On Thu, Dec 14, 2017 at 03:46:56PM +0000, Stefan Hajnoczi wrote: > On Wed, Dec 13, 2017 at 10:50:11PM +0100, Maxime Coquelin wrote: > > On 12/13/2017 09:08 PM, Stefan Hajnoczi wrote: > > > On Wed, Dec 13, 2017 at 3:01 PM, Michael S. Tsirkin <m...@redhat.com> > > > wrote: > > > > On Wed, Dec 13, 2017 at 12:35:21PM +0000, Stefan Hajnoczi wrote: > > > > > I'm not saying that DPDK should use libvhost-user. I'm saying that > > > > > it's > > > > > easy to add vfio vhost-pci support (for the PCI adapter I described) > > > > > to > > > > > DPDK. This patch series would require writing a completely new slave > > > > > for vhost-pci because the device interface is so different from > > > > > vhost-user. > > > > > > > > The main question is how appropriate is the vhost user protocol > > > > for passing to guests. And I am not sure at this point. > > > > > > > > Someone should go over vhost user messages and see whether they are safe > > > > to pass to guest. If most are then we can try the transparent approach. > > > > If most aren't then we can't and might as well use the proposed protocol > > > > which at least has code behind it. > > > > > > I have done that: > > > > > ... > > > * VHOST_USER_SET_MEM_TABLE > > > > > > Set up BARs before sending a VHOST_USER_SET_MEM_TABLE to the guest. > > > > It would require to filter out userspace_addr from the payload not to > > leak other QEMU process VAs to the guest. > > QEMU's vhost-user master implementation is insecure because it leaks > QEMU process VAs. This also affects vhost-user host processes, not just > vhost-pci. > > The QEMU vhost-user master could send an post-IOMMU guest physical > addresses whereever the vhost-user protocol specification says "user > address". That way no address space information is leaked although it > does leak IOMMU mappings. > > If we want to hide the IOMMU mappings too then we need another logical > address space (kind a randomized ramaddr_t). > > Anyway, my point is that the current vhost-user master implementation is > insecure and should be fixed. vhost-pci doesn't need to worry about > this issue. > > Stefan
I was going to make this point too. It does not look like anyone uses userspace_addr. It might have been a mistake to put it there - maybe we should have reused it for map offset. It does not look like anyone uses this for anything. How about we put zero, or a copy of the GPA there? -- MST
