On Fri, Jan 16, 2015 at 09:32:26AM +0100, Gerd Hoffmann wrote: > Hi, > > > > * I'd like to see some more flexibility in the pci bar layout. Stuff > > > I have in mind: > > > - New devices which don't need a legacy bar can use bar 0 for > > > modern. > > > - One MMIO bar is enough, we can place both virtio regions and > > > msi-x regions there. I'd suggest to add msi-x sub-regions to > > > the modern bar. > > > > Why exactly? It seems simpler to separate things, extra BARs > > have no cost. > > Well, there are only six BARs. legacy bar, modern mmio bar, msi-x bar, > modern io bar (for fast isr). That already four out of six ... So? If we need to add another bar, we'll change things. > We have a mmio bar, which we partition into subregions for virtio-1.0 > anyway. Also placing msi-x there is a single msix_init() call. xhci is > doing that too: > > 00000000febf0000-00000000febf3fff (prio 1, RW): xhci > 00000000febf0000-00000000febf003f (prio 0, RW): capabilities > 00000000febf0040-00000000febf043f (prio 0, RW): operational > 00000000febf0440-00000000febf044f (prio 0, RW): usb3 port #1 > 00000000febf0450-00000000febf045f (prio 0, RW): usb3 port #2 > 00000000febf0460-00000000febf046f (prio 0, RW): usb3 port #3 > 00000000febf0470-00000000febf047f (prio 0, RW): usb3 port #4 > 00000000febf0480-00000000febf048f (prio 0, RW): usb2 port #1 > 00000000febf0490-00000000febf049f (prio 0, RW): usb2 port #2 > 00000000febf04a0-00000000febf04af (prio 0, RW): usb2 port #3 > 00000000febf04b0-00000000febf04bf (prio 0, RW): usb2 port #4 > 00000000febf1000-00000000febf121f (prio 0, RW): runtime > 00000000febf2000-00000000febf281f (prio 0, RW): doorbell > 00000000febf3000-00000000febf30ff (prio 0, RW): msix-table > 00000000febf3800-00000000febf3807 (prio 0, RW): msix-pba > However that one is non prefetheable, and I prefer putting virtio caps in a prefetcheable bar. > > > * What is the reason for making the modern bar 8M in size? Looks a bit > > > excessive, given that only 64k or so of that are actually used ... > > > > I use a page per VQ for architectures that can locate the offset of the > > accessed page that triggered EPT violation faster than the offset within > > page. I think this is the case for SVM. > > 8M still looks excessive, given that we typically have a small number of > queues per device. Do you allocate address space for the maximum > possible number of queues unconditionally? Yes, simpler this way. I'll check if I can find the real # of VQs. > > > virtio-scsi seems to be broken, at least my usual fedora guest didn't > > > boot up from virtio-scsi disk when using a guest kernel with this patch > > > series applied. > > > > I'll re-test. Do other devices work for you? Thanks! > > Didn't came very far yet in my testing due to the guest not booting. Try virtio-blk - that worked for me. > I > plan to try other storage for the image, but didn't found the time yet. > > I've tried to boot a F21 live iso with virtio-net (legacy guest driver > obviously), which seems to work ok in light testing. > > BTW: is there a tool (or pciutils patch) which can decode the virtio > capabilities? > > cheers, > Gerd > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
