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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 1768CC64EB8 for ; Tue, 9 Oct 2018 09:31:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54BB5214C5 for ; Tue, 9 Oct 2018 09:31:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54BB5214C5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726910AbeJIQrG (ORCPT ); Tue, 9 Oct 2018 12:47:06 -0400 Received: from terminus.zytor.com ([198.137.202.136]:51589 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726483AbeJIQrG (ORCPT ); Tue, 9 Oct 2018 12:47:06 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w999Usul980587 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 9 Oct 2018 02:30:54 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w999Uscb980581; Tue, 9 Oct 2018 02:30:54 -0700 Date: Tue, 9 Oct 2018 02:30:54 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Yi Sun Message-ID: Cc: sthemmin@microsoft.com, tglx@linutronix.de, yi.y.sun@linux.intel.com, kys@microsoft.com, jgross@suse.com, mingo@kernel.org, haiyangz@microsoft.com, Michael.H.Kelley@microsoft.com, hpa@zytor.com, linux-kernel@vger.kernel.org Reply-To: linux-kernel@vger.kernel.org, hpa@zytor.com, haiyangz@microsoft.com, Michael.H.Kelley@microsoft.com, mingo@kernel.org, jgross@suse.com, kys@microsoft.com, yi.y.sun@linux.intel.com, sthemmin@microsoft.com, tglx@linutronix.de In-Reply-To: <1538987374-51217-3-git-send-email-yi.y.sun@linux.intel.com> References: <1538987374-51217-3-git-send-email-yi.y.sun@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/hyperv] x86/hyperv: Enable PV qspinlock for Hyper-V Git-Commit-ID: b36bcb7ce0b353bd4889e06b61e036744b02ca51 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b36bcb7ce0b353bd4889e06b61e036744b02ca51 Gitweb: https://git.kernel.org/tip/b36bcb7ce0b353bd4889e06b61e036744b02ca51 Author: Yi Sun AuthorDate: Mon, 8 Oct 2018 16:29:34 +0800 Committer: Thomas Gleixner CommitDate: Tue, 9 Oct 2018 11:26:31 +0200 x86/hyperv: Enable PV qspinlock for Hyper-V Implement the required wait and kick callbacks to support PV spinlocks in Hyper-V guests. [ tglx: Document the requirement for disabling interrupts in the wait() callback. Remove goto and unnecessary includes. Add prototype for hv_vcpu_is_preempted(). ] Signed-off-by: Yi Sun Signed-off-by: Thomas Gleixner Reviewed-by: Juergen Gross Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Cc: Michael Kelley (EOSG) Cc: chao.p.peng@intel.com Cc: chao.gao@intel.com Cc: isaku.yamahata@intel.com Cc: tianyu.lan@microsoft.com Link: https://lkml.kernel.org/r/1538987374-51217-3-git-send-email-yi.y.sun@linux.intel.com --- Documentation/admin-guide/kernel-parameters.txt | 5 ++ arch/x86/hyperv/Makefile | 4 ++ arch/x86/hyperv/hv_spinlock.c | 88 +++++++++++++++++++++++++ arch/x86/include/asm/mshyperv.h | 2 + arch/x86/kernel/cpu/mshyperv.c | 14 ++++ 5 files changed, 113 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 92eb1f42240d..ca6ca93e8281 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1385,6 +1385,11 @@ hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. If specified, z/VM IUCV HVC accepts connections from listed z/VM user IDs only. + + hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations + which allow the hypervisor to 'idle' the + guest on lock contention. + keep_bootcon [KNL] Do not unregister boot console at start. This is only useful for debugging when something happens in the window diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile index b21ee65c4101..1c11f9420a82 100644 --- a/arch/x86/hyperv/Makefile +++ b/arch/x86/hyperv/Makefile @@ -1,2 +1,6 @@ obj-y := hv_init.o mmu.o nested.o obj-$(CONFIG_X86_64) += hv_apic.o + +ifdef CONFIG_X86_64 +obj-$(CONFIG_PARAVIRT_SPINLOCKS) += hv_spinlock.o +endif diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c new file mode 100644 index 000000000000..2b6382cbb769 --- /dev/null +++ b/arch/x86/hyperv/hv_spinlock.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Hyper-V specific spinlock code. + * + * Copyright (C) 2018, Intel, Inc. + * + * Author : Yi Sun + */ + +#define pr_fmt(fmt) "Hyper-V: " fmt + +#include + +#include +#include +#include + +static bool __initdata hv_pvspin = true; + +static void hv_qlock_kick(int cpu) +{ + apic->send_IPI(cpu, X86_PLATFORM_IPI_VECTOR); +} + +static void hv_qlock_wait(u8 *byte, u8 val) +{ + unsigned long msr_val; + unsigned long flags; + + if (in_nmi()) + return; + + /* + * Reading HV_X64_MSR_GUEST_IDLE MSR tells the hypervisor that the + * vCPU can be put into 'idle' state. This 'idle' state is + * terminated by an IPI, usually from hv_qlock_kick(), even if + * interrupts are disabled on the vCPU. + * + * To prevent a race against the unlock path it is required to + * disable interrupts before accessing the HV_X64_MSR_GUEST_IDLE + * MSR. Otherwise, if the IPI from hv_qlock_kick() arrives between + * the lock value check and the rdmsrl() then the vCPU might be put + * into 'idle' state by the hypervisor and kept in that state for + * an unspecified amount of time. + */ + local_irq_save(flags); + /* + * Only issue the rdmsrl() when the lock state has not changed. + */ + if (READ_ONCE(*byte) == val) + rdmsrl(HV_X64_MSR_GUEST_IDLE, msr_val); + local_irq_restore(flags); +} + +/* + * Hyper-V does not support this so far. + */ +bool hv_vcpu_is_preempted(int vcpu) +{ + return false; +} +PV_CALLEE_SAVE_REGS_THUNK(hv_vcpu_is_preempted); + +void __init hv_init_spinlocks(void) +{ + if (!hv_pvspin || !apic || + !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) || + !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) { + pr_info("PV spinlocks disabled\n"); + return; + } + pr_info("PV spinlocks enabled\n"); + + __pv_init_lock_hash(); + pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_lock_ops.wait = hv_qlock_wait; + pv_lock_ops.kick = hv_qlock_kick; + pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(hv_vcpu_is_preempted); +} + +static __init int hv_parse_nopvspin(char *arg) +{ + hv_pvspin = false; + return 0; +} +early_param("hv_nopvspin", hv_parse_nopvspin); diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index f37704497d8f..0d6271cce198 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -351,6 +351,8 @@ int hyperv_flush_guest_mapping(u64 as); #ifdef CONFIG_X86_64 void hv_apic_init(void); +void __init hv_init_spinlocks(void); +bool hv_vcpu_is_preempted(int vcpu); #else static inline void hv_apic_init(void) {} #endif diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index ad12733f6058..2179c7efc1f4 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -199,6 +199,16 @@ static unsigned long hv_get_tsc_khz(void) return freq / 1000; } +#if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV) +static void __init hv_smp_prepare_boot_cpu(void) +{ + native_smp_prepare_boot_cpu(); +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) + hv_init_spinlocks(); +#endif +} +#endif + static void __init ms_hyperv_init_platform(void) { int hv_host_info_eax; @@ -303,6 +313,10 @@ static void __init ms_hyperv_init_platform(void) if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) alloc_intr_gate(HYPERV_STIMER0_VECTOR, hv_stimer0_callback_vector); + +# if defined(CONFIG_SMP) + smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu; +# endif #endif }