From patchwork Fri Mar 12 23:16:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Stabellini X-Patchwork-Id: 12136151 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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 427E0C433E0 for ; Fri, 12 Mar 2021 23:17:04 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 DE16A64F86 for ; Fri, 12 Mar 2021 23:17:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE16A64F86 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.97373.184966 (Exim 4.92) (envelope-from ) id 1lKr1J-0005Sk-7S; Fri, 12 Mar 2021 23:16:37 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 97373.184966; Fri, 12 Mar 2021 23:16:37 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKr1J-0005Sd-4X; Fri, 12 Mar 2021 23:16:37 +0000 Received: by outflank-mailman (input) for mailman id 97373; Fri, 12 Mar 2021 23:16:35 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKr1H-0005SY-J8 for xen-devel@lists.xenproject.org; Fri, 12 Mar 2021 23:16:35 +0000 Received: from mail.kernel.org (unknown [198.145.29.99]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id f70687f7-4f32-4561-ae7e-c52a91103163; Fri, 12 Mar 2021 23:16:34 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 9901A64F86; Fri, 12 Mar 2021 23:16:33 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f70687f7-4f32-4561-ae7e-c52a91103163 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615590993; bh=2Ud3Qj5FwQDV8Jl/uhEGUftQWNZdzTuPESSr+hKjGYI=; h=From:To:Cc:Subject:Date:From; b=QwD0MpvCpMLvE+5s33MuW+bGLiuMc0/hr3ZsQn1uqtcjsUQ6oYpdKfWN1qPxCm7bv BuPhXuN3ifD7A95nBw0F4FhePBQk36nD0Ia4Ea5dqfX4nPFtCJoJnxaEErJ06U2+M6 kZzoCfK9Xg2M8Gaz6QBQub+yb6Qs5N7F82KQy8BPmXRbRk3v3ZNxprM1W5/skNRT7p WCIf0axZ4x7GbVYDLTijjvWbhsYgTNhoDZIgwcoTRZ8qQq6ITc/uIDusYyYCK9RELk dIdXqkUncwyE07E8GioAhh+dmion+BXF8u2Fjkaf3m/O+IYMfOsN1z7QKMucGe27ME 03DW5/3TwB0nA== From: Stefano Stabellini To: xen-devel@lists.xenproject.org Cc: sstabellini@kernel.org, jbeulich@suse.com, andrew.cooper3@citrix.com, julien@xen.org, Bertrand.Marquis@arm.com, Stefano Stabellini Subject: [PATCH v3] xen: introduce XENFEAT_direct_mapped and XENFEAT_not_direct_mapped Date: Fri, 12 Mar 2021 15:16:32 -0800 Message-Id: <20210312231632.5666-1-sstabellini@kernel.org> X-Mailer: git-send-email 2.17.1 Introduce two feature flags to tell the domain whether it is direct-mapped or not. It allows the guest kernel to make informed decisions on things such as swiotlb-xen enablement. The introduction of both flags (XENFEAT_direct_mapped and XENFEAT_not_direct_mapped) allows the guest kernel to avoid any guesswork if one of the two is present, or fallback to the current checks if neither of them is present. XENFEAT_direct_mapped is always set for not auto-translated guests. For auto-translated guests, only Dom0 on ARM is direct-mapped. Also, see is_domain_direct_mapped() which refers to auto-translated guests: xen/include/asm-arm/domain.h:is_domain_direct_mapped xen/include/asm-x86/domain.h:is_domain_direct_mapped Signed-off-by: Stefano Stabellini CC: jbeulich@suse.com CC: andrew.cooper3@citrix.com CC: julien@xen.org Reviewed-by: Julien Grall --- Changes in v3: - swap 2 conditions of || - improve in-code comment to cover existing assumptions Changes in v2: - code style improvements - better comments - better commit message - not auto_translated domains are direct_mapped --- xen/common/kernel.c | 4 ++++ xen/include/public/features.h | 14 ++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/xen/common/kernel.c b/xen/common/kernel.c index 7a345ae45e..d77756a81e 100644 --- a/xen/common/kernel.c +++ b/xen/common/kernel.c @@ -560,6 +560,10 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg) (1U << XENFEAT_hvm_callback_vector) | (has_pirq(d) ? (1U << XENFEAT_hvm_pirqs) : 0); #endif + if ( !paging_mode_translate(d) || is_domain_direct_mapped(d) ) + fi.submap |= (1U << XENFEAT_direct_mapped); + else + fi.submap |= (1U << XENFEAT_not_direct_mapped); break; default: return -EINVAL; diff --git a/xen/include/public/features.h b/xen/include/public/features.h index 1613b2aab8..9ee2f760ef 100644 --- a/xen/include/public/features.h +++ b/xen/include/public/features.h @@ -114,6 +114,20 @@ */ #define XENFEAT_linux_rsdp_unrestricted 15 +/* + * A direct-mapped (or 1:1 mapped) domain is a domain for which its + * local pages have gfn == mfn. If a domain is direct-mapped, + * XENFEAT_direct_mapped is set; otherwise XENFEAT_not_direct_mapped + * is set. + * + * If neither flag is set (e.g. older Xen releases) the assumptions are: + * - not auto_translated domains (x86 only) are always direct-mapped + * - on x86, auto_translated domains are not direct-mapped + * - on ARM, Dom0 is direct-mapped, DomUs are not + */ +#define XENFEAT_not_direct_mapped 16 +#define XENFEAT_direct_mapped 17 + #define XENFEAT_NR_SUBMAPS 1 #endif /* __XEN_PUBLIC_FEATURES_H__ */