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

[Alexander Graf]

On 02.03.2010, at 12:05, Michael S. Tsirkin wrote:

> 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 <address@hidden>
>>>>>> 
>>>>>> ---
>>>>>> 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?

Yes, it works with the patch applied. It's still missing a capability though 
:-).


Alex