On 3.3.2021 14.45, Yongji Xie wrote:

On Wed, Mar 3, 2021 at 6:52 PM Mika Penttilä [off-list ref] wrote:

quoted

On 23.2.2021 13.50, Xie Yongji wrote:

quoted

This patch introduces an attribute for vDPA device to indicate
whether virtual address can be used. If vDPA device driver set
it, vhost-vdpa bus driver will not pin user page and transfer
userspace virtual address instead of physical address during
DMA mapping. And corresponding vma->vm_file and offset will be
also passed as an opaque pointer.

In the virtual addressing case, who is then responsible for the pinning
or even mapping physical pages to the vaddr?

Actually there's no need to pin the physical pages any more in this
case. The vDPA device should be able to access the user space memory
with virtual address if this attribute is set to true. For example, in
VDUSE case, we will make use of the vma->vm_file to support sharing
the memory between VM and VDUSE daemon.

Thanks,
Yongji

Ah ok you have a shared file pointer + offset.

thanks,
Mika