From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3D8D4C624D0 for ; Wed, 2 Sep 2026 11:22:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=VI+zTa/H4brk4hljsWHx5rnTWZGudrTivFOtubthDSY=; b=igI2LmeuwDoYM2d0CnUPeRbULz LT4An+dFxjcGAI1Z3VgSWPygGc7Lgp7zcI1nVChHx/OmR5REg0UPPFAtcrJ1lCRRY0wIViYgpunKl CjcuQghu+hOD4qTraXU6Idv9grHG8iwqiv8Jz8ngYuA9R9SKeuLK9MoLQqxmqzK6+gkahdFkiwOfc aP3z9gzIcy8yoExijFKVT95SXPSMW4KvPWnFjgPpcAsLC4cf0/GeH2UiyHXxuq9NZKCxsvhGKFoUs 0kPYRUcebtcDlr2eTt79Zi4gY9UPnXYnJ29DXw3XJxg/N3Devn790c90ZM4ozNuQ7gA1i5eAEJWeR qTFXbdKg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1j3F-0000000EUOb-1p7i; Wed, 02 Sep 2026 11:22:45 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x1j3D-0000000EUOP-2NjX for linux-arm-kernel@lists.infradead.org; Wed, 02 Sep 2026 11:22:43 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 5612443D4E; Wed, 2 Sep 2026 11:22:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FEED1F00A3D; Wed, 2 Sep 2026 11:22:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788348163; bh=VI+zTa/H4brk4hljsWHx5rnTWZGudrTivFOtubthDSY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=XUT8yFQFIDAXpJNheMQDAc0u9jQeTZYSg6YEzu3bttwqEFwjfRvwneXYGPOPvT3do 1AHDF3G8NEShvO5v/yxoQTav/PLUJRBdY/qGxocMEvdFe5dDJeR9keggoBS64Q91Wl N5Kpbazegv+XETjnI5S55SxA6pij6Ye8shiUFa0VgJ9SKHXpdyYeYlK5rHcI9X9WX+ TCc4kIk/23CsoMmoQtjuLIMyKa+9djFumuYiKepkDd1PPUgmnTZvSQ8JJOrsqtGYNg Z926LX0rZkRzyFwif0h1ZLRm22R9hD0JPofEKDATAbHh6I2bNhRKOY2xqY5VQTCD/c Puq7EMndNkPGw== Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfauth.ams.internal (Postfix) with ESMTP id 5622A198003A; Wed, 2 Sep 2026 07:22:39 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-05.internal (MEProxy); Wed, 02 Sep 2026 07:22:41 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTFz6itMPqahSEtPkdJJ9WVlua6VjGYOXQgtB6H3nUwkTCAeCZ7daCaLn5zON1t/5A MwWZ4U0HUxKeDH0x08LvUy2Gpht1F9Gi71lOZ5nSHj0qarS92q8yZpXwg0ERpN7IexVqoQ rCXc+94u/RibKKQ9IAsd+X4y4hMuNhJyDmQvT5hKcDPMF120/cUdT4/Tq6AmKcsnk6v++5 /oMEJEwD2wTfPUps0KMjrJxACRV2mqyYw3yu2TEQqOIdZmcFBbdRWzRh0bZZ8Gg7jrLNBY /TrgKqBEcdSeQqKtKM3yTlGC1/LlhFGaVy0VgQb9RdHKxxi/xfP8tbOhqqNspPwC1LnlR4 RG00hbJbFkJixN0Y1uvZGtWRKNW9GgQv0IUgu6Oj3n7otFGxiy5XG76k+BR8k/O5iTYyF/ FwpvXpT5pTGZbkjJlNIncDpg8NyX3LveylVcs+7DDs+LjyVgJVc3vR2rX+orXLmT+GbvLo UB1XA2t094+SPBpEqpc0W3Veap6B3/IUiWyZ/VzXmA7W6UgTdY78NL3S2pjVQh9yv2zF3w y0j/VnrJMFr4g4vKBArfmHHGNrIMnN2ZwIswOcTI1aL8aaWcvaLXiHk3aRV9kK8TY9zKSc 2Tx3FbzLtX8FSrS4lQBH+Qxvy4hUXNh7dUkgEPSxc9dcoig7jpmfVyTyjLNw X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 2 Sep 2026 07:22:38 -0400 (EDT) Date: Wed, 2 Sep 2026 12:22:36 +0100 From: Kiryl Shutsemau To: Nicolin Chen Cc: will@kernel.org, robin.murphy@arm.com, jgg@nvidia.com, joro@8bytes.org, praan@google.com, kevin.tian@intel.com, smostafa@google.com, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, jamien@nvidia.com Subject: Re: [PATCH v10 04/13] iommu/arm-smmu-v3: Disable the EVTQ and the PRIQ in a kdump kernel Message-ID: References: <861f488cbbfa84a4d222a22615adbe5d2617bc87.1788130528.git.nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <861f488cbbfa84a4d222a22615adbe5d2617bc87.1788130528.git.nicolinc@nvidia.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Aug 30, 2026 at 04:18:05PM -0700, Nicolin Chen wrote: > A kdump kernel cannot use either queue. The crashed kernel's CDs and page > tables might be corrupted, so events would spam the EVTQ, and there is no > way to serve the page requests that would arrive at the PRIQ. > > The reset routine still enables both of the queues and then masks the two > enable bits back out, having already programmed the queue bases and taken > the interrupts of both. > > Clear ARM_SMMU_FEAT_EVTQ and ARM_SMMU_FEAT_PRI in the probe instead, so all > of the queue handling, i.e. the interrupts, the IRQ_CTRL bits and the CR0 > enables, keeps away from a kdump kernel via the feature tests. > > Both queues also go unallocated now, as the two allocations test the same > features. Each of them is sized from the maxima that IDR1 advertises, so up > to 4MB apiece on a 4K-page kernel, which a kdump kernel would otherwise pay > for every SMMU instance out of a small crashkernel reservation. > > The IOPF workqueue of the event queue stays allocated here, as untangling > it from the SVA and the stall features takes a pair of changes carried by > the PRI series. It costs a struct and a workqueue rather than the megabytes > that the two queues take, so leave it to that series. > > Suggested-by: Kevin Tian > Suggested-by: Jason Gunthorpe > Suggested-by: Kiryl Shutsemau (Meta) > Suggested-by: Will Deacon > Link: https://lore.kernel.org/all/amiBagGKn-Aym1DK@willie-the-truck/ > Assisted-by: Claude:claude-opus-5 > Signed-off-by: Nicolin Chen Acked-by: Kiryl Shutsemau (Meta) -- Kiryl Shutsemau / Kirill A. Shutemov