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Date: Thu, 24 Mar 2016 16:54:28 -0600
From: Alex Williamson <alex.williamson@redhat.com>
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Subject: Re: [Qemu-devel] [patch v5 11/12] vfio: device may stuck in D3 when
 doing aer recovery
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To: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: chen.fan.fnst@cn.fujitsu.com, izumi.taku@jp.fujitsu.com, qemu-devel@nongnu.org, mst@redhat.com

On Wed, 23 Mar 2016 18:12:06 +0800
Cao jin <caoj.fnst@cn.fujitsu.com> wrote:

> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> when a physical device aer occurred, the device state probably
> is not in D0 in a short time, if we recover the device quickly.
> we may stuck in D3 state when force to change device state to D0.
> we may need to wait for a short time to inject the error to guest.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> ---
>  hw/vfio/pci.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 25fc095..5216e7f 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2658,6 +2658,9 @@ static void vfio_err_notifier_handler(void *opaque)
>          msg.severity = isfatal ? PCI_ERR_ROOT_CMD_FATAL_EN :
>                                   PCI_ERR_ROOT_CMD_NONFATAL_EN;
>  
> +        /* wait a bit to ensure aer device is ready */
> +        usleep(2 * 1000);

Where does this number come from?  Why would the device be in D3?  I
don't understand this at all.

> +
>          pcie_aer_msg(dev, &msg);
>          return;
>      }