From: Michael S. Tsirkin <m...@redhat.com> 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. For the same reason, rhel6.[56] ppc64 guests cannot boot on a virtio-blk disk anymore.
Old guests forgot to enable bus mastering, enable it automatically on DRIVER (ppc64 guests may never reach DRIVER_OK). We also need to prevent these old guests to disable bus mastering (this happens when the driver probes the device). And we must also re-enable bus mastering after migration. Cc: qemu-sta...@nongnu.org Reported-by: Greg Kurz <gk...@linux.vnet.ibm.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> [ old guest detection on DRIVER, squashed patch from Michael S. Tsirkin to re-enable bus mastering, Greg Kurz <gk...@linux.vnet.ibm.com> ] Tested-by: Cedric Le Goater <c...@fr.ibm.com> Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com> --- hw/virtio/virtio-pci.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index ddb5da1..f981841 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -317,9 +317,11 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val) /* Linux before 2.6.34 sets the device as OK without enabling the PCI device bus master bit. In this case we need to disable some safety checks. */ - if ((val & VIRTIO_CONFIG_S_DRIVER_OK) && + if ((val & VIRTIO_CONFIG_S_DRIVER) && !(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: @@ -473,10 +475,14 @@ static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, pci_default_write_config(pci_dev, address, val, len); if (range_covers_byte(address, len, PCI_COMMAND) && - !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER) && - !(proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG)) { - virtio_pci_stop_ioeventfd(proxy); - virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); + !(pci_dev->config[PCI_COMMAND] & PCI_COMMAND_MASTER)) { + if (proxy->flags & VIRTIO_PCI_FLAG_BUS_MASTER_BUG) { + memory_region_set_enabled(&proxy->pci_dev.bus_master_enable_region, + true); + } else { + virtio_pci_stop_ioeventfd(proxy); + virtio_set_status(vdev, vdev->status & ~VIRTIO_CONFIG_S_DRIVER_OK); + } } } @@ -890,6 +896,8 @@ static void virtio_pci_vmstate_change(DeviceState *d, bool running) if ((vdev->status & 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); } virtio_pci_start_ioeventfd(proxy); } else {