On Thu, Sep 5, 2024 at 9:18 PM Stefan Hajnoczi <stefa...@redhat.com> wrote:
> On Wed, Sep 04, 2024 at 03:01:06PM +0200, Albert Esteve wrote:
> > On Thu, Jul 11, 2024 at 10:55 AM Stefan Hajnoczi <stefa...@redhat.com>
> > wrote:
> >
> > > On Fri, Jun 28, 2024 at 04:57:10PM +0200, Albert Esteve wrote:
> > > > Implement function handlers for memory read and write
> > > > operations.
> > > >
> > > > Signed-off-by: Albert Esteve <aest...@redhat.com>
> > > > ---
> > > > hw/virtio/vhost-user.c | 34 ++++++++++++++++++++++++++++++----
> > > > 1 file changed, 30 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > > > index 18cacb2d68..79becbc87b 100644
> > > > --- a/hw/virtio/vhost-user.c
> > > > +++ b/hw/virtio/vhost-user.c
> > > > @@ -1884,16 +1884,42 @@ static int
> > > > vhost_user_backend_handle_mem_read(struct vhost_dev *dev,
> > > > VhostUserMemRWMsg *mem_rw)
> > > > {
> > > > - /* TODO */
> > > > - return -EPERM;
> > > > + ram_addr_t offset;
> > > > + int fd;
> > > > + MemoryRegion *mr;
> > > > +
> > > > + mr = vhost_user_get_mr_data(mem_rw->guest_address, &offset,
> &fd);
> > > > +
> > > > + if (!mr) {
> > > > + error_report("Failed to get memory region with address %"
> > > PRIx64,
> > > > + mem_rw->guest_address);
> > > > + return -EFAULT;
> > > > + }
> > > > +
> > > > + memcpy(mem_rw->data, memory_region_get_ram_ptr(mr) + offset,
> > > mem_rw->size);
> > >
> > > Don't try to write this from scratch. Use address_space_read/write().
> It
> > > supports corner cases like crossing MemoryRegions.
> > >
> >
> > I am having issues getting the address space from the vhost_dev struct to
> > feed
> > address_spave_read/write() function with the first parameter. But I found
> > mr->ops.
> > Would something like this perhaps be enough?
> >
> > ```
> > mr->ops->read_with_attrs(mr->opaque, mem_rw->guest_address,
> > &mem_rw->data, mem_rw->size,
> > MEMTXATTRS_UNSPECIFIED);
> > ```
>
> You can use dev->vdev->dma_as to get the AddressSpace for
> address_space_read/write():
>
Oof, I see, thanks!
I still struggle a bit with the structs relationships...
>
> struct vhost_dev {
> VirtIODevice *vdev;
>
> struct VirtIODevice
> {
> ...
> AddressSpace *dma_as;
>
> >
> >
> > >
> > > > +
> > > > + return 0;
> > > > }
> > > >
> > > > static int
> > > > vhost_user_backend_handle_mem_write(struct vhost_dev *dev,
> > > > VhostUserMemRWMsg *mem_rw)
> > > > {
> > > > - /* TODO */
> > > > - return -EPERM;
> > > > + ram_addr_t offset;
> > > > + int fd;
> > > > + MemoryRegion *mr;
> > > > +
> > > > + mr = vhost_user_get_mr_data(mem_rw->guest_address, &offset,
> &fd);
> > > > +
> > > > + if (!mr) {
> > > > + error_report("Failed to get memory region with address %"
> > > PRIx64,
> > > > + mem_rw->guest_address);
> > > > + return -EFAULT;
> > > > + }
> > > > +
> > > > + memcpy(memory_region_get_ram_ptr(mr) + offset, mem_rw->data,
> > > mem_rw->size);
> > > > +
> > > > + return 0;
> > > > }
> > > >
> > > > static void close_backend_channel(struct vhost_user *u)
> > > > --
> > > > 2.45.2
> > > >
> > >
>
