vp_init_simple: enable PCI bus-mastering before relying on DMA.

An analogous change was made in the LSI scsi driver, commit
7d052575258ad2fc487ca3f9a6b62eff1b767900. Qemu works around guests that don't
correctly enable PCI bus mastering before using virtio queues' DMA (search for
VIRTIO_PCI_BUG_BUS_MASTER / VIRTIO_PCI_FLAG_BUS_MASTER_BUG ), but it'd be
better to be correct.

Signed-off-by: Eric Northup <digitaleric@google.com>

diff --git a/src/hw/virtio-pci.c b/src/hw/virtio-pci.c
index a38250485a6d4d24c33eb1050f46ec3b31368766..b9b3ab1e31935d7df10b9878550fabb2ed30b344 100644 (file)
--- a/src/hw/virtio-pci.c
+++ b/src/hw/virtio-pci.c
@@ -90,6 +90,7 @@ u16 vp_init_simple(u16 bdf)
         PCI_BASE_ADDRESS_IO_MASK;
 
     vp_reset(ioaddr);
+    pci_config_maskw(bdf, PCI_COMMAND, 0, PCI_COMMAND_MASTER);
     vp_set_status(ioaddr, VIRTIO_CONFIG_S_ACKNOWLEDGE |
                   VIRTIO_CONFIG_S_DRIVER );
     return ioaddr;