Re: [PATCH v1 0/5] Enable hotplug in vfio

From: "Gaëtan Rivet" <gaetan.rivet@6wind.com>
To: Jeff Guo <jia.guo@intel.com>
Cc: stephen@networkplumber.org, bruce.richardson@intel.com,
	ferruh.yigit@intel.com, konstantin.ananyev@intel.com,
	jingjing.wu@intel.com, thomas@monjalon.net, motih@mellanox.com,
	matan@mellanox.com, harry.van.haaren@intel.com,
	qi.z.zhang@intel.com, shaopeng.he@intel.com,
	bernard.iremonger@intel.com, arybchenko@solarflare.com,
	jblunck@infradead.org, shreyansh.jain@nxp.com, dev@dpdk.org,
	helin.zhang@intel.com
Subject: Re: [PATCH v1 0/5] Enable hotplug in vfio
Date: Mon, 20 Aug 2018 11:15:33 +0200	[thread overview]
Message-ID: <20180820091533.yl2wzmvzfxqwo2po@bidouze.vm.6wind.com> (raw)
In-Reply-To: <1534503091-31910-1-git-send-email-jia.guo@intel.com>

Hi Jeff,

On Fri, Aug 17, 2018 at 06:51:26PM +0800, Jeff Guo wrote:
> As we may know that the process of hotplug is different between igb_uio
> and vfio. For igb_uio, it could use uevent notification and memory
> failure handle mechanism for hotplug. But for vfio, when device is be
> hotplug-out, the uevent can not be detected immediately, because of the
> vfio kernel module will use a special mechanism to guaranty the pci
> device would not be deleted until the user space release the resources,
> so it will use another event “req notifier” at first to notify user space
> to release resources for hotplug.
> 
> This patch will add a new interrupt type of req notifier in eal interrupt,
> and add the new interrupt handler in pci device to handle the req device
> event. When the req notifier be detected, it can trigger the device event
> callback process to process for hotplug. With this mechanism, hotplug
> could be enable in vfio.
> 

The REQ event seems VFIO specific.
Why not leave it within the PCI bus, around the vfio glue, and leave the
EAL unmodified?

> Jeff Guo (5):
>   eal: add a new req notifier to eal interrupt
>   eal: add a new req event to device event
>   eal: modify device event callback process func
>   pci: add req handler field to generic pci device
>   vfio: enable vfio hotplug by req notifier handler
> 
>  drivers/bus/pci/linux/pci_vfio.c                   | 104 +++++++++++++++++++++
>  drivers/bus/pci/pci_common.c                       |  10 ++
>  drivers/bus/pci/rte_bus_pci.h                      |   1 +
>  lib/librte_eal/common/eal_common_dev.c             |   5 +-
>  lib/librte_eal/common/eal_private.h                |  12 ---
>  lib/librte_eal/common/include/rte_dev.h            |  20 +++-
>  lib/librte_eal/common/include/rte_eal_interrupts.h |   1 +
>  lib/librte_eal/linuxapp/eal/eal_dev.c              |   2 +-
>  lib/librte_eal/linuxapp/eal/eal_interrupts.c       |  71 ++++++++++++++
>  lib/librte_ethdev/rte_ethdev.c                     |   3 +-
>  10 files changed, 212 insertions(+), 17 deletions(-)
> 
> -- 
> 2.7.4
> 

-- 
Gaëtan Rivet
6WIND