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=-24.9 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,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=ham 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 807F9C432BE for ; Thu, 5 Aug 2021 06:41:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CCAB60EC0 for ; Thu, 5 Aug 2021 06:41:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233122AbhHEGlj (ORCPT ); Thu, 5 Aug 2021 02:41:39 -0400 Received: from linux.microsoft.com ([13.77.154.182]:46114 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232009AbhHEGlj (ORCPT ); Thu, 5 Aug 2021 02:41:39 -0400 Received: from [192.168.1.87] (unknown [223.178.56.171]) by linux.microsoft.com (Postfix) with ESMTPSA id C7362209DDB5; Wed, 4 Aug 2021 23:41:21 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com C7362209DDB5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1628145685; bh=bxasqC6P0Nvva5TxrwG2pE0QRcDHzuqT0kjeJsO27pQ=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=QwuKrkAVcWbIjWtac1uUOg/R8BefILIXAelMWOhnnv4BzMJuJhQVDwwOn4HEmcRYZ EUmEH/94W6TRrHPaHlPacVbZFznSRF2ZaafIhlD9xVNuAsTdHozQurVBeAhrbwoV2U VTg0HRqFV9jhf6deaslvhYRh1xNj01Q418Y0Ecb4= Subject: Re: [PATCH] x86/Hyper-V: Initialize Hyper-V stimer after enabling lapic To: Tianyu Lan , kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, michael.h.kelley@microsoft.com Cc: Tianyu Lan , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, vkuznets@redhat.com References: <20210804184843.513524-1-ltykernel@gmail.com> From: Praveen Kumar Message-ID: Date: Thu, 5 Aug 2021 12:11:18 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210804184843.513524-1-ltykernel@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 05-08-2021 00:18, Tianyu Lan wrote: > From: Tianyu Lan > > Hyper-V Isolation VM doesn't have PIT/HPET legacy timer and only > provide stimer. Initialize Hyper-v stimer just after enabling > lapic to avoid kernel stuck during calibrating TSC due to no > available timer. > > Signed-off-by: Tianyu Lan > --- > arch/x86/hyperv/hv_init.c | 29 ----------------------------- > arch/x86/kernel/cpu/mshyperv.c | 22 ++++++++++++++++++++++ > 2 files changed, 22 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c > index 6f247e7e07eb..4a643a85d570 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -271,25 +271,6 @@ static struct syscore_ops hv_syscore_ops = { > .resume = hv_resume, > }; > > -static void (* __initdata old_setup_percpu_clockev)(void); > - > -static void __init hv_stimer_setup_percpu_clockev(void) > -{ > - /* > - * Ignore any errors in setting up stimer clockevents > - * as we can run with the LAPIC timer as a fallback. > - */ > - (void)hv_stimer_alloc(false); > - > - /* > - * Still register the LAPIC timer, because the direct-mode STIMER is > - * not supported by old versions of Hyper-V. This also allows users > - * to switch to LAPIC timer via /sys, if they want to. > - */ > - if (old_setup_percpu_clockev) > - old_setup_percpu_clockev(); > -} > - > static void __init hv_get_partition_id(void) > { > struct hv_get_partition_id *output_page; > @@ -396,16 +377,6 @@ void __init hyperv_init(void) > wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); > } > > - /* > - * hyperv_init() is called before LAPIC is initialized: see > - * apic_intr_mode_init() -> x86_platform.apic_post_init() and > - * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER > - * depends on LAPIC, so hv_stimer_alloc() should be called from > - * x86_init.timers.setup_percpu_clockev. > - */ > - old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev; > - x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev; > - > hv_apic_init(); > > x86_init.pci.arch_init = hv_pci_init; > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c > index 6b5835a087a3..dcfbd2770d7f 100644 > --- a/arch/x86/kernel/cpu/mshyperv.c > +++ b/arch/x86/kernel/cpu/mshyperv.c > @@ -214,6 +214,20 @@ static void __init hv_smp_prepare_boot_cpu(void) > #endif > } > > +static void (* __initdata old_setup_initr_mode)(void); > + > +static void __init hv_setup_initr_mode(void) > +{ > + if (old_setup_initr_mode) > + old_setup_initr_mode(); > + > + /* > + * The direct-mode STIMER depends on LAPIC and so allocate > + * STIMER after calling initr node callback. > + */ > + (void)hv_stimer_alloc(false); In my understanding, in previous implementation we were ignoring the return error as there was a fallback handling for LAPIC. However, I'm not seeing the same here, or am I missing something ? > +} > + > static void __init hv_smp_prepare_cpus(unsigned int max_cpus) > { > #ifdef CONFIG_X86_64 > @@ -424,6 +438,7 @@ static void __init ms_hyperv_init_platform(void) > /* Register Hyper-V specific clocksource */ > hv_init_clocksource(); > #endif > + > /* > * TSC should be marked as unstable only after Hyper-V > * clocksource has been initialized. This ensures that the > @@ -431,6 +446,13 @@ static void __init ms_hyperv_init_platform(void) > */ > if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT)) > mark_tsc_unstable("running on Hyper-V"); > + > + /* > + * Override initr mode callback in order to allocate STIMER > + * after initalizing LAPIC. > + */ > + old_setup_initr_mode = x86_init.irqs.intr_mode_init; > + x86_init.irqs.intr_mode_init = hv_setup_initr_mode; > } > > static bool __init ms_hyperv_x2apic_available(void) > Regards, ~Praveen.