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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DB8BC64EC4 for ; Tue, 7 Mar 2023 03:07:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230320AbjCGDHY (ORCPT ); Mon, 6 Mar 2023 22:07:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230216AbjCGDGl (ORCPT ); Mon, 6 Mar 2023 22:06:41 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEE4D7C9F0; Mon, 6 Mar 2023 19:05:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678158336; x=1709694336; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=JCKu4lASdy4fofKGHW4gy5ePwfNi7YQxHJ13+kwlv3k=; b=hNiJvt5CUHaZqkc2NNqWSVDWOOpAS3RE4qJ3csDtOu+a/RtIoK3BAL0d bCxiaqxPJwkveCoV6cABaOSytOHRNhMVY96mAeDFtpH68GN0mZ+VMbBod XXEI3p4VgTMQUid00FnsOpWJVK8smeodNxX5uoWXkNKSA/Fa92RCU+Tee q1/nJWEy+1tbnmWdpJ9bjuwp8NKyZwSv8pWYrw3Ow/jhywkFgnI7BGquD OYm92CJ02tdL7CDiH8hXlC5O5XWEzR+riJd6M2XEnW3JxvjopomjTWxBw UXOZ4ui9XJ/toqNN3Y/yt7GH2BZGi+0B7GZZwyWpSpGGWaGpdTT7bh1k8 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10641"; a="338072548" X-IronPort-AV: E=Sophos;i="5.98,238,1673942400"; d="scan'208";a="338072548" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2023 19:05:20 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10641"; a="676409897" X-IronPort-AV: E=Sophos;i="5.98,238,1673942400"; d="scan'208";a="676409897" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga002.jf.intel.com with ESMTP; 06 Mar 2023 19:05:20 -0800 From: Xin Li To: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com Subject: [PATCH v5 25/34] x86/fred: disallow the swapgs instruction when FRED is enabled Date: Mon, 6 Mar 2023 18:39:37 -0800 Message-Id: <20230307023946.14516-26-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230307023946.14516-1-xin3.li@intel.com> References: <20230307023946.14516-1-xin3.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: "H. Peter Anvin (Intel)" The FRED architecture establishes the full supervisor/user through: 1) FRED event delivery swaps the value of the GS base address and that of the IA32_KERNEL_GS_BASE MSR. 2) ERETU swaps the value of the GS base address and that of the IA32_KERNEL_GS_BASE MSR. Thus, the swapgs instruction is disallowed when FRED is enabled, otherwise it cauess #UD. Signed-off-by: H. Peter Anvin (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- arch/x86/kernel/process_64.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 57de166dc61c..ff6594dbea4a 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -165,7 +165,8 @@ static noinstr unsigned long __rdgsbase_inactive(void) lockdep_assert_irqs_disabled(); - if (!cpu_feature_enabled(X86_FEATURE_XENPV)) { + if (!cpu_feature_enabled(X86_FEATURE_FRED) && + !cpu_feature_enabled(X86_FEATURE_XENPV)) { native_swapgs(); gsbase = rdgsbase(); native_swapgs(); @@ -190,7 +191,8 @@ static noinstr void __wrgsbase_inactive(unsigned long gsbase) { lockdep_assert_irqs_disabled(); - if (!cpu_feature_enabled(X86_FEATURE_XENPV)) { + if (!cpu_feature_enabled(X86_FEATURE_FRED) && + !cpu_feature_enabled(X86_FEATURE_XENPV)) { native_swapgs(); wrgsbase(gsbase); native_swapgs(); -- 2.34.1