Re: [Qemu-devel] [PATCH v9 08/11] vfio: vote the function 0 to do host bus reset when aer occurred

[Cao jin <caoj.fnst@cn.fujitsu.com>]

帆，昨天电话里面好像还有个点没清楚，这个点也在这个patch里，不知道我理解 
的对不对，有空的时候请帮斧正下：
（已经理解，对于uncorrectable error, driver里是会做reset link的，也就是 
设置pci bridge的secondary bus reset的那个bit）

On 07/19/2016 03:38 PM, Zhou Jie wrote:
> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
>
> Due to all devices assigned to VM on the same way as host if enable
> aer, so we can easily do the hot reset by selecting the function #0
> to do the hot reset.
>
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> ---
>   hw/vfio/pci.c | 14 ++++++++++++++
>   hw/vfio/pci.h |  1 +
>   2 files changed, 15 insertions(+)
>
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 8bcb26b..0521652 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1924,6 +1924,8 @@ static void vfio_check_hot_bus_reset(VFIOPCIDevice *vdev, Error **errp)
>       /* List all affected devices by bus reset */
>       devices = &info->devices[0];
>
> +    vdev->single_depend_dev = (info->count == 1);
> +

info->count == 1 表示hot reset时候不会影响别的设备(1是该设备自己)，那就 
是说，被 passthrough 的 function 所在的物理 bus 下，有且只有这一个 
function (也就是非multi-function设备的意思吗？)

>       /* Verify that we have all the groups required */
>       for (i = 0; i < info->count; i++) {
>           PCIHostDeviceAddress host;
> @@ -3120,6 +3122,18 @@ static void vfio_pci_reset(DeviceState *dev)
>
>       trace_vfio_pci_reset(vdev->vbasedev.name);
>
> +    if (vdev->features & VFIO_FEATURE_ENABLE_AER) {
> +        PCIDevice *br = pci_bridge_get_device(pdev->bus);
> +
> +        if ((pci_get_word(br->config + PCI_BRIDGE_CONTROL) &
> +             PCI_BRIDGE_CTL_BUS_RESET)) {
> +            if (pci_get_function_0(pdev) == pdev) {
> +                vfio_pci_hot_reset(vdev, vdev->single_depend_dev);
> +            }
> +            return;
> +        }
> +    }
> +


有点不明白为什么需要这段，或者是想问：对于两个vfio passthrough的 
function，不同function发生aer时候，处理流程是不一样的，为啥呢？

-- 
Yours Sincerely,

Cao jin