From patchwork Fri Jan 6 08:56:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Xin3" X-Patchwork-Id: 13091177 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 DAEE7C5479D for ; Fri, 6 Jan 2023 09:21:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232631AbjAFJVm (ORCPT ); Fri, 6 Jan 2023 04:21:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233071AbjAFJUY (ORCPT ); Fri, 6 Jan 2023 04:20:24 -0500 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A6F96B5DC; Fri, 6 Jan 2023 01:20:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672996823; x=1704532823; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=vMwbqYEWnUbvFLrH3fG7++T8RQchYd07LmgiIGfo4YE=; b=jF1MX+gYmVNyLApAQmUVrPm7y0L1wggan17PytCBdIcIPQo57iUYvZyl rtJDNW6JGiIw5+BHA2ktwQyPyLYXceIFZ3zpOei48ZJJUhPSbjSFVtgk/ jjEPVZrrC+rQdescRjfoWw5q/gTlR25OZQg8V0DZBy10R9GiON3rOwW07 TTkuEalvzMLxcZf8qXM5Ree75dIUwZYbQRnz2qEPV/oiyPRksjTFHaOOm tmVvmlkQnuCZ4y3ymnJvaObPbVIEtA1gJmh8UYyKbq2PPTK+N40TMr317 YbMyUqqnCk4JkEGvCIl4EFQp2NQ5inf60GfHSqLTRsP3dz4DWNMwQhto/ g==; X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="322511582" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="322511582" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jan 2023 01:20:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10581"; a="719139430" X-IronPort-AV: E=Sophos;i="5.96,304,1665471600"; d="scan'208";a="719139430" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga008.fm.intel.com with ESMTP; 06 Jan 2023 01:20:16 -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: [RFC PATCH v2 23/32] x86/fred: update MSR_IA32_FRED_RSP0 during task switch Date: Fri, 6 Jan 2023 00:56:08 -0800 Message-Id: <20230106085617.17248-24-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230106085617.17248-1-xin3.li@intel.com> References: <20230106085617.17248-1-xin3.li@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: "H. Peter Anvin (Intel)" MSR_IA32_FRED_RSP0 is used during ring 3 event delivery, and needs to be updated to point to the top of next task stack during task switch. Update MSR_IA32_FRED_RSP0 with WRMSR instruction for now, and will use WRMSRNS/WRMSRLIST for performance once it gets upstreamed. Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Xin Li --- arch/x86/include/asm/switch_to.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h index c08eb0fdd11f..499c6a701558 100644 --- a/arch/x86/include/asm/switch_to.h +++ b/arch/x86/include/asm/switch_to.h @@ -71,9 +71,16 @@ static inline void update_task_stack(struct task_struct *task) else this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0); #else - /* Xen PV enters the kernel on the thread stack. */ - if (static_cpu_has(X86_FEATURE_XENPV)) + if (cpu_feature_enabled(X86_FEATURE_FRED)) { + /* + * Will use WRMSRNS/WRMSRLIST for performance once it's upstreamed. + */ + wrmsrl(MSR_IA32_FRED_RSP0, + task_top_of_stack(task) + TOP_OF_KERNEL_STACK_PADDING); + } else if (static_cpu_has(X86_FEATURE_XENPV)) { + /* Xen PV enters the kernel on the thread stack. */ load_sp0(task_top_of_stack(task)); + } #endif }