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 X-Spam-Level: X-Spam-Status: No, score=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B9FFC43214 for ; Thu, 26 Aug 2021 12:18:58 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CF4E861052 for ; Thu, 26 Aug 2021 12:18:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CF4E861052 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=QSKVolYmZNZx4YrFjdgZxLZZjJq6+WIXSnriZA1ZmIs=; b=eiorKWx+ketI1b r3Q8+W4e7HE6cOEWeSO5nNWbrZcF0MvZxpI8GOO27iZi/6oSGgef05aq9z8rCEx0ddcY6RnRWUBfQ EgGqR4BvXnhrCFNo8KViDfcWfu2ihe4HrijVJ0EKKMy+TuQzdtAWYmj+Y0iaBF2DsBox7TmOIU0Or S706iv8Pibg/74nvfg1k7lDk/hndGGSDtwXZThpSG6PL7zbH/5sLxcy6JUDGh6Txbjk2zQHpUZpe+ iscDreHVAHBT9FQPHjI/5oP07/qEzOKdCX72nPs0jRJ1KEvhxYJzD38Iuz28FLxJYl8zsrJ8nsEs4 O/pvI68A7sASnc8qozfg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJEJB-00A2UK-Q3; Thu, 26 Aug 2021 12:16:37 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJEJ7-00A2Tt-WC for linux-arm-kernel@lists.infradead.org; Thu, 26 Aug 2021 12:16:35 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 31A6460F45; Thu, 26 Aug 2021 12:16:32 +0000 (UTC) Date: Thu, 26 Aug 2021 13:16:24 +0100 From: Catalin Marinas To: Ard Biesheuvel Cc: Will Deacon , Linux ARM , Mark Rutland , Marc Zyngier , Anshuman Khandual , Steve Capper Subject: Re: [RFC PATCH] arm64: mm: limit linear region to 51 bits for KVM in nVHE mode Message-ID: <20210826121623.GB30910@arm.com> References: <20210810161244.84231-1-ardb@kernel.org> <20210824105920.GB22752@willie-the-truck> MIME-Version: 1.0 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-20210826_051634_103190_8AD9AC7C X-CRM114-Status: GOOD ( 21.83 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Aug 24, 2021 at 02:56:22PM +0200, Ard Biesheuvel wrote: > On Tue, 24 Aug 2021 at 12:59, Will Deacon wrote: > > On Tue, Aug 10, 2021 at 06:12:44PM +0200, Ard Biesheuvel wrote: > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > > index 8490ed2917ff..542dad13e2fc 100644 > > > --- a/arch/arm64/mm/init.c > > > +++ b/arch/arm64/mm/init.c > > > @@ -282,7 +282,21 @@ static void __init fdt_enforce_memory_region(void) > > > > > > void __init arm64_memblock_init(void) > > > { > > > - const s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual); > > > + s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual); > > > + > > > + /* > > > + * Corner case: 52-bit VA capable systems running KVM in nVHE mode may > > > + * be limited in their ability to support a linear map that exceeds 51 > > > + * bits of VA space, depending on the placement of the ID map. Given > > > + * that the placement of the ID map may be randomized, let's simply > > > + * limit the kernel's linear map to 51 bits as well if we detect this > > > + * configuration. > > > + */ > > > + if (IS_ENABLED(CONFIG_KVM) && vabits_actual == 52 && > > > + !is_kernel_in_hyp_mode()) { > > > + pr_info("Capping linear region to 51 bits for KVM in nVHE mode on LVA capable hardware.\n"); > > > + linear_region_size = BIT(51); > > > + } > > > > Slight nit, but to avoid having to think about PAGE_END I think this would > > be a little clearer as: > > > > if (IS_ENABLED(CONFIG_KVM) && !is_kernel_in_hyp_mode()) > > linear_region_size = min_t(u64, linear_region_size, BIT(51)); > > > > Fair enough. Ard, do you plan to post a new version? I can make the change myself locally as well. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel