On 2015-07-28 15:06, Michael S. Tsirkin wrote: > On Tue, Jul 28, 2015 at 02:46:20PM +0200, Paolo Bonzini wrote: >> >> >> On 28/07/2015 12:12, Benjamin Herrenschmidt wrote: >>>>> That is an experimental feature (it's x-iommu), so it can change. >>>>> >>>>> The plan was: >>>>> >>>>> - for PPC, virtio never honors IOMMU >>>>> >>>>> - for non-PPC, either have virtio always honor IOMMU, or enforce that >>>>> virtio is not under IOMMU. >>>>> >>> I dislike having PPC special cased. >>> >>> In fact, today x86 guests also assume that virtio bypasses IOMMU I >>> believe. In fact *all* guests do. >> >> This doesn't matter much, since the only guests that implement an IOMMU >> in QEMU are (afaik) PPC and x86, and x86 does not yet promise any kind >> of stability. > > Hmm I think Jan (cc) said it was already used out there. Yes, no known issues with vt-d emulation for almost a year now. Error reporting could be improved, and interrupt remapping is still missing, but those are minor issues in this context. In my testing setups, I also have virtio devices in use, passed through to an L2 guest, but only in 1:1 mapping so that their broken IOMMU support causes no practical problems. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
