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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D86B6CFD2F6 for ; Thu, 27 Nov 2025 17:29:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3057E6B0093; Thu, 27 Nov 2025 12:29:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B53E6B0095; Thu, 27 Nov 2025 12:29:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 092B26B0098; Thu, 27 Nov 2025 12:29:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id E73476B0093 for ; Thu, 27 Nov 2025 12:29:45 -0500 (EST) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id AE7D1140218 for ; Thu, 27 Nov 2025 17:29:45 +0000 (UTC) X-FDA: 84157074330.17.46FC1FB Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf21.hostedemail.com (Postfix) with ESMTP id B4EBF1C000A for ; Thu, 27 Nov 2025 17:29:43 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=M5DsguCG; spf=pass (imf21.hostedemail.com: domain of kas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1764264583; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=bGPkY5GyhjBNFnVPgzjBj/fJDLdTy8lOV4FUFCeETQA=; b=nO19cBRjGv56wAyoqvRLLfSPRBkWOmUWOl25+VNfxIo5NvXrntKk3QK7nAbHsPwUt6jLh2 37dhaNsvXlt1PgvDc14Y87jP1JNa+HMdPhvD6ak22boj4BFNTUjow8AqdZNlR33e34G2sL jbbG+gncn2gOwNjK/aH2KXGLB3J1kEI= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1764264583; a=rsa-sha256; cv=none; b=SFq1ANMsLZbk67QWrIbsQ3loo+mTnJRyGOYyLDxaPxrLWv5n0lr7LfgG+vcCYQYpF/h4mh L6qzT/VnpsoZuvE4mLDry1j+qiu7qSyTYTPoqOTjuSI+hjWxKShSnJ9Lt8hIeNTvX/tbSu 1UpnBQ8dmD/MtxjQNdxfRRMefIjpmgk= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=M5DsguCG; spf=pass (imf21.hostedemail.com: domain of kas@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=kas@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 0E12760242; Thu, 27 Nov 2025 17:29:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43863C4AF09; Thu, 27 Nov 2025 17:29:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764264582; bh=nB4fj1qSwqt+nXUD6T8fItX7qNQnaNO9Nn1wmWp2EB4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M5DsguCGSx6lJRFcfXOOkiUMxXVeq2+FKS9DGpaSe+2ii8+ftz3gDSYEY0LXNJ+p7 uFlLnNB641IAaAHPyX0RoWoJIbHvIxMeQJOm+epTUxeE6bCNO/5OuREbRugrrT7GmI jgEVv7ylwxJj9eNzp3pGABTQYUFRzwmLEZeUR+EcGH0cFxiiAzpryuewilZiJo0dBx NQwPRpb7fMu1X4Zmiu+sQGVi1IOHMauD3BIYnOUPOUwTAdzKJlwUY6S2eADsXgdAPD NSK94NVaxinaCaZapap2Q/beSQI6/cJak04qaKRuPfRbA7t4RWeBqJYu60t88nUJLj mxBt0ow+zwILQ== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.phl.internal (Postfix) with ESMTP id 63FBAF40073; Thu, 27 Nov 2025 12:29:41 -0500 (EST) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-02.internal (MEProxy); Thu, 27 Nov 2025 12:29:41 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdeggddvgeejkedvucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtsfdttddtvdenucfhrhhomhepmfhirhihlhcu ufhhuhhtshgvmhgruhcuoehkrghssehkvghrnhgvlhdrohhrgheqnecuggftrfgrthhtvg hrnhepheeikeeuveduheevtddvffekhfeufefhvedtudehheektdfhtdehjeevleeuffeg necuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepkhhirh hilhhlodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdduieduudeivdeiheeh qddvkeeggeegjedvkedqkhgrsheppehkvghrnhgvlhdrohhrghesshhhuhhtvghmohhvrd hnrghmvgdpnhgspghrtghpthhtohepfedvpdhmohguvgepshhmthhpohhuthdprhgtphht thhopehprhhsrghmphgrthesrghmugdrtghomhdprhgtphhtthhopehlihhnuhigqdhmmh eskhhvrggtkhdrohhrghdprhgtphhtthhopehlihhnuhigqdgtohgtoheslhhishhtshdr lhhinhhugidruggvvhdprhgtphhtthhopehlihhnuhigqdgvfhhisehvghgvrhdrkhgvrh hnvghlrdhorhhgpdhrtghpthhtohepgiekieeskhgvrhhnvghlrdhorhhgpdhrtghpthht oheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpth htohepthhglhigsehlihhnuhhtrhhonhhigidruggvpdhrtghpthhtohepmhhinhhgohes rhgvughhrghtrdgtohhmpdhrtghpthhtohepsghpsegrlhhivghnkedruggv X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 27 Nov 2025 12:29:40 -0500 (EST) Date: Thu, 27 Nov 2025 17:29:39 +0000 From: Kiryl Shutsemau To: "Pratik R. Sampat" Cc: linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, ardb@kernel.org, akpm@linux-foundation.org, david@redhat.com, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com Subject: Re: [RFC PATCH 1/4] efi/libstub: Decouple memory bitmap from the unaccepted table Message-ID: References: <20251125175753.1428857-1-prsampat@amd.com> <20251125175753.1428857-2-prsampat@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: B4EBF1C000A X-Rspamd-Server: rspam06 X-Rspam-User: X-Stat-Signature: p4zx1jkkb3d6eccgwn6wkwayk4c9b1xg X-HE-Tag: 1764264583-924595 X-HE-Meta: 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 QmmWE96M 1RUBJuQBkMNpXe+1Y1gq4Kl1gVbIU5WuK/P6RWvnbIXf6zMtiXPclbYid7KncRcFoUxlPuZR4Xj+ELtp2suolqxFithIyoRUsHxFbzlx3pOT+yETpPOm2qO9h1VoP45B2ssknk/7k/dxXap7+OJwng6SK5TabACkXaTBcNcdTTZYLrOoslovKHKohYrIYndgNd6n6qGloD3jZh7qocVlEMGdiUSLr/TvGYGLKD0xk9agnVCOGIl+8e1WTezO1yM6oUdJsgCcekXlf3tQgYcdBP8Gl2A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Nov 26, 2025 at 04:27:19PM -0600, Pratik R. Sampat wrote: > Hi Kiryl, > > Thanks for you comments. > > On 11/26/25 5:08 AM, Kiryl Shutsemau wrote: > > On Tue, Nov 25, 2025 at 11:57:50AM -0600, Pratik R. Sampat wrote: > >> Memory hotplug in secure environments requires the unaccepted memory > >> bitmap to grow as new memory is added. Currently, the bitmap is > >> implemented as a flexible array member at the end of struct > >> efi_unaccepted_memory, which is reserved by memblock at boot and cannot > >> be resized without reallocating the entire structure. > >> > >> Replace the flexible array member with a pointer. > > > > Well, it break interoperability between kernel before and after the > > patch. Consider kexec from kernel without the patch to the kernel with > > the patch and then back to older kernel. It is ABI break. > > > > Is re-allocating the entire structure such a big pain? > > > > We could do that. My concern is that we would then need to protect the > entire table instead of just the bitmap, which may add an additional > overhead? What additional overhead? The main contention is going to be on binmap anyway. -- Kiryl Shutsemau / Kirill A. Shutemov