From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793895606; b=yS83vGExj1f6D+OFVD24ZZSMDaJXSiL/sxMtMfFHFmQG+A5gHRxJggEPB5leux3h0L0c f6NpKZ0gHzeZ6B/pTW6zV3nrH5x93sDsk9Nh55oc2jMB3oOZmZQ9UvIV8TcNW7LQZ5OhP A3FAjL7lAl/KWyremZVCP/T3PAm68PaiFqyRNZ5t2hJLV2Ik2MeetN8WmQwslgICvTsJe 9itQI8BsoedbX87AsASMxDzJK8nAXFtvqUpNC+7vsD2MUmy6kpqXNEzOXSgG0EfI86zSH o3465t8FALqIogHcOKk1RC7UbyVLaLovZ98mWfUyuUy2BnREMsUX2UQqrZAdLI5rexg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793895606; h=Received:DKIM-Signature:Received:Date:Message-ID:From:To:Cc:Subject: In-Reply-To:References:User-Agent:MIME-Version:Content-Type: X-SA-Exim-Connect-IP:X-SA-Exim-Rcpt-To:X-SA-Exim-Mail-From: X-SA-Exim-Scanned; bh=rAfgYJb3CU0ZmVV1RZG4jgQB2Ko2DnWepqbK4ErMKrU=; b=3GkYYkg/i4pQHwv2uWrEhahb+DzJB6niyw4KzkKfii28PTnCpF2mV/t68KiLSqgpfZj6 onz5kn5zKCXKgv2g8gMkzpVDPt/1A0bKA3Du2p85lPZyIdU+xiQGuhWMmWwyAOtZXb1no jm1dsG6QePiA6IJV9wL9vF0iBiXMdSPF8y3MQ2qaWvPTGhUMlZOKbCMnLmk3v7uLduInm qNkaQA1k8/6Q1ZVIwoGZEOjRPv2a5OnQqbFTl86C7zTVbDUqR1Hmu+0xVbK4WqeqprOfy /N9RHkx1uwtsPi1pto9MROoVMma7k3cyoM6PfjgK7nyGjzUo5saEiZiQ4e5L8FlagrA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kqGX0Qru; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46C6A606A33F; Thu, 5 Nov 2026 16:20:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kqGX0Qru Received: by smtp.kernel.org (Postfix) with ESMTPSA id B740A1F0093A; Thu, 5 Nov 2026 16:20:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793895605; bh=rAfgYJb3CU0ZmVV1RZG4jgQB2Ko2DnWepqbK4ErMKrU=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=kqGX0Qru58U+OHeadfWAMb6N1IIP8ucW5R79h/yfRES/lFapRAfnom+jxQL2+D3KV 3VQbn8o338D9ZOjUnPRfSX9vx3or6dxyvJDRfb8uWtUPdtBR1YkqA8RDo+wLHUnYhD SNKeQKf9n/HutLT2t0XYRKog0ysFPvZ1lye/wN0HCNBMvjQH3Fs6cJxkrYv8hOlO2P fawYH0KgT3QqQvH5C6FRD45wGODhb3YMbpl9C6RamZcNoZb9DyM32ieGHf6D7TfVFm AcKZwanrXLScxtreb6moYqjqIjr8iAVyG8uq0LOftKSGgBAYij0D4VGSlvcplT2XAz 3CU89qOPiF6Ow== 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 1xP0C3-0000000BiuJ-000O; Thu, 05 Nov 2026 16:20:03 +0000 Date: Thu, 05 Nov 2026 16:20:01 +0000 Message-ID: <86zevn1c9a.wl-maz@kernel.org> From: Marc Zyngier To: "Aneesh Kumar K.V (Arm)" Cc: linux-coco@lists.linux.dev, Andrew Morton , Baoquan He , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Catalin Marinas , Christian =?UTF-8?B?S8O2bmln?= , Jason Gunthorpe , Joerg Roedel , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , Russell King , Benjamin Gaignard , Brian Starkey , John Stultz , Mark Rutland , Radu Rendec , "T.J. Mercier" , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Kiryl Shutsemau , Rick Edgecombe , "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Paolo Bonzini , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, linaro-mm-sig@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, patches@lists.linux.dev Subject: Re: [PATCH v9 14/14] irqchip/gic-v3-its: Preallocate VPE L1 tables In-Reply-To: <20261104164555.3555725-15-aneesh.kumar@kernel.org> References: <20261104164555.3555725-1-aneesh.kumar@kernel.org> <20261104164555.3555725-15-aneesh.kumar@kernel.org> 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) X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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: aneesh.kumar@kernel.org, linux-coco@lists.linux.dev, akpm@linux-foundation.org, baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, catalin.marinas@arm.com, christian.koenig@amd.com, jgg@ziepe.ca, joro@8bytes.org, m.szyprowski@samsung.com, robin.murphy@arm.com, steven.price@arm.com, sumit.semwal@linaro.org, suzuki.poulose@arm.com, tglx@kernel.org, will@kernel.org, linux@armlinux.org.uk, benjamin.gaignard@collabora.com, Brian.Starkey@arm.com, jstultz@google.com, mark.rutland@arm.com, radu@rendec.net, tjmercier@google.com, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, kas@kernel.org, rick.p.edgecombe@intel.com, kys@microsoft. com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com, pbonzini@redhat.com, vkuznets@redhat.com, luto@kernel.org, peterz@infradead.org, dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, linaro-mm-sig@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, patches@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 Wed, 04 Nov 2026 16:45:55 +0000, "Aneesh Kumar K.V (Arm)" wrote: > > VPE L1 tables are allocated from the CPU-starting callback, where sleeping is > not allowed. Remove the page allocation from this atomic path. > > Use a blocking allocation for the boot CPU and record the resulting table > order. Allocate a page of that order from the sleepable CPU hotplug prepare > stage for each secondary CPU. Consume the preallocated page only when the CPU > cannot inherit an existing redistributor or ITS table. > > Reclaim unused preallocations after the CPU reaches the online state, and from > the prepare-state teardown when CPU bring-up aborts. No. The way to do it is to move the ITS probing out of the non-sleepable CPU hotplug path. I proposed a potential hack at [1] (which I find far more palatable than this proposal), but the real fix is to probe the ITSs as devices. Putting even more ugly hacks on top of the existing PoS driver is definitely not an acceptable outcome. M. [1] https://lore.kernel.org/all/86tswrkrh4.wl-maz@kernel.org/ -- Without deviation from the norm, progress is not possible.