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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27CE5C433E6 for ; Wed, 20 Jan 2021 16:18:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBF2C233E2 for ; Wed, 20 Jan 2021 16:18:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387950AbhATQSP (ORCPT ); Wed, 20 Jan 2021 11:18:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391344AbhATQOq (ORCPT ); Wed, 20 Jan 2021 11:14:46 -0500 Received: from mail-ed1-x529.google.com (mail-ed1-x529.google.com [IPv6:2a00:1450:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC513C0613C1 for ; Wed, 20 Jan 2021 08:14:04 -0800 (PST) Received: by mail-ed1-x529.google.com with SMTP id s11so19123297edd.5 for ; Wed, 20 Jan 2021 08:14:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Q3YaCJQ8LfKzkGjKHvvi/q44WKBCWlUY5g3M93ES9N4=; b=Qt+31s0k7Mjn6X5fLAPTZQBwGj66PX2q4gx9kZJM9UU0Fj9zKf9iGeB0nLS2LYGKMg LWmex1RpYlfY9c7UusCIbs5ju8pv3J++sSocIjMB0TZeXaiOMpwKWUVIWcYTMDBCKshV KjCry0XhhdgozhMjbeK7T8OsOyK3HHOJ+FpG/iMZXDHOmzjR91e20ux83TWKRlkXNvni weYgzqBxlQMq5jxc7aAh1xOhFkoVzr449eIWCGojiBzCQMwEra67oRs/VMHKqTTvdp1/ WqdjBF3YCBKno8Fy90iju+Cvm4YwOeOtDaQ98rEw5RykZWJLVHF0vaAlgEtzzw2llV+X YTzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Q3YaCJQ8LfKzkGjKHvvi/q44WKBCWlUY5g3M93ES9N4=; b=Om1Z2b5d3n+DlsibdVohrGnW61fVWxIeFbgHgeQHusoi2JgufmrfUcNL3ojVc5L4+y MwVEPiaQFRWaiJ9mNXjgIgiTT7SOjd6gKJwjK6XB07mEYvvhi20/qb2fbgjX3Mti3TLH Mz8GLZVUfT1IXRoHv+PBzpmaSXXnHDFgBqQhgPtSc0tBf7jaunmROlNF391AQWodbimL 7cXUwk0utk483o8Aj7KMmLdGvThUSlog7g22/wgPZc0PvAt3fKeR2NkpyojZceKUVG4+ yWTj8rwBr5XcgewpfMTZpPn/PlvCbOyjRwGlEti4WRwg4XWZEtq02s5oSAN3NlX2ZuZi T/6Q== X-Gm-Message-State: AOAM531TKmGjLYGr3JjRkDPNkJlnLLpb6dIrWhJ6DGQpapkNuO7NkPge IjfdfDQSuWQjrabAdB9DofGJ/50GWNRlJ11SJWwPnw== X-Google-Smtp-Source: ABdhPJwSZ/KSHBr1sBpNSdWGO8It3AqUEuSIdP5w2bhyco9/KW73LkGrKMnaE5mNEUQEA2lqr+GLf+3ATR5p3G98/nA= X-Received: by 2002:aa7:d803:: with SMTP id v3mr7702645edq.153.1611159243691; Wed, 20 Jan 2021 08:14:03 -0800 (PST) MIME-Version: 1.0 References: <20210120120058.29138-1-wei.liu@kernel.org> <20210120120058.29138-6-wei.liu@kernel.org> In-Reply-To: <20210120120058.29138-6-wei.liu@kernel.org> From: Pavel Tatashin Date: Wed, 20 Jan 2021 11:13:28 -0500 Message-ID: Subject: Re: [PATCH v5 05/16] clocksource/hyperv: use MSR-based access if running as root To: Wei Liu Cc: Linux on Hyper-V List , virtualization@lists.linux-foundation.org, Linux Kernel List , Michael Kelley , Vineeth Pillai , Sunil Muthuswamy , Nuno Das Neves , Daniel Lezcano , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 20, 2021 at 7:01 AM Wei Liu wrote: > > When Linux runs as the root partition, the setup required for TSC page > is different. Why would we need a TSC page as a clock source for root partition at all? I think the above can be removed. Luckily Linux also has access to the MSR based > clocksource. We can just disable the TSC page clocksource if Linux is > the root partition. > > Signed-off-by: Wei Liu > Acked-by: Daniel Lezcano > --- > drivers/clocksource/hyperv_timer.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c > index ba04cb381cd3..269a691bd2c4 100644 > --- a/drivers/clocksource/hyperv_timer.c > +++ b/drivers/clocksource/hyperv_timer.c > @@ -426,6 +426,9 @@ static bool __init hv_init_tsc_clocksource(void) > if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE)) > return false; > > + if (hv_root_partition) > + return false; > + Reviewed-by: Pavel Tatashin