From patchwork Mon Jul 31 06:32:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13333734 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 5391FC001DC for ; Mon, 31 Jul 2023 07:03:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231196AbjGaHDd (ORCPT ); Mon, 31 Jul 2023 03:03:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231135AbjGaHDX (ORCPT ); Mon, 31 Jul 2023 03:03:23 -0400 Received: from mgamail.intel.com (unknown [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EF1DE7B; Mon, 31 Jul 2023 00:02:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1690786937; x=1722322937; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=sycVsd87zmfA3yJCdcgOgrxd4mm6nSq5VT1UdIRGngQ=; b=Sb11QzFc6ceq0l6D2+ruUClNO8ujAszWBJDj6SztcYOU1DfsTYSJv42N okTd5WK5y1TjFX3HdMy4gJ0pvccjcIuK4WXCl5uvbKFMaos440Jq9SGLI AdkwaP3FXrq2DhhHYUQNfgE0GYyBsvl3XnFUeP3KWtbXppxLQApZguX0T v7hAcwpjwjwndNX6kVO1qYkmARBsrdmABgb4rD1bk7TvhNDznKBI0zler hxTSo91zpuelReQhxkAJMLFrmOabj2QQ1YirIZgSQ+jowleKi5L8gPKsz 0yOQLD+OyLNzzHxNXXbQvfpxbir9n6oaMNFFTN/5rPWSM0p423iALYeaz A==; X-IronPort-AV: E=McAfee;i="6600,9927,10787"; a="371649068" X-IronPort-AV: E=Sophos;i="6.01,244,1684825200"; d="scan'208";a="371649068" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2023 00:02:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.01,202,1684825200"; d="scan'208";a="871543425" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga001.fm.intel.com with ESMTP; 31 Jul 2023 00:02:04 -0700 From: Xin Li To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Andy Lutomirski , Oleg Nesterov , Tony Luck , "K . Y . Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Sean Christopherson , Peter Zijlstra , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Josh Poimboeuf , "Paul E . McKenney" , Catalin Marinas , Randy Dunlap , Steven Rostedt , Kim Phillips , Xin Li , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Liam R . Howlett" , Sebastian Reichel , "Kirill A . Shutemov" , Suren Baghdasaryan , Pawan Gupta , Jiaxi Chen , Babu Moger , Jim Mattson , Sandipan Das , Lai Jiangshan , Hans de Goede , Reinette Chatre , Daniel Sneddon , Breno Leitao , Nikunj A Dadhania , Brian Gerst , Sami Tolvanen , Alexander Potapenko , Andrew Morton , Arnd Bergmann , "Eric W . Biederman" , Kees Cook , Masami Hiramatsu , Masahiro Yamada , Ze Gao , Fei Li , Conghui , Ashok Raj , "Jason A . Donenfeld" , Mark Rutland , Jacob Pan , Jiapeng Chong , Jane Malalane , David Woodhouse , Boris Ostrovsky , Arnaldo Carvalho de Melo , Yantengsi , Christophe Leroy , Sathvika Vasireddy Subject: [PATCH v9 14/36] x86/fred: Disallow the swapgs instruction when FRED is enabled Date: Sun, 30 Jul 2023 23:32:55 -0700 Message-Id: <20230731063317.3720-15-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230731063317.3720-1-xin3.li@intel.com> References: <20230731063317.3720-1-xin3.li@intel.com> MIME-Version: 1.0 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 from ring 3 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. 3) LKGS is already upstreamed and automatically enabled with FRED to load the GS base address directly into the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s descriptor cache. As a result, there is no need to SWAPGS away from the kernel GS base, i.e., the swapgs instruction is no longer needed when FRED is enabled, thus is disallowed. Otherwise it causes #UD. Signed-off-by: H. Peter Anvin (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- Changes since v8: * Explain why writing directly to the IA32_KERNEL_GS_BASE MSR is doing the right thing (Thomas Gleixner). --- 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 265ab8fcb146..6d5fed29f552 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -166,7 +166,8 @@ 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(); @@ -191,7 +192,8 @@ 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();