Received-SPF: pass (google.com: domain of linux-kernel+bounces-202909-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Wed, 5 Jun 2024 13:22:49 -0300
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Fred Griffoul <fgriffo@amazon.co.uk>
Cc: griffoul@gmail.com, Alex Williamson <alex.williamson@redhat.com>,
	Yi Liu <yi.l.liu@intel.com>, Kevin Tian <kevin.tian@intel.com>,
	Eric Auger <eric.auger@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Christian Brauner <brauner@kernel.org>,
	Ankit Agrawal <ankita@nvidia.com>,
	Reinette Chatre <reinette.chatre@intel.com>,
	Ye Bin <yebin10@huawei.com>, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] vfio/pci: add msi interrupt affinity support
Message-ID: <20240605162249.GE791043@ziepe.ca>
References: <20240605155509.53536-1-fgriffo@amazon.co.uk>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240605155509.53536-1-fgriffo@amazon.co.uk>

On Wed, Jun 05, 2024 at 03:55:05PM +0000, Fred Griffoul wrote:
> The usual way to configure a device interrupt from userland is to write
> the /proc/irq/<irq>/smp_affinity or smp_affinity_list files. When using
> vfio to implement a device driver or a virtual machine monitor, this may
> not be ideal: the process managing the vfio device interrupts may not be
> granted root privilege, for security reasons. Thus it cannot directly
> control the interrupt affinity and has to rely on an external command.

For a long time I've been beating a drum that people need to stop
using /proc/irq/../smp_affinity, so I like this idea :)

Jason