On Wed, Apr 27, 2016 at 04:58:51PM +0200, Joerg Roedel wrote: > On Wed, Apr 27, 2016 at 05:54:57PM +0300, Michael S. Tsirkin wrote: > > Point is, QEMU is not the only virtio implementation out there. > > So we can't know no virtio implementations have an IOMMU as long as > > linux supports this IOMMU. > > virtio always used physical addresses since it was born and if it > > changes that it must do this in a way that does not break existing > > users. > > FWIW, virtio in qemu can continue to just use physical addresses. But > qemu needs to advertise that fact correctly to the OS in the DMAR table. > This way old kernels (where virtio does not use DMA-API) will also > continue to work on the fixed qemu. > > > > Joerg
It's not clear it can do this since DMAR tables seem to assume a given slot is either bypassing IOMMU or going through it. QEMU allows reusing same slot for virtio and non-virtio devices. Besides, this patch is not about it, it's a flag for QEMU to tell guest that it can trust DMAR tables. -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
