Re: [Xen-devel] [PATCH] xen/arm: vgic-v3: Fix the typo of GICD IRQ active status range

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Sat, 28 Dec 2019, Wei Xu wrote:
> Hi Julien,
> 
> On 2019/12/28 16:09, Julien Grall wrote:
> > Hi,
> > 
> > On 28/12/2019 03:08, Wei Xu wrote:
> > > This patch fixes the typo about the active status range of an IRQ
> > > via GICD. Otherwise it will be failed to handle the mmio access and
> > > inject a data abort.
> > I have seen a patch similar from NXP a month ago and I disagreed on the
> > approach.
> > 
> > If you look at the context you modifed, it says that reading ACTIVER is not
> > supported. While I agree the behavior is not consistent accross ACTIVER,
> > injecting a data abort is a perfectly fine behavior to me (though not spec
> > compliant) as we don't implement the registers correctly.
> > 
> > I guess you are sending this patch, because you tried Linux 5.4 (or later)
> > on Xen, right? Linux has recently began to read ACTIVER to check whether an
> > IRQ is active at the HW level during the synchronizing of the IRQS. From my
> > understanding, this is used because there is a window where the interrupt is
> > active at the HW level but the Linux IRQ subsystem is not aware of it.
> > 
> > While the patch below will allow Linux 5.4 to not crash, it is not going to
> > make it fly very far because of the above. So I am rather not happy with
> > persuing with returning 0.
> > 
> 
> Yes, I am using Linux 5.5-rc2 :)
> Got it and thanks for the explanation.
> I am not insistent on this and OK to wait for the update.
> Thanks and have a very happy new year!

Hi Wei,

what do you do to reproduce the issue? Are you just booting Linux
5.5-rc2 as dom0 and seeing the issue during boot, or are you doing
something specific?

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