On Mon, Mar 01, 2010 at 12:14:43PM +0100, Alexander Graf wrote: > > On 14.09.2009, at 15:31, Yan Vugenfirer wrote: > > > Signed-off-by: Yan Vugenfirer <yvuge...@redhat.com> > > > > --- > > hw/virtio-pci.c | 14 ++++++++++++-- > > 1 files changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c > > index f812ab7..a0a22c4 100644 > > --- a/hw/virtio-pci.c > > +++ b/hw/virtio-pci.c > > @@ -364,8 +364,17 @@ static void virtio_map(PCIDevice *pci_dev, int > > region_num, > > static void virtio_write_config(PCIDevice *pci_dev, uint32_t address, > > uint32_t val, int len) > > { > > + VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev); > > + > > + if (PCI_COMMAND == address) { > > + if (!(val & PCI_COMMAND_MASTER)) { > > + proxy->vdev->status &= ~VIRTIO_CONFIG_S_DRIVER_OK; > > This part breaks PCI hotplug with Linux guests. > > What happens is the following: Looks like something is broken even without this patch.
> > (qemu) pci_add auto nic model=virtio,vlan=0 > - Virtio dev 1 -> write config (0) > - Virtio dev 1 -> write config (0x3) > - Virtio dev 1 -> set status explicitly to OK Why Linux doesn't enable bus mastering on this device? > > (qemu) pci_add auto storage file=/tmp/image.raw,if=virtio > - Virtio dev 1 -> write config (0x3) Why Linux touches unrelated device's config space? > -> Unset DRIVER_OK bit > -> network device becomes unresponsive > - Virtio dev 2 -> write config (0) > - Virtio dev 2 -> write config (0x3) > - Virtio dev 2 -> set status explicitly to OK > > > Please either revert this patch or provide a proper fix. > > Alex -- Gleb.