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 A4FC4E81DFE for ; Fri, 6 Oct 2023 14:03:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232494AbjJFODF (ORCPT ); Fri, 6 Oct 2023 10:03:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232335AbjJFODD (ORCPT ); Fri, 6 Oct 2023 10:03:03 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A321B6 for ; Fri, 6 Oct 2023 07:03:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696600982; x=1728136982; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ewD5kzNxcEnCXxH4YfAN7BLpYeNQYIs6YHElrCZx5sE=; b=nPM+EmMD3Wf9YFp9ozJRVueygp8Ag2B7+K306F7fg2OWgUxmE8OOmPQ5 1G3LcE5/tcOSEN7ACpYc0XrJqQNkFtxKtevNzAGBTigLCtP3xw4I9mlua 0hRNUY8DSpPhRqxUQYiHP0lR7VECodBI4VaA56RCoJgkUHF1P2oG2/Su4 e2qBGfKrl7WqqHa4nWhue25EyFi2LY2SkaEVVYZFfuc64ohLkfe3PvgSe 8pF0stqBdv4UXdWD9mHo4Qg2z1oKiTdT3hC8HKbsypRtZthMF2zXFJ1Wd IoqFjHZD0KA0VurqYCk9IIUb8+w7QJkBLC89lnR102mkK13IJwIv+Gv4l g==; X-IronPort-AV: E=McAfee;i="6600,9927,10855"; a="368831335" X-IronPort-AV: E=Sophos;i="6.03,204,1694761200"; d="scan'208";a="368831335" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Oct 2023 07:02:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10855"; a="745873746" X-IronPort-AV: E=Sophos;i="6.03,204,1694761200"; d="scan'208";a="745873746" Received: from dhimanbh-mobl1.amr.corp.intel.com (HELO [10.209.88.92]) ([10.209.88.92]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Oct 2023 07:02:49 -0700 Message-ID: <2d952c6b-2357-208b-e816-bca19c2a7ca6@intel.com> Date: Fri, 6 Oct 2023 07:02:48 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH] x86/tdx: Override the tsc calibration for TDX VMs Content-Language: en-US To: Vishal Annapurve , "Kirill A. Shutemov" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Peter Zijlstra , Jun Nakajima , Isaku Yamahata , Erdem Aktas , Sagi Shahar Cc: Sean Christopherson , Nikolay Borisov , "Jason A. Donenfeld" , Kuppuswamy Sathyanarayanan , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org References: <20231006011255.4163884-1-vannapurve@google.com> From: Dave Hansen In-Reply-To: <20231006011255.4163884-1-vannapurve@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/5/23 18:12, Vishal Annapurve wrote: > +/** > + * Determine TSC frequency via CPUID, else return 0. > + */ > +static unsigned long tdx_calibrate_tsc(void) > +{ > + unsigned int eax_denominator = 0, ebx_numerator = 0, ecx_hz = 0, edx = 0; > + unsigned int crystal_khz; > + > + /* CPUID 15H TSC/Crystal ratio, plus optionally Crystal Hz */ > + cpuid(0x15, &eax_denominator, &ebx_numerator, &ecx_hz, &edx); > + > + if (ebx_numerator == 0 || eax_denominator == 0) > + return 0; > + > + crystal_khz = ecx_hz / 1000; > + > + /* > + * TSC frequency reported directly by CPUID is a "hardware reported" > + * frequency and is the most accurate one so far we have. This > + * is considered a known frequency. > + */ > + if (crystal_khz != 0) > + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); > + > + return crystal_khz * ebx_numerator / eax_denominator; > +} > + Would it be possible to do this by refactoring the existing code and calling it directly instead of copying and pasting so much?