linux-kernel - Re: [PATCH V2] irqchip/gic-v4.1:Check whether indirect table is supported in allocate_vpe_l1

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Message-ID: <8634891tyl.wl-maz@kernel.org>
Date: Fri, 26 Sep 2025 09:47:14 +0100
From: Marc Zyngier <maz@...nel.org>
To: Nianyao Tang <tangnianyao@...wei.com>
Cc: <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<guoyang2@...wei.com>,
	<wangwudi@...ilicon.com>,
	<wangzhou1@...ilicon.com>,
	<jiangkunkun@...wei.com>,
	<guozicheng3@...ilicon.com>
Subject: Re: [PATCH V2] irqchip/gic-v4.1:Check whether indirect table is supported in allocate_vpe_l1_table

On Thu, 18 Sep 2025 15:15:57 +0100,
Nianyao Tang <tangnianyao@...wei.com> wrote:
> 
> In allocate_vpe_l1_table, it allocates a new vpe table without checking
> whether indirect table is supported.
> ARM allows vendors to support only flat tables. Let's first check if
> indirect tables are supported before using it.
> 
> Signed-off-by: Nianyao Tang <tangnianyao@...wei.com>

As I understand it, this is for the same machines that also requires
[1] and [2] to be able to use vLPIs and vSGIs.

I seriously doubt that we want *any* of it (creating userspace ABI to
deal with a broken design is not something I'm keen on).

Frankly, you should consider disabling GICv4.1 on these machines, and
stick with GICv3 (which I assume works correctly).

Thanks,

	M.

[1] https://lore.kernel.org/r/20250825023954.3516381-1-wangzhou1@hisilicon.com
[2] https://lore.kernel.org/r/20250909110615.129179-1-wangzhou1@hisilicon.com

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