Re: [Qemu-devel] [PATCH] VirtIO: Fix QEMU crash during Windows PNP tests

[Alexander Graf <agraf@suse.de>]

On 14.09.2009, at 15:31, Yan Vugenfirer wrote:

> Signed-off-by: Yan Vugenfirer <yvugenfi@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:

(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

(qemu) pci_add auto storage file=/tmp/image.raw,if=virtio
  - Virtio dev 1 -> write config (0x3)
  -> 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