On Mon, 8 Sep 2014 19:05:02 +0300 "Michael S. Tsirkin" <m...@redhat.com> wrote:
> commit cc943c36faa192cd4b32af8fe5edb31894017d35 > pci: Use bus master address space for delivering MSI/MSI-X messages > breaks virtio-net for rhel6.[56] x86 guests because they don't > enable bus mastering for virtio PCI devices > > Old guests forgot to enable bus mastering, enable it > automatically on DRIVER_OK. > > Note: we should either back out the original patch from > stable or apply this one on top. > > Cc: qemu-sta...@nongnu.org > Reported-by: Greg Kurz <gk...@linux.vnet.ibm.com> > Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > --- > hw/virtio/virtio-pci.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > index ddb5da1..af937d2 100644 > --- a/hw/virtio/virtio-pci.c > +++ b/hw/virtio/virtio-pci.c > @@ -320,6 +320,8 @@ static void virtio_ioport_write(void *opaque, uint32_t > addr, uint32_t val) > if ((val & VIRTIO_CONFIG_S_DRIVER_OK) && > !(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { > proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; > + > memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, > + true); > } > break; > case VIRTIO_MSI_CONFIG_VECTOR: Cc'ing Alexey for some SLOF and early boot of the ppc64 kernel expertise. Michael, This was enough to fix virtio-net in the rhel6.5 x86 guest case. Unfortunately, this fails for rhel6.5 ppc64 because it is never called... I did some debugging: it looks like the guest kernel calls the OF quisece call to flush pending DMA and disables bus master on the virtio-blk device (PCI_COMMAND == 0x3). The guest then continues to boot and hangs... It appears that waiting for the guest to issue VIRTIO_CONFIG_S_DRIVER_OK is not enough. Since we need this for MSI to work, I tried the following and it fixes the issue: diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index af937d2..3d72aa8 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -111,9 +111,14 @@ static void virtio_pci_notify(DeviceState *d, uint16_t vector) { VirtIOPCIProxy *proxy = to_virtio_pci_proxy_fast(d); - if (msix_enabled(&proxy->pci_dev)) + if (msix_enabled(&proxy->pci_dev)) { + if (!(proxy->pci_dev.config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { + proxy->flags |= VIRTIO_PCI_FLAG_BUS_MASTER_BUG; + memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, + true); + } msix_notify(&proxy->pci_dev, vector); - else { + } else { VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus); pci_set_irq(&proxy->pci_dev, vdev->isr & 1); } If this is acceptable, I'll make it a helper and squash it into your patch. Thoughts ? -- Gregory Kurz kurzg...@fr.ibm.com gk...@linux.vnet.ibm.com Software Engineer @ IBM/Meiosys http://www.ibm.com Tel +33 (0)562 165 496 "Anarchy is about taking complete responsibility for yourself." Alan Moore.