On Mon, Mar 07, 2016 at 02:07:15PM +0800, Jike Song wrote:
> Hi Neo,
>
> On Fri, Mar 4, 2016 at 3:00 PM, Neo Jia <cjia@xxxxxxxxxx> wrote:
> > On Wed, Mar 02, 2016 at 04:38:34PM +0800, Jike Song wrote:
> >> On 02/24/2016 12:24 AM, Kirti Wankhede wrote:
> >> > + vgpu_dma->size = map->size;
> >> > +
> >> > + vgpu_link_dma(vgpu_iommu, vgpu_dma);
> >>
> >> Hi Kirti & Neo,
> >>
> >> seems that no one actually setup mappings for IOMMU here?
> >>
> >
> > Hi Jike,
> >
> > Yes.
> >
> > The actual mapping should be done by the host kernel driver after calling the
> > translation/pinning API vgpu_dma_do_translate.
>
> Thanks for the reply. I mis-deleted the mail in my intel account, so
> reply with private mail account, sorry for that.
>
>
> In vgpu_dma_do_translate():
>
> for (i = 0; i < count; i++) {
> {snip}
> dma_addr_t iova = gfn_buffer[i] << PAGE_SHIFT;
> vgpu_dma = vgpu_find_dma(vgpu_iommu, iova, 0 /* size */);
>
> remote_vaddr = vgpu_dma->vaddr + iova - vgpu_dma->iova;
> if (get_user_pages_unlocked(NULL, mm, remote_vaddr, 1, 1, 0, page) == 1) {
> pfn = page_to_pfn(page[0]);
> }
> gfn_buffer[i] = pfn;
> }
>
> If I understand correctly, the purpose of above code, is given an
> array of gfns, try to pin & return associated pfns. There is still no
> IOMMU mappings here.
Yes.
> Is it supposed to be the caller who should set
> up IOMMU by DMA api such as dma_map_page(), after calling
> vgpu_dma_do_translate()?
>
Don't think you need to call dma_map_page here. Once you have the pfn available
to your GPU kernel driver, you can just go ahead to setup the mapping as you
normally do such as calling pci_map_sg and its friends.
Thanks,
Neo
>
> --
> Thanks,
> Jike
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