From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-s390-owner@vger.kernel.org>
Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48117 "EHLO
        us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK)
        by vger.kernel.org with ESMTP id S1727512AbgKSLnk (ORCPT
        <rfc822;linux-s390@vger.kernel.org>);
        Thu, 19 Nov 2020 06:43:40 -0500
Date: Thu, 19 Nov 2020 12:43:26 +0100
From: Cornelia Huck <cohuck@redhat.com>
Subject: Re: [RFC PATCH 2/2] vfio-ccw: Wire in the request callback
Message-ID: <20201119124326.0345a353.cohuck@redhat.com>
In-Reply-To: <20201117032139.50988-3-farman@linux.ibm.com>
References: <20201117032139.50988-1-farman@linux.ibm.com>
        <20201117032139.50988-3-farman@linux.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
List-ID: <linux-s390.vger.kernel.org>
To: Eric Farman <farman@linux.ibm.com>
Cc: Kirti Wankhede <kwankhede@nvidia.com>, Alex Williamson <alex.williamson@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, linux-s390@vger.kernel.org, kvm@vger.kernel.org

On Tue, 17 Nov 2020 04:21:39 +0100
Eric Farman <farman@linux.ibm.com> wrote:

> The device is being unplugged, so pass the request to userspace to
> ask for a graceful cleanup. This should free up the thread that
> would otherwise loop waiting for the device to be fully released.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  drivers/s390/cio/vfio_ccw_ops.c     | 26 ++++++++++++++++++++++++++
>  drivers/s390/cio/vfio_ccw_private.h |  4 ++++
>  include/uapi/linux/vfio.h           |  1 +
>  3 files changed, 31 insertions(+)
> 

(...)

> @@ -607,6 +611,27 @@ static ssize_t vfio_ccw_mdev_ioctl(struct mdev_device *mdev,
>  	}
>  }
>  
> +/* Request removal of the device*/
> +static void vfio_ccw_mdev_request(struct mdev_device *mdev, unsigned int count)
> +{
> +	struct vfio_ccw_private *private = dev_get_drvdata(mdev_parent_dev(mdev));
> +
> +	if (!private)
> +		return;
> +
> +	if (private->req_trigger) {
> +		if (!(count % 10))
> +			dev_notice_ratelimited(mdev_dev(private->mdev),
> +					       "Relaying device request to user (#%u)\n",
> +					       count);
> +
> +		eventfd_signal(private->req_trigger, 1);
> +	} else if (count == 0) {
> +		dev_notice(mdev_dev(private->mdev),
> +			   "No device request channel registered, blocked until released by user\n");
> +	}
> +}

This looks like the vfio-pci request handler, so probably good :)

Still have to read up on the QEMU side, but a LGTM for now.