linux-kernel - Re: [PATCH] irqchip/gic-v3-its: Don't need VSYNC if VMAPP with {V, Alloc}=={0, x}

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Message-ID: <86frw3t27r.wl-maz@kernel.org>
Date: Wed, 03 Apr 2024 07:00:40 +0100
From: Marc Zyngier <maz@...nel.org>
To: Tangnianyao <tangnianyao@...wei.com>
Cc: <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<guoyang2@...wei.com>,
	<wangwudi@...ilicon.com>
Subject: Re: [PATCH] irqchip/gic-v3-its: Don't need VSYNC if VMAPP with {V, Alloc}=={0, x}

On Wed, 03 Apr 2024 03:18:51 +0100,
Tangnianyao <tangnianyao@...wei.com> wrote:
> 
> 
> 
> On 4/2/2024 21:43, Marc Zyngier wrote:
> > On Tue, 02 Apr 2024 14:32:40 +0100,
> > Tangnianyao <tangnianyao@...wei.com> wrote:
> >>
> >>
> >> Thank you for quick fix, it would be great to remove this VSYNC. ITS handling VSYNC unmap
> >> vpeid may waste some time, trigger exception and needed to be
> >> handled.
> > Do you actually see an exception being delivered from this?
> >
> > In any case, feel free to respin the patch after having tested this
> > diff, with the commit message fixed and a Fixes: tag attached to it.
> 
> In our developing implemenation, ITS would report RAS when doing vsync
> and reaching an invalid vpe table entry. It is reasonable to report RAS, right?

If a RAS error is the only reporting method you have, then I suspect
you don't have much of a choice (the pseudocode indicates an IMPDEF
SError for VSYNC). Shame this wasn't caught earlier.

> It just reports, and kernel can still run normally regardless of
> this RAS message.

That really depends on the policy behind RAS errors.

Looking forward to your respinning of this patch.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.