From patchwork Wed Jun 8 16:47:47 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: 580114 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 28A2FC43334 for ; Wed, 8 Jun 2022 17:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229446AbiFHRLx (ORCPT ); Wed, 8 Jun 2022 13:11:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229980AbiFHRKs (ORCPT ); Wed, 8 Jun 2022 13:10:48 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6289C3FBBCE; Wed, 8 Jun 2022 09:56:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1654707412; x=1686243412; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=F4L0RjTrL9ocDlqPulFosaCzsuwH2sWkXHYM3jpPmOo=; b=lNsUY7D7F5So1YpLz2U6+df9bddJRo3ZYnp2D+u8SGKDhfwApqfGG+LP qIRzBbf/hMmj0zO+EhUDwLtBZXiYd0DAKbtF0CorJYn2Ge/jacOHYlBS6 j5j5UicSD65zk1tnEDGaaeHGZzB+AuSb1/Av2BUoRB3N9O6F+9C0giY+v 9ncZvKXbjCreZccwPKQeDBP/aJkn3ym82DLoW2xE8m4DZ4FEbENMysgLi CIL+UljYFN54ZRwX/7+WaBdXrI04+fxZu6GAjbJGNrLSCGkuDYuGTqf+L uPJZ/0DJZmiTs/lxx69UPKiS8nscA275NRJLLcPVHlpnIPvr3HNUaXiDf Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10372"; a="265768316" X-IronPort-AV: E=Sophos;i="5.91,286,1647327600"; d="scan'208";a="265768316" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2022 09:56:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,286,1647327600"; d="scan'208";a="585001329" Received: from chang-linux-3.sc.intel.com ([172.25.66.173]) by fmsmga007.fm.intel.com with ESMTP; 08 Jun 2022 09:56:51 -0700 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, riel@fb.com, bigeasy@linutronix.de, hch@lst.de, fenghua.yu@intel.com, rui.zhang@intel.com, artem.bityutskiy@linux.intel.com, jacob.jun.pan@linux.intel.com, lenb@kernel.org, chang.seok.bae@intel.com Subject: [PATCH v5 1/2] x86/fpu: Add a helper to prepare AMX state for low-power CPU idle Date: Wed, 8 Jun 2022 09:47:47 -0700 Message-Id: <20220608164748.11864-2-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220608164748.11864-1-chang.seok.bae@intel.com> References: <20220608164748.11864-1-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org When a CPU enters an idle state, a non-initialized AMX register state may be the cause of preventing a deeper low-power state. Other extended register states whether initialized or not do not impact the CPU idle state. The new helper can ensure the AMX state is initialized before the CPU is idle, and it will be used by the intel idle driver. Check the AMX_TILE feature bit before using XGETBV1 as a chain of dependencies was established via cpuid_deps[]: AMX->XFD->XGETBV1. Signed-off-by: Chang S. Bae Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Cc: Rik van Riel Cc: Sebastian Andrzej Siewior Cc: Christoph Hellwig Cc: Fenghua Yu --- Changes from v4: * Switch to check the AMX_TILE flag instead XGETBV1 (Dave Hansen). * Massage the changelog. Changes from v3: * Call out AMX state in changelog (Thomas Glexiner). Changes from v2: * Check the feature flag instead of fpu_state_size_dynamic() (Dave Hansen). Changes from v1: * Check the dynamic state flag first, to avoid #UD with XGETBV(1). --- arch/x86/include/asm/fpu/api.h | 2 ++ arch/x86/include/asm/special_insns.h | 9 +++++++++ arch/x86/kernel/fpu/core.c | 14 ++++++++++++++ 3 files changed, 25 insertions(+) diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index 6b0f31fb53f7..503a577814b2 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -164,4 +164,6 @@ static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) /* prctl */ extern long fpu_xstate_prctl(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 45b18eb94fa1..35f709f619fb 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -295,6 +295,15 @@ 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 0531d6a06df5..3b28c5b25e12 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -851,3 +851,17 @@ 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) +{ + /* Note: AMX_TILE being enabled implies XGETBV1 support */ + if (cpu_feature_enabled(X86_FEATURE_AMX_TILE) && + (xfeatures_in_use() & XFEATURE_MASK_XTILE)) { + tile_release(); + fpregs_deactivate(¤t->thread.fpu); + } +}