----- Original Message -----
>
>
> ----- Original Message -----
> > .snip.
> > > > > This raises two issues:
> > > > > 1) swiotlb_tlb_unmap_single fails to check whether the index
> > > > > generated
> > > > > from the dma_addr is in range of the io_tlb_orig_addr array.
> > > > That is fairly simple to implement I would think. That is it can check
> > > > that the dma_addr is from the PA in the io_tlb pool when SWIOTLB=force
> > > > is used.
> > >
> > >
> > > I'm not sure this can fix all the cases. It looks to me we should map
> > > descriptor coherent but readonly (which is not supported by current DMA
> > > API).
> >
> > I think I am missing something obvious here. The attacker is the
> > hypervisor,
> > aka
> > the owner of the VirtIO device (ring0). The attacker is the one that
> > provides the addr/len - having that readonly from a guest perspective
> > does not change the fact that the hypervisor can modify the memory range
> > by mapping it via a different virtual address in the hypervisor? (aka
> > aliasing it).
>
> Right, but if we allow hypervisor to provide arbitrary addr/len, does
> it mean hypervisor can read encrypted content of encrypted memory of
> guest through swiotlb?
>
> Thanks
Actually not. I think you're right.
Thanks
>
> > >
> > > Otherwise, device can modify the desc[i].addr/desc[i].len at any time to
> > > pretend a valid mapping.
> >
> > With the swiotlb=force as long as addr/len are within the PA boundaries
> > within the SWIOTLB pool this should be OK?
> >
> > After all that whole area is in cleartext and visible to the attacker.
> >
> >
>
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