Re: [PATCH 1/7] vfio/pci: Disable auto-enable of exclusive INTx IRQ

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 7 Mar 2024 08:39:16 +0000
"Tian, Kevin" <kevin.tian@intel.com> wrote:

> > From: Alex Williamson <alex.williamson@redhat.com>
> > Sent: Thursday, March 7, 2024 5:15 AM
> > 
> > Currently for devices requiring masking at the irqchip for INTx, ie.
> > devices without DisINTx support, the IRQ is enabled in request_irq()
> > and subsequently disabled as necessary to align with the masked status
> > flag.  This presents a window where the interrupt could fire between
> > these events, resulting in the IRQ incrementing the disable depth twice.
> > This would be unrecoverable for a user since the masked flag prevents
> > nested enables through vfio.
> > 
> > Instead, invert the logic using IRQF_NO_AUTOEN such that exclusive INTx
> > is never auto-enabled, then unmask as required.
> > 
> > Fixes: 89e1f7d4c66d ("vfio: Add PCI device driver")
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>  
> 
> CC stable?

I've always found that having a Fixes: tag is sufficient to get picked
up for stable, so I typically don't do both.  If it helps out someone's
process I'd be happy to though.  Thanks,

Alex