On 07/23/2015 09:36 AM, Marc-André Lureau wrote:
> If the backend is of type VHOST_BACKEND_TYPE_USER, allocate
> shareable memory.
>
> Note: vhost_log_get() can use a global "vhost_log" that can be shared by
> several vhost devices. We may want instead a common shareable log and a
> common non-shareable one.
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> hw/virtio/vhost.c | 42 +++++++++++++++++++++++++++++++++---------
> include/hw/virtio/vhost.h | 3 ++-
> 2 files changed, 35 insertions(+), 10 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 2712c6f..12dd644 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -286,20 +286,34 @@ 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);
> + if (!vhost_log || vhost_log->size != size ||
> + (share && vhost_log->fd == -1)) {
> + vhost_log = vhost_log_alloc(size, share);
> } else {
> ++vhost_log->refcnt;
> }
> @@ -324,21 +338,30 @@ static void vhost_log_put(struct vhost_dev *dev, bool
> sync)
> if (vhost_log == log) {
> vhost_log = NULL;
> }
> +
> + if (log->fd == -1) {
> + g_free(log->log);
> + } else {
> + qemu_memfd_free(log->log, log->size * sizeof(*(log->log)),
> + log->fd);
> + }
> g_free(log);
> }
> }
>
> static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)
> {
> - struct vhost_log *log = vhost_log_get(size);
> + bool share = dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER;
> + struct vhost_log *log = vhost_log_get(size, share);
> uint64_t log_base = (uintptr_t)log->log;
> int r;
>
> - r = dev->vhost_ops->vhost_call(dev, VHOST_SET_LOG_BASE, &log_base);
> - assert(r >= 0);
> vhost_log_put(dev, true);
> dev->log = log;
> dev->log_size = size;
> +
> + r = dev->vhost_ops->vhost_call(dev, VHOST_SET_LOG_BASE, &log_base);
> + assert(r >= 0);
> }
Why this change is needed?
>
> static int vhost_verify_ring_mappings(struct vhost_dev *dev,
> @@ -1136,9 +1159,10 @@ int vhost_dev_start(struct vhost_dev *hdev,
> VirtIODevice *vdev)
>
> if (hdev->log_enabled) {
> uint64_t log_base;
> + bool share = hdev->vhost_ops->backend_type ==
> VHOST_BACKEND_TYPE_USER;
>
> hdev->log_size = vhost_get_log_size(hdev);
> - hdev->log = vhost_log_get(hdev->log_size);
> + hdev->log = vhost_log_get(hdev->log_size, share);
> log_base = (uintptr_t)hdev->log->log;
> r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_LOG_BASE,
> hdev->log_size ? &log_base : NULL);
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 6467c73..ab1dcac 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -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;
