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. > > > > (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.