From nobody Sun Feb 8 23:25:24 2026 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 59A26C7619A for ; Mon, 27 Mar 2023 08:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233317AbjC0I0F (ORCPT ); Mon, 27 Mar 2023 04:26:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233120AbjC0IYz (ORCPT ); Mon, 27 Mar 2023 04:24:55 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 317E2559F; Mon, 27 Mar 2023 01:24:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1679905479; x=1711441479; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SfNRJW38HST/J2vYBy+d2Rz7YNwfS+VaJzsap6qMLmE=; b=fvgsSzQg2y5+8N4JOrf6ltJVVeIToOnneOUJoxpYYCCUW5KZkhkG9Ocb K7ehhSjB6sbKJqxXc3ZicSKnM4AL9q4QJzgnXMN/DKGZFJULH14eaJqA7 cBDoxuxTgizgE0ywkJJXIMj5494rMjDnshr/E5x14nMgIgeKCMCkQeT1z Y+JZtpPfzNO1v5zYCjHw5SpUrBb3lEHSXWRha0+VEZnqpiRsXGV6/xp8F nECDULAFymj8ZqOn/GW9UXGZNZuwIY1c8UMf5DBX3y3kYH6dMOgIzw6aG vjlzfmtWk4PXfjh3k6lm4VEWzgbc9eU9H2D728oJQ8xjnwr0buOOEO906 A==; X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="338930315" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="338930315" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2023 01:24:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10661"; a="713787115" X-IronPort-AV: E=Sophos;i="5.98,294,1673942400"; d="scan'208";a="713787115" Received: from unknown (HELO fred..) ([172.25.112.68]) by orsmga008.jf.intel.com with ESMTP; 27 Mar 2023 01:24:37 -0700 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, jiangshanlai@gmail.com, shan.kang@intel.com Subject: [PATCH v6 22/33] x86/fred: update MSR_IA32_FRED_RSP0 during task switch Date: Mon, 27 Mar 2023 00:58:27 -0700 Message-Id: <20230327075838.5403-23-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230327075838.5403-1-xin3.li@intel.com> References: <20230327075838.5403-1-xin3.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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) Tested-by: Shan Kang 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 5c91305d09d2..00fd85abc1d2 100644 --- a/arch/x86/include/asm/switch_to.h +++ b/arch/x86/include/asm/switch_to.h @@ -68,9 +68,16 @@ static inline void update_task_stack(struct task_struct = *task) #ifdef CONFIG_X86_32 this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0); #else - /* Xen PV enters the kernel on the thread stack. */ - if (cpu_feature_enabled(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 (cpu_feature_enabled(X86_FEATURE_XENPV)) { + /* Xen PV enters the kernel on the thread stack. */ load_sp0(task_top_of_stack(task)); + } #endif } =20 --=20 2.34.1