Re: [Qemu-devel] [RFC 16/29] vhost+postcopy: Stash RAMBlock and offset

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Xu (peterx@redhat.com) wrote:
> On Wed, Jun 28, 2017 at 08:00:34PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Stash the RAMBlock and offset for later use looking up
> > addresses.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  hw/virtio/trace-events |  1 +
> >  hw/virtio/vhost-user.c | 11 +++++++++++
> >  2 files changed, 12 insertions(+)
> > 
> > diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> > index f7be340a45..1fd194363a 100644
> > --- a/hw/virtio/trace-events
> > +++ b/hw/virtio/trace-events
> > @@ -3,6 +3,7 @@
> >  # hw/virtio/vhost-user.c
> >  vhost_user_postcopy_listen(void) ""
> >  vhost_user_set_mem_table_postcopy(uint64_t client_addr, uint64_t qhva, int reply_i, int region_i) "client:%"PRIx64" for hva: %"PRIx64" reply %d region %d"
> > +vhost_user_set_mem_table_withfd(int index, const char *name, uint64_t memory_size, uint64_t guest_phys_addr, uint64_t userspace_addr, uint64_t offset) "%d:%s: size:%"PRIx64" GPA:%"PRIx64" QVA/userspace:%"PRIx64" RB offset:%"PRIx64
> >  
> >  # hw/virtio/virtio.c
> >  virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned out_num) "elem %p size %zd in_num %u out_num %u"
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index 6be3e7ff2d..3185af7a45 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -133,6 +133,11 @@ struct vhost_user {
> >      NotifierWithReturn postcopy_notifier;
> >      struct PostCopyFD  postcopy_fd;
> >      uint64_t           postcopy_client_bases[VHOST_MEMORY_MAX_NREGIONS];
> > +    RAMBlock          *region_rb[VHOST_MEMORY_MAX_NREGIONS];
> > +    /* The offset from the start of the RAMBlock to the start of the
> > +     * vhost region.
> > +     */
> > +    ram_addr_t         region_rb_offset[VHOST_MEMORY_MAX_NREGIONS];
> 
> Here the array size is VHOST_MEMORY_MAX_NREGIONS, while...
> 
> >  };
> >  
> >  static bool ioeventfd_enabled(void)
> > @@ -324,8 +329,14 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
> >          assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
> >          mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
> >                                       &offset);
> > +        u->region_rb_offset[i] = offset;
> > +        u->region_rb[i] = mr->ram_block;
> 
> ... can i>=VHOST_MEMORY_MAX_NREGIONS here? Or do we only need to note
> this down if fd > 0 below?  Thanks,

I don't *think* so - I mean:
    for (i = 0; i < dev->mem->nregions; ++i) {

so if that's the maximum number of regions and that's the number of
regions we should be safe???

Dave

> >          fd = memory_region_get_fd(mr);
> >          if (fd > 0) {
> > +            trace_vhost_user_set_mem_table_withfd(fd_num, mr->name,
> > +                                                  reg->memory_size,
> > +                                                  reg->guest_phys_addr,
> > +                                                  reg->userspace_addr, offset);
> >              msg.payload.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
> >              msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
> >              msg.payload.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
> > -- 
> > 2.13.0
> > 
> 
> -- 
> Peter Xu
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK