_t)log->log;
int r;
@ -1165,7 +1201,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
uint64_t log_base;
hdev->log_size = vhost_get_log_size(hdev);
hdev->log = vhost_log_get(hdev->log_size);
hdev->log = vhost_log_get(hdev->log_size,
vhost_dev_log_is_shared(hdev));
log_base = (uintptr_t)hdev->log->log;
r = hdev->vhost_ops->vhost_set_log_base(hdev,
hdev->log_size ? log_base : 0);

3
include/hw/virtio/vhost.h
View File

@ -31,7 +31,8 @@ typedef unsigned long vhost_log_chunk_t;
struct vhost_log {
unsigned long long size;
int refcnt;
vhost_log_chunk_t log[0];
int fd;
vhost_log_chunk_t *log;
};
struct vhost_memory;