From patchwork Wed Mar 9 22:34:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Chang S. Bae" X-Patchwork-Id: 12775684 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 3F29AC433F5 for ; Wed, 9 Mar 2022 22:42:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229965AbiCIWnm (ORCPT ); Wed, 9 Mar 2022 17:43:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229908AbiCIWnm (ORCPT ); Wed, 9 Mar 2022 17:43:42 -0500 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7BFC511C38; Wed, 9 Mar 2022 14:42:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646865761; x=1678401761; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=ruPtGiXXQdOvROYpaC01TgDVkmf4NhGWvn3Yv1zkvtA=; b=OpbbHWCLJ2/kOG1K5Hkrcrf8ObXjd6DDzMZO8olHqmyM3buekI5hmLMe vn9MnLWEIU5N3zpjiyHYd2ow48SOvJew3UCYgfg0yigtzsFAzZHB+VLYA SQ/fdZqWyB3Ca0ZA1Ic62VZ9LcNZYPtu0S9bvgf+aLoTB49Dx7FwspRyY QuMgEDIC7w/dHKrMEe6MJ1URAviRqZj7OBZxtn+JJlXsXxmAsbkkwgtiQ fKIcK7Tf6jlVFLOn9NpPFerY1zWeFMpRTfXXmxnaBD290NEpq5USU/yGg 7XmfdYTZxOC+fADCQUTJoXaKWhszqyTUAe4Txrtksh3BIpAAvFU/WtBCs w==; X-IronPort-AV: E=McAfee;i="6200,9189,10281"; a="253938954" X-IronPort-AV: E=Sophos;i="5.90,168,1643702400"; d="scan'208";a="253938954" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Mar 2022 14:42:40 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,168,1643702400"; d="scan'208";a="554329567" Received: from chang-linux-3.sc.intel.com ([172.25.112.114]) by orsmga008.jf.intel.com with ESMTP; 09 Mar 2022 14:42:39 -0800 From: "Chang S. Bae" To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-pm@vger.kernel.org Cc: tglx@linutronix.de, dave.hansen@linux.intel.com, peterz@infradead.org, bp@alien8.de, rafael@kernel.org, ravi.v.shankar@intel.com, chang.seok.bae@intel.com Subject: [PATCH v2 1/2] x86/fpu: Add a helper to prepare AMX state for low-power CPU idle Date: Wed, 9 Mar 2022 14:34:30 -0800 Message-Id: <20220309223431.26560-2-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220309223431.26560-1-chang.seok.bae@intel.com> References: <20220309223431.26560-1-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org When a CPU enters an idle state, non-initialized states left in large registers may be the cause of preventing deeper low-power states. The new helper ensures the AMX state is initialized to make the CPU ready for low-power states. It will be used by the intel idle driver. Signed-off-by: Chang S. Bae Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v1: * Check the dynamic state flag first, to avoid #UD with XGETBV(1). Dependency on the opcode map update: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=x86/misc&id=9dd94df75b30eca03ed2151dd5bbc152a6f19abf --- arch/x86/include/asm/fpu/api.h | 2 ++ arch/x86/include/asm/special_insns.h | 9 +++++++++ arch/x86/kernel/fpu/core.c | 15 +++++++++++++++ 3 files changed, 26 insertions(+) diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index c83b3020350a..df48912fd1c8 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -165,4 +165,6 @@ static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) struct task_struct; extern long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2); +extern void fpu_idle_fpregs(void); + #endif /* _ASM_X86_FPU_API_H */ diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 68c257a3de0d..d434fbaeb3ff 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -294,6 +294,15 @@ static inline int enqcmds(void __iomem *dst, const void *src) return 0; } +static inline void tile_release(void) +{ + /* + * Instruction opcode for TILERELEASE; supported in binutils + * version >= 2.36. + */ + asm volatile(".byte 0xc4, 0xe2, 0x78, 0x49, 0xc0"); +} + #endif /* __KERNEL__ */ #endif /* _ASM_X86_SPECIAL_INSNS_H */ diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 8dea01ffc5c1..572dfa962b7b 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -847,3 +847,18 @@ int fpu__exception_code(struct fpu *fpu, int trap_nr) */ return 0; } + +/* + * Initialize register state that may prevent from entering low-power idle. + * This function will be invoked from the cpuidle driver only when needed. + */ +void fpu_idle_fpregs(void) +{ + if (!fpu_state_size_dynamic()) + return; + + if (xfeatures_in_use() & XFEATURE_MASK_XTILE) { + tile_release(); + fpregs_deactivate(¤t->thread.fpu); + } +}