Re: [dpdk-dev] [PATCH v4 1/3] vfio: revert change that does intr eventfd setup at probe

From: David Marchand <david.marchand@redhat.com>
To: Nithin Dabilpuram <ndabilpuram@marvell.com>
Cc: Hyong Youb Kim <hyonkim@cisco.com>,
	Thomas Monjalon <thomas@monjalon.net>,
	 Ferruh Yigit <ferruh.yigit@intel.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>,
	 Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
	John Daley <johndale@cisco.com>,
	Shahed Shaikh <shshaikh@marvell.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v4 1/3] vfio: revert change that does intr eventfd setup at probe
Date: Mon, 22 Jul 2019 21:27:12 +0200	[thread overview]
Message-ID: <CAJFAV8zZw8eWRLuXUwn3dt2F8Wq_6bk-1mkiS6Liwaqe3iwJpQ@mail.gmail.com> (raw)
In-Reply-To: <20190718143628.169623-2-ndabilpuram@marvell.com>

On Thu, Jul 18, 2019 at 4:36 PM Nithin Dabilpuram
<ndabilpuram@marvell.com> wrote:
>
> This reverts commit 89aac60e0be9ed95a87b16e3595f102f9faaffb4.
> "vfio: fix interrupts race condition"
>
> The above mentioned commit moves the interrupt's eventfd setup
> to probe time but only enables one interrupt for all types of
> interrupt handles i.e VFIO_MSI, VFIO_LEGACY, VFIO_MSIX, UIO.
> It works fine with default case but breaks below cases specifically
> for MSIX based interrupt handles.
>
> * Applications like l3fwd-power that request rxq interrupts
>   while ethdev setup.
> * Drivers that need > 1 MSIx interrupts to be configured for
>   functionality to work.
>
> VFIO PCI for MSIx expects all the possible vectors to be setup up
> when using VFIO_IRQ_SET_ACTION_TRIGGER so that they can be
> allocated from kernel pci subsystem. Only way to increase the number
> of vectors later is first free all by using VFIO_IRQ_SET_DATA_NONE
> with action trigger and then enable new vector count.

Indeed, this is the part that I had missed.
Ok for this revert.
A bit sad to see the coding style issues back :-).

--
David Marchand