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 582A3C021B8 for ; Thu, 27 Feb 2025 01:38:20 +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=wSv+cwsFRwVh/8elVXcAColPKBd5X2nwPYiupPML4Bc=; b=GuNpp7raCjd6QR0038XaMTqZss hD/8TDAlE2pDjG7nbsjRTWGWPAjoBkbA0gQszPwFu6c2AqHbZNHQn33wJ5Bv4dpPTFpG256pDL2wt hKgpBJEeOw1K+mhZhxvKGxNBAbenEBpli6qLk7UNIJORk6x+HTETCG6kCNlPcQElUrcoX/08Ix/dW If0tbuA5DpbTz+Pvn1ZAm0zBQi6RGw0b0SL+ACR9o8nYxfHDEZ+IwLQjy86zIZC9btosPKjbWN2AG ZwBqVyjffRD23xdjysGb3qdZMf+0/Mh5ohq9QLcoNrj9G6czDLggdUbUHPqrZkh3S2Ed/oO5vIOpS v/DwOXpQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tnSqn-00000005xYw-2MZZ; Thu, 27 Feb 2025 01:38:09 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tnRgh-00000005oBp-2WcL for linux-arm-kernel@lists.infradead.org; Thu, 27 Feb 2025 00:23:41 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id D00835C75C4; Thu, 27 Feb 2025 00:22:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD563C4CED6; Thu, 27 Feb 2025 00:23:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740615818; bh=arZMEBXiCeOAemtlaMD2whA3gu7IqKG3QKa02itcVOg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=r2xqihsoUtx0mnh8RLLIjEAjPgloTP001LONjPAwoV/xeiJy8u+h01ej7a1b68K+7 jUWOnoHeJxZDumCmTj/ZzoZaZG9ydutU8FnLZBzWkpQMicwuNBvJXS2zrYCAs4X0PK 9kteFfAcP9iTwJz0s6ulQ9jOb9Lt2ihSF97X8Vw3k+vC3npgDNha5RcKi1axciDgWl bQ11PamfREIi44x+J2k4VjfstgeKYqFPYJi2np1bifjKJWgWJtGvY9/9IF2ysvlNd/ vbi3gA4SceTDZaht2tDFNVSpwr3sVxPgE21Im3ifhTnJ3VD2AkKkqxicmsGA5ts9Yd gDhpiL5fqcsDw== Date: Thu, 27 Feb 2025 00:23:31 +0000 From: Will Deacon To: Catalin Marinas Cc: Steven Price , "Aneesh Kumar K . V" , Suzuki K Poulose , Marc Zyngier , James Morse , Oliver Upton , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , kvmarm@lists.linux.dev, kvm@vger.kernel.org Subject: Re: [PATCH v7 09/11] arm64: Enable memory encrypt for Realms Message-ID: <20250227002330.GA24899@willie-the-truck> References: <20241017131434.40935-1-steven.price@arm.com> <20241017131434.40935-10-steven.price@arm.com> <5aeb6f47-12be-40d5-be6f-847bb8ddc605@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250226_162339_726262_D4583FA7 X-CRM114-Status: GOOD ( 24.30 ) 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 Wed, Feb 26, 2025 at 07:03:01PM +0000, Catalin Marinas wrote: > On Wed, Feb 19, 2025 at 02:30:28PM +0000, Steven Price wrote: > > > @@ -23,14 +25,16 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED > > > bool can_set_direct_map(void) > > > { > > > /* > > > - * rodata_full and DEBUG_PAGEALLOC require linear map to be > > > - * mapped at page granularity, so that it is possible to > > > + * rodata_full, DEBUG_PAGEALLOC and a Realm guest all require linear > > > + * map to be mapped at page granularity, so that it is possible to > > > * protect/unprotect single pages. > > > * > > > * KFENCE pool requires page-granular mapping if initialized late. > > > + * > > > + * Realms need to make pages shared/protected at page granularity. > > > */ > > > return rodata_full || debug_pagealloc_enabled() || > > > - arm64_kfence_can_set_direct_map(); > > > + arm64_kfence_can_set_direct_map() || is_realm_world(); > > > } > > > > Aneesh pointed out that this call to is_realm_world() is now too early > > since the decision to delay the RSI detection. The upshot is that a > > realm guest which doesn't have page granularity forced for other reasons > > will fail to share pages with the host. > > > > At the moment I can think of a couple of options: > > > > (1) Make rodata_full a requirement for realm guests. > > CONFIG_RODATA_FULL_DEFAULT_ENABLED is already "default y" so this > > isn't a big ask. > > > > (2) Revisit the idea of detecting when running as a realm guest early. > > This has the advantage of also "fixing" earlycon (no need to > > manually specify the shared-alias of an unprotected UART). > > > > I'm currently leaning towards (1) because it's the default anyway. But > > if we're going to need to fix earlycon (or indeed find other similar > > issues) then (2) would obviously make sense. > > I'd go with (1) since the end result is the same even if we implemented > (2) - i.e. we still avoid block mappings in realms. Is it, though? The config option is about the default behaviour but there's still an "rodata=" option on the command-line. Will