Re: [Qemu-devel] [PATCH v8 11/12] vfio: register aer resume notification handler for aer resume

From: Zhou Jie <zhoujie2011@cn.fujitsu.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: qemu-devel@nongnu.org, fan.chen@easystack.cn,
	izumi.taku@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com,
	mst@redhat.com, Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH v8 11/12] vfio: register aer resume notification handler for aer resume
Date: Sun, 12 Jun 2016 10:38:33 +0800	[thread overview]
Message-ID: <30d1cd95-7f67-29cf-c55e-0565364d89ff@cn.fujitsu.com> (raw)
In-Reply-To: <20160527100655.60db8206@t450s.home>

Hi, Alex

> It seems like we have a number of questions open in the thread with MST
> from the previous version, particularly whether we should actually drop
> the resume notifier and block the reset in the kernel.  The concern
> being that it's not very well specified what we can and cannot do
> between the error interrupt and the resume interrupt.  We'd probably
> need some other indicate of whether the host has this capability,
> perhaps a flag in vfio_device_info.  Appreciate your opinions there.
> Thanks,
>
> Alex

Have you had a conclusion with MST?

How about the process like following?
1. Detect support for VFIO reset blocking.
    Maybe use vfio_device_info.
2. Immediately notify the VM on error detected.
3. Invoke ioctl(VFIO_DEVICE_PCI_HOT_RESET).
    If kernel is doing reset, then block in ioctl.

    Can I ignore the resume notifier?
    else
    Shall ioctl block until after receiving resume notification?

Sincerely
Zhou Jie