On Tue, Jul 28, 2015 at 01:28:05PM +0800, Jason Wang wrote:
>
>
> 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?
I know why it's needed :) But this needs to be stated in the commit log.
Also, it only makes sense if remote supports getting the logfd.
> >
> > 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;
