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Date: Mon, 10 Jun 2024 18:31:49 +0200
From: Michal =?utf-8?Q?Koutn=C3=BD?= <mkoutny@suse.com>
To: Fred Griffoul <fgriffo@amazon.co.uk>
Cc: griffoul@gmail.com, Catalin Marinas <catalin.marinas@arm.com>, 
	Will Deacon <will@kernel.org>, Alex Williamson <alex.williamson@redhat.com>, 
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Subject: Re: [PATCH v5 0/2] vfio/pci: add msi interrupt affinity support
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Hello Fred.

On Mon, Jun 10, 2024 at 12:57:06PM GMT, Fred Griffoul <fgriffo@amazon.co.uk> 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.

External commands something privileged? (I'm curious of an example how
this is setup.)

> The affinity argument must be a subset of the process cpuset, otherwise
> an error -EPERM is returned.

I'm not sure you want to look at task's cpuset mask for this purposes.

Consider setups without cpuset or a change of (cpuset) mask anytime
during lifetime of the task...

Michal

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