From nobody Sat Apr 11 07:07:34 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 3CBDCC678D4 for ; Thu, 2 Mar 2023 05:52:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229911AbjCBFw2 (ORCPT ); Thu, 2 Mar 2023 00:52:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229496AbjCBFvw (ORCPT ); Thu, 2 Mar 2023 00:51:52 -0500 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E1274DE12; Wed, 1 Mar 2023 21:51:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1677736269; x=1709272269; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SfNRJW38HST/J2vYBy+d2Rz7YNwfS+VaJzsap6qMLmE=; b=Zmw+nEZMsh5OaGqBExIrVm8w3i4BOWz5VTMkQzlKk5rrPyEA7quVJvUD dtXVM4An7T+cNlpaVd2P3VavVdrLjrlkWoTQow5wXhagMHsehv3z2WjDr Y4RXvMWQDjPBCaiIyLDl+49sN9vh4eqNo7QYit27CqRIX09G3d2z3bjZs +CCR5Y4H0054iktjAWcRXOHg9Ukuy+x8/KlhHnk3OQaf6UmI4WNjpxVkq pc3+7w3/dKYovaVUaTLMoPCyZDx7LR+xsyMAxhK8wIC1eS4d0KPx0AIhF MzlqcqBhgEVwvEBSIsrPCIDzPQjlR8kpyw4jM+q9FkOFoqt7SE9d4t6v2 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="420887232" X-IronPort-AV: E=Sophos;i="5.98,226,1673942400"; d="scan'208";a="420887232" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Mar 2023 21:50:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10636"; a="920530951" X-IronPort-AV: E=Sophos;i="5.98,226,1673942400"; d="scan'208";a="920530951" Received: from unknown (HELO fred..) ([172.25.112.68]) by fmsmga006.fm.intel.com with ESMTP; 01 Mar 2023 21:50:49 -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 v4 23/34] x86/fred: update MSR_IA32_FRED_RSP0 during task switch Date: Wed, 1 Mar 2023 21:25:00 -0800 Message-Id: <20230302052511.1918-24-xin3.li@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230302052511.1918-1-xin3.li@intel.com> References: <20230302052511.1918-1-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