From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB08F3328F3; Sun, 11 Jan 2026 10:38:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768127921; cv=none; b=hsx53tbneFcT6byCqPjgtTK6AvYgC6zHA9snuVgJkpiUiDM9VlmzQdhqDoA9c+a59sjQSHkq8IEWFaJWe+QW2Azo+L26gpjBYD0TJ1kk+ZcK7lNdlzYiQc1sbG24AMra8DOgRHerl81aPcIz6wkvtEvfuxPfY4WQ8/gZipXqMME= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768127921; c=relaxed/simple; bh=7I4kxU/y7yloFCNkfGJ50mHLmQEVZqEXA/AJs91wt9s=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=PlbuQ18P6JbVWBQoIR8RHIu+9sY7EszUm9qdSvX1thmJInCkg8spNuB9U+m+mXoYNBggkXFRgftBwydGMaOsi8v3/ntAjli7ZlrrefRkLHVMWjHURCqvHj6bp2NbL27Zn0vP3xDi0/Jk1W717cYJo1PwRHpIPwWke7wsKj0oeYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qJfWGYjd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qJfWGYjd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 425E6C4CEF7; Sun, 11 Jan 2026 10:38:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768127921; bh=7I4kxU/y7yloFCNkfGJ50mHLmQEVZqEXA/AJs91wt9s=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qJfWGYjd+ZepmxK7UEPHv2i2vi4c7ObyN52kIRk9uUCxov7X1YtYwxGdg9Zw7tX5P EXUzn52p+KLdIAT3mmXrvWX5LOQJR870gJnOWdZ1vvmOzeuQfg0JVtz931J/IjlsA9 csvfX5wvrWKN3r0psLpyRMWyQNglTIA0KCjsA8Mm0cIxbJf1yzCCKq5fB2Eu3f5GCV YPepkJK4PAH+mVAt3r7m0YGL7syYjdRbf8/BTvcW4FRN4zxmfYVCUUWkeRUOncw1Ou RSGwpn3wZDxxu7fD45fi37+6gxwi7X8Qd2QMZkd2jIqQvAnSd2qw42yH2oFDzNwUY9 43Ykms3o4+F7Q== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vesqE-00000001Awb-3nA4; Sun, 11 Jan 2026 10:38:39 +0000 Date: Sun, 11 Jan 2026 10:38:38 +0000 Message-ID: <86v7h8l9ht.wl-maz@kernel.org> From: Marc Zyngier To: Thomas Gleixner Cc: Waiman Long , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] irqchip/gic-v3-its: Don't acquire rt_spin_lock in allocate_vpe_l1_table() In-Reply-To: <87ecnwij44.ffs@tglx> References: <20260107215353.75612-1-longman@redhat.com> <864iowmrx6.wl-maz@kernel.org> <87ms2nsqju.ffs@tglx> <86wm1qlq7l.wl-maz@kernel.org> <87ecnwij44.ffs@tglx> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: tglx@kernel.org, longman@redhat.com, bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Sun, 11 Jan 2026 09:39:07 +0000, Thomas Gleixner wrote: > > On Fri, Jan 09 2026 at 16:13, Marc Zyngier wrote: > > On Thu, 08 Jan 2026 22:11:33 +0000, > > Thomas Gleixner wrote: > >> At the point where a CPU is brought up, the topology should be known > >> already, which means this can be allocated on the control CPU _before_ > >> the new CPU comes up, no? > > > > No. Each CPU finds *itself* in the forest of redistributors, and from > > there tries to find whether it has some shared resource with a CPU > > that has booted before it. That's because firmware is absolutely awful > > and can't present a consistent view of the system. > > Groan.... > > > Anyway, I expect it could be solved by moving this part of the init to > > an ONLINE HP callback. > > Which needs to be before CPUHP_AP_IRQ_AFFINITY_ONLINE, but even that > might be to late because there are callbacks in the STARTING section, > i.e. timer, perf, which might rely on interrupts being accessible. Nah. This stuff is only for direct injection of vLPIs into guests, so as long as this is done before we can schedule a vcpu on this physical CPU, we're good. No physical interrupt is concerned with this code. > Also that patch seems to be incomplete because there is another > allocation further down in allocate_vpe_l1_table().... Yeah, I wondered why page allocation wasn't affected by this issue, but didn't try to find out. M. -- Without deviation from the norm, progress is not possible.