From mboxrd@z Thu Jan 1 00:00:00 1970 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 0DFA2EDE989 for ; Thu, 14 Sep 2023 06:28:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235605AbjING25 (ORCPT ); Thu, 14 Sep 2023 02:28:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235344AbjING2r (ORCPT ); Thu, 14 Sep 2023 02:28:47 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A873F9; Wed, 13 Sep 2023 23:28:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694672923; x=1726208923; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RiRpO69NN4+D9BiPv1b8kqQ9mDIXR5b5ZIvKZMvuZW0=; b=Tc7YvM78ki119DQU8AXTlj+eR6/WKAiafjX5L7+z2qE3GEXOq9jNAb9F LK1Xlv0rJbOFt1HBHw9fpyQTep7eu3aG/LmvqUlqLHyUETpiUtYr1JMvG WhwK6f9qoSkxPVFFMLBTwRujZMP/zfzkIQmXbjFikI4YIT63NIpFZyIMb X/UPS+5KfqbqoEYOmCJYo0m2tFg04J/SZyLUO3VXgvbY3g8woIQ1zCw2Q 4BgnjLefwfOZ4C08JiuckohhbEu6NpjoQpuwuXlrmqDEAs3JEfh1lzQ/o ur7IIq3IThxbA2C/4uc4w/devaRlmdUKvbiTqoJrM5CZbproC/cwPrrnU w==; X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="382672455" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="382672455" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 23:28:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10832"; a="809937987" X-IronPort-AV: E=Sophos;i="6.02,145,1688454000"; d="scan'208";a="809937987" Received: from embargo.jf.intel.com ([10.165.9.183]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2023 23:28:42 -0700 From: Yang Weijiang To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: dave.hansen@intel.com, tglx@linutronix.de, peterz@infradead.org, seanjc@google.com, pbonzini@redhat.com, rick.p.edgecombe@intel.com, kvm@vger.kernel.org, yang.zhong@intel.com, jing2.liu@intel.com, chao.gao@intel.com, Yang Weijiang Subject: [RFC PATCH 4/8] x86/fpu/xstate: Introduce kernel dynamic xfeature set Date: Wed, 13 Sep 2023 23:23:30 -0400 Message-Id: <20230914032334.75212-5-weijiang.yang@intel.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20230914032334.75212-1-weijiang.yang@intel.com> References: <20230914032334.75212-1-weijiang.yang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Define a new kernel xfeature set including the features can be dynamically enabled, i.e., the relevant feature is enabled on demand. The xfeature set is currently used by KVM to configure __guest__ fpstate, i.e., calculating the xfeature and fpstate storage size etc. The xfeature set is initialized once and used whenever it's referenced to avoid repeat calculation. Currently it's used when 1) guest fpstate __state_size is calculated while guest permits are configured 2) guest vCPU is created and its fpstate is initialized. Suggested-by: Dave Hansen Signed-off-by: Yang Weijiang --- arch/x86/kernel/fpu/xstate.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index c3ed86732d33..eaec05bc1b3c 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -84,6 +84,8 @@ static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init; +u64 fpu_kernel_dynamic_xfeatures __ro_after_init; + #define XSTATE_FLAG_SUPERVISOR BIT(0) #define XSTATE_FLAG_ALIGNED64 BIT(1) @@ -740,6 +742,23 @@ static void __init fpu__init_disable_system_xstate(unsigned int legacy_size) fpstate_reset(¤t->thread.fpu); } +static unsigned short xsave_kernel_dynamic_xfeatures[] = { + [XFEATURE_CET_KERNEL] = X86_FEATURE_SHSTK, +}; + +static void __init init_kernel_dynamic_xfeatures(void) +{ + unsigned short cid; + int i; + + for (i = 0; i < ARRAY_SIZE(xsave_kernel_dynamic_xfeatures); i++) { + cid = xsave_kernel_dynamic_xfeatures[i]; + + if (cid && boot_cpu_has(cid)) + fpu_kernel_dynamic_xfeatures |= BIT_ULL(i); + } +} + /* * Enable and initialize the xsave feature. * Called once per system bootup. @@ -809,6 +828,8 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) if (boot_cpu_has(X86_FEATURE_SHSTK) || boot_cpu_has(X86_FEATURE_IBT)) fpu_kernel_cfg.max_features |= BIT_ULL(XFEATURE_CET_USER); + init_kernel_dynamic_xfeatures(); + if (!cpu_feature_enabled(X86_FEATURE_XFD)) fpu_kernel_cfg.max_features &= ~XFEATURE_MASK_USER_DYNAMIC; -- 2.27.0