From patchwork Thu Sep 14 04:48:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13384567 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 5498DEDE980 for ; Thu, 14 Sep 2023 05:33:35 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.601922.938288 (Exim 4.92) (envelope-from ) id 1qgeyn-00079K-On; Thu, 14 Sep 2023 05:33:29 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 601922.938288; Thu, 14 Sep 2023 05:33:29 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qgeyn-00079B-LA; Thu, 14 Sep 2023 05:33:29 +0000 Received: by outflank-mailman (input) for mailman id 601922; Thu, 14 Sep 2023 05:33:28 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qgelT-0001XI-2f for xen-devel@lists.xenproject.org; Thu, 14 Sep 2023 05:19:43 +0000 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 4db2f59c-52be-11ee-9b0d-b553b5be7939; Thu, 14 Sep 2023 07:19:39 +0200 (CEST) Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 22:17:48 -0700 Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga001.jf.intel.com with ESMTP; 13 Sep 2023 22:17:47 -0700 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: 4db2f59c-52be-11ee-9b0d-b553b5be7939 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694668780; x=1726204780; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DfU6e7Lxi3caIgHaas3RwgcYA9izTEYulGU0upU0hWQ=; b=C2qSgSliymajvEnf/caBa0OMsph2kLxROcw2fpnHpdbIeXh1YLgG6gvc JFZKVBUXx+5neaXw/Nl+HS9iqsNLYFHP5E56NwhAiZwRQguabQ60XgEB4 iUlSLIbPZrU74Mp8O/ltxGGviX7WlMQGSSHXwHPXyXyPp/BYgBs+7zJAL dsVkh2SThVsspdP/UJ3YHfLPgFtg/HWIk4XF+jWMMqkj3fiL39Z3i2Rvm h0nR9Dygy1ElvA8RHkFMldYhZvgdj9Z0jmyATSXuLK0oDW4uPJng5PuE6 f1no63Z4sCBxwfcBbNlOz0CP9Ca0lB86uFUVmRBvCiyHCj7v4F/B+d/6z A==; X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="382661536" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="382661536" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="779488847" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="779488847" 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: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org, andrew.cooper3@citrix.com, jiangshanlai@gmail.com Subject: [PATCH v10 36/38] x86/fred: Add fred_syscall_init() Date: Wed, 13 Sep 2023 21:48:03 -0700 Message-Id: <20230914044805.301390-37-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230914044805.301390-1-xin3.li@intel.com> References: <20230914044805.301390-1-xin3.li@intel.com> MIME-Version: 1.0 From: "H. Peter Anvin (Intel)" Add a syscall initialization function fred_syscall_init() for FRED, and this is really just to skip setting up SYSCALL/SYSENTER related MSRs, e.g., MSR_LSTAR and invalidate SYSENTER configurations, because FRED uses the ring 3 FRED entrypoint for SYSCALL and SYSENTER, and ERETU is the only legit instruction to return to ring 3 per FRED spec 5.0. Signed-off-by: H. Peter Anvin (Intel) Tested-by: Shan Kang Signed-off-by: Xin Li --- arch/x86/kernel/cpu/common.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index d960b7276008..4cb36e241c9a 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2105,6 +2105,23 @@ static inline void idt_syscall_init(void) X86_EFLAGS_AC|X86_EFLAGS_ID); } +static inline void fred_syscall_init(void) +{ + /* + * Per FRED spec 5.0, FRED uses the ring 3 FRED entrypoint for SYSCALL + * and SYSENTER, and ERETU is the only legit instruction to return to + * ring 3, as a result there is _no_ need to setup the SYSCALL and + * SYSENTER MSRs. + * + * Note, both sysexit and sysret cause #UD when FRED is enabled. + */ + wrmsrl(MSR_LSTAR, 0ULL); + wrmsrl_cstar(0ULL); + wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)GDT_ENTRY_INVALID_SEG); + wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL); + wrmsrl_safe(MSR_IA32_SYSENTER_EIP, 0ULL); +} + /* May not be marked __init: used by software suspend */ void syscall_init(void) {