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 03DE2EDB7D4 for ; Tue, 7 Apr 2026 09:32:22 +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=jzYf1Hv2JmuH8VIiQtUJrr8SNTqHqZ6SpcJMeA9CfZQ=; b=BJzrc1Xj7G8IwGBhXL2iUeUR/2 zCi69+AEL9XDks/5LWg3F+UQk6OCIB+cPaDQAeQQo/yQJ2rN6uVgupSVRV8mtAZJuLKKEYSiKTULQ fuDs+mcDFfrov996UiNEDOQmbk8uhQeAyAm6hLLAHECEm2TZ4qogTxxvA5TQqHUdq7waRROm3aYWs dsV9Aeq6B0XBcOCGk2z/rF8fWA7r5ie2A2y40xmlUfdTDHoTwBLxDf1edBAEUyx/bnMwmk7jMO5Bc m1IanTRmoFylPxpIkFU7Pp/DidnHqT8bqafYDd24Z8GyXirPLohwx28u+cAPD7j+p/RU27WSKbb1B fbsfQyOQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wA2nA-00000006E52-17Gl; Tue, 07 Apr 2026 09:32:16 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wA2n7-00000006E4c-3INm for linux-arm-kernel@lists.infradead.org; Tue, 07 Apr 2026 09:32:15 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 74C121A00; Tue, 7 Apr 2026 02:32:04 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8770B3F7D8; Tue, 7 Apr 2026 02:32:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1775554330; bh=bghqVgVi2rFpebPFdJZ8KlldKSei03ZbC3RuMA7fBIQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NhWYcbEhkFfiMRGOXn92UL+3h4avxJGszc0GnCTCQst0YLBovrcfCb2id6UFMHVgq lNnUC1uqwmd74JeQbK0LBmuCFiIYw/dECq6d/pDT8ZmGmNiVDaNDy6eOI8/ZkgUczG Zz1hOhxPL9x+aJNcEQBXD2WbAyOcplVVWlsipxo8= Date: Tue, 7 Apr 2026 10:32:06 +0100 From: Catalin Marinas To: Ryan Roberts Cc: Will Deacon , "David Hildenbrand (Arm)" , Dev Jain , Yang Shi , Suzuki K Poulose , Jinjiang Tu , Kevin Brodsky , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests Message-ID: References: <20260330161705.3349825-1-ryan.roberts@arm.com> <20260330161705.3349825-2-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260407_023213_884388_35E864DE X-CRM114-Status: GOOD ( 23.39 ) 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 Tue, Apr 07, 2026 at 09:43:42AM +0100, Ryan Roberts wrote: > On 03/04/2026 11:31, Catalin Marinas wrote: > > On Thu, Apr 02, 2026 at 09:43:59PM +0100, Catalin Marinas wrote: > >> Another thing I couldn't get my head around - IIUC is_realm_world() > >> won't return true for map_mem() yet (if in a realm). Can we have realms > >> on hardware that does not support BBML2_NOABORT? We may not have > >> configuration with rodata_full set (it should be complementary to realm > >> support). > > > > With rodata_full==false, can_set_direct_map() returns false initially > > but after arm64_rsi_init() it starts returning true if is_realm_world(). > > The side-effect is that map_mem() goes for block mappings and > > linear_map_requires_bbml2 set to false. Later on, > > linear_map_maybe_split_to_ptes() will skip the splitting. > > > > Unless I'm missing something, is_realm_world() calls in > > force_pte_mapping() and can_set_direct_map() are useless. I'd remove > > them and either require BBML2_NOABORT with CCA or get the user to force > > rodata_full when running in realms. Or move arm64_rsi_init() even > > earlier? > > I'd need Suzuki to comment on this. As I said in the other mail, I was treating > this like a pre-existing bug. But I guess linear_map_requires_bbml2 ending up > wrong is a problem here. I'm not sure it's quite as simple as requiring > BBML2_NOABORT with CCA as we still need can_set_direct_map() to return true if > we are in a realm. can_set_direct_map() == true is not a property of the realm but rather a requirement. In the absence of BBML2_NOABORT, I guess the test was added under the assumption that force_pte_mapping() also returns true if is_realm_world(). We might as well add a variable or static label to track whether can_set_direct_map() is possible and avoid tests that duplicate force_pte_mapping(). This won't solve the is_realm_world() changing polarity during boot but at least we know it won't suddenly make can_set_direct_map() return true when it shouldn't. -- Catalin