On Tue, Mar 02, 2010 at 12:03:15PM +0100, Alexander Graf wrote: > > On 02.03.2010, at 11:09, Michael S. Tsirkin wrote: > > > On Mon, Mar 01, 2010 at 01:26:37PM +0200, Gleb Natapov wrote: > >> 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? > > > > I fixed this, and Rusty said he has applied the patch, > > but it seems the patch got lost later: > > > > http://lkml.org/lkml/2009/11/29/73 > > > > Alexander, could you please check whether applying > > this patch fixes hotplug for you? > > If yes I will queue it up for 2.6.34. > > So we're looking at a guest bug?
Donnu. Does it work with the patch applied? > It's still a qemu regression then. This configuration used to work > with 0.10. There should at least be a feature bit from the guest > saying "I'm good with bus mastering", so we can enable the check only > for those. > Alex