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 86DC5C54EE9 for ; Wed, 7 Sep 2022 15:12:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230429AbiIGPMU (ORCPT ); Wed, 7 Sep 2022 11:12:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230383AbiIGPMI (ORCPT ); Wed, 7 Sep 2022 11:12:08 -0400 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA34F5FAEB; Wed, 7 Sep 2022 08:12:05 -0700 (PDT) Received: by mail-pl1-x636.google.com with SMTP id u22so14839075plq.12; Wed, 07 Sep 2022 08:12:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=5qlPV74Pp3Ds4k5ap0cTIGdjJPYtwt6BD4m9h1Xc3wk=; b=g/oUwG7nDZnAY+SRO6rmpt7UgcU1TOLPhiiSgR2bw8ahfwXIMNyRkQhYP1t6pYAWTM aHp4x9x0/2FncovxGQvthm7APBEysbwJiqseWxd6YVyppa0csAAvTXjum2TR1bQMvW1Y TsLmcLeCz4KsYlyQ7wtbJOuA8lkWOzPFV4IpfsU4AvkL81hBLPvakmohZ+Ftc4XxHDed 6Xwp7Mn1Q0YCpR/AKLGqU+aFv8/Lfc/auZUPK6cs1L73VT4FcejgR9WIuPhXsmLS0tWV mk7ySj+HL7wlFZjK4GqWjjGBeh0GQ1oYd7DcWb+U4mA4joVl3NBC53iMz26010VVcJpO eiOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=5qlPV74Pp3Ds4k5ap0cTIGdjJPYtwt6BD4m9h1Xc3wk=; b=3cPNI9TrSvCtZeKnrQ3fsItrEoGAWTIFU9/3hY+1Fxv53msg2zSfpxTbyEcj/fDfqi I+xLddsAF0h9pX6aCO7gsBTAIgHj0dah2A69YeIke9JS8k16Fl3SrwckB+h03/uAZf8y phS/08kjZpWr13sWWLlLqVUg+sc2fzKO9kvye2ceAIaszPtqhV5ikeILxNdYw+kZJcv9 ct3iUPxRfH3yACQebJLhFhUnTlekIzlweO8UoBKUbO4hXZ6RBmvLT/siBteVp1Rmbggt n7VfJSlBba6pphOP18StWG3wJ6b3fTA+nGpuKNSwY3R8p/xdtXZFddxvD54d/TcLIEc8 HweA== X-Gm-Message-State: ACgBeo22tkVdmHEMssRKeRF2Jyzys91qCALIDHOO+YFr5SSsCtkOlEq3 lv0SdHYhtS2k73dtwbDzGFg= X-Google-Smtp-Source: AA6agR6diMWa4vKZ7Z2eUcq9sBc3jDRr7sDRWe6tvb628y0j9mUtz05EnKrEHAXrHxghNRqjThUp/g== X-Received: by 2002:a17:903:11c9:b0:172:6ea1:b727 with SMTP id q9-20020a17090311c900b001726ea1b727mr4457187plh.78.1662563525027; Wed, 07 Sep 2022 08:12:05 -0700 (PDT) Received: from localhost ([192.55.55.51]) by smtp.gmail.com with ESMTPSA id x20-20020aa79574000000b0053dec787698sm5827300pfq.175.2022.09.07.08.12.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Sep 2022 08:12:04 -0700 (PDT) Date: Wed, 7 Sep 2022 08:12:03 -0700 From: Isaku Yamahata To: Marc Zyngier Cc: Yuan Yao , isaku.yamahata@intel.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Will Deacon , isaku.yamahata@gmail.com, Kai Huang , Chao Gao , Atish Patra , Shaokun Zhang , Qi Liu , John Garry , Daniel Lezcano , Huang Ying , Huacai Chen , Dave Hansen , Borislav Petkov , Oliver Upton Subject: Re: [PATCH v3 06/22] KVM: arm64: Simplify the CPUHP logic Message-ID: <20220907151203.GA456048@ls.amr.corp.intel.com> References: <72481a7bc0ff08093f4f0f04cece877ee82de0cf.1662084396.git.isaku.yamahata@intel.com> <20220905070509.f5neutyqgvbklefi@yy-desk-7060> <87pmgaqie6.wl-maz@kernel.org> <3cc7a3dffa4f12c4aa1f546f3e2d3952@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <3cc7a3dffa4f12c4aa1f546f3e2d3952@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 05, 2022 at 01:39:20PM +0100, Marc Zyngier wrote: > On 2022-09-05 10:29, Marc Zyngier wrote: > > On Mon, 05 Sep 2022 08:05:09 +0100, > > Yuan Yao wrote: > > > > > > On Thu, Sep 01, 2022 at 07:17:41PM -0700, isaku.yamahata@intel.com > > > wrote: > > > > From: Marc Zyngier > > > > > > > > For a number of historical reasons, the KVM/arm64 hotplug setup is pretty > > > > complicated, and we have two extra CPUHP notifiers for vGIC and timers. > > > > > > > > It looks pretty pointless, and gets in the way of further changes. > > > > So let's just expose some helpers that can be called from the core > > > > CPUHP callback, and get rid of everything else. > > > > > > > > This gives us the opportunity to drop a useless notifier entry, > > > > as well as tidy-up the timer enable/disable, which was a bit odd. > > > > > > > > Signed-off-by: Marc Zyngier > > > > Signed-off-by: Chao Gao > > > > Reviewed-by: Oliver Upton > > > > Link: https://lore.kernel.org/r/20220216031528.92558-5-chao.gao@intel.com > > > > Signed-off-by: Isaku Yamahata > > > > --- > > > > arch/arm64/kvm/arch_timer.c | 27 ++++++++++----------------- > > > > arch/arm64/kvm/arm.c | 4 ++++ > > > > arch/arm64/kvm/vgic/vgic-init.c | 19 ++----------------- > > > > include/kvm/arm_arch_timer.h | 4 ++++ > > > > include/kvm/arm_vgic.h | 4 ++++ > > > > include/linux/cpuhotplug.h | 3 --- > > > > 6 files changed, 24 insertions(+), 37 deletions(-) > > > > > > > > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c > > > > index bb24a76b4224..33fca1a691a5 100644 > > > > --- a/arch/arm64/kvm/arch_timer.c > > > > +++ b/arch/arm64/kvm/arch_timer.c > > > > @@ -811,10 +811,18 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu) > > > > ptimer->host_timer_irq_flags = host_ptimer_irq_flags; > > > > } > > > > > > > > -static void kvm_timer_init_interrupt(void *info) > > > > +void kvm_timer_cpu_up(void) > > > > { > > > > enable_percpu_irq(host_vtimer_irq, host_vtimer_irq_flags); > > > > - enable_percpu_irq(host_ptimer_irq, host_ptimer_irq_flags); > > > > + if (host_ptimer_irq) > > > > + enable_percpu_irq(host_ptimer_irq, host_ptimer_irq_flags); > > > > +} > > > > + > > > > +void kvm_timer_cpu_down(void) > > > > +{ > > > > + disable_percpu_irq(host_vtimer_irq); > > > > + if (host_ptimer_irq) > > > > + disable_percpu_irq(host_ptimer_irq); > > > > } > > > > > > Should "host_vtimer_irq" be checked yet as host_ptimer_irq ? > > > > No, because although the ptimer interrupt is optional (on older > > systems, we fully emulate that timer, including the interrupt), the > > vtimer interrupt is always present and can be used unconditionally. > > > > > Because > > > the host_{v,p}timer_irq is set in same function kvm_irq_init() which > > > called AFTER the on_each_cpu(_kvm_arch_hardware_enable, NULL, 1) from > > > init_subsystems(): > > > > > > kvm_init() > > > kvm_arch_init() > > > init_subsystems() > > > on_each_cpu(_kvm_arch_hardware_enable, NULL, 1); > > > kvm_timer_hyp_init() > > > kvm_irq_init() > > > host_vtimer_irq = info->virtual_irq; > > > host_ptimer_irq = info->physical_irq; > > > hardware_enable_all() > > > > This, however, is a very nice catch. I doubt this results in anything > > really bad (the interrupt enable will fail as the interrupt number > > is 0, and the disable will also fail due to no prior enable), but > > that's extremely ugly anyway. > > > > The best course of action AFAICS is to differentiate between the > > arm64-specific initialisation (which is a one-off) and the runtime > > stuff. Something like the hack below, that I haven't tested yet: > > > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > > index 32c1022eb4b3..65d03c28f32a 100644 > > --- a/arch/arm64/kvm/arm.c > > +++ b/arch/arm64/kvm/arm.c > > @@ -1671,23 +1671,27 @@ static void _kvm_arch_hardware_enable(void > > *discard) > > { > > if (!__this_cpu_read(kvm_arm_hardware_enabled)) { > > cpu_hyp_reinit(); > > - kvm_vgic_cpu_up(); > > - kvm_timer_cpu_up(); > > __this_cpu_write(kvm_arm_hardware_enabled, 1); > > } > > } > > > > int kvm_arch_hardware_enable(void) > > { > > + int was_enabled = __this_cpu_read(kvm_arm_hardware_enabled); > > + > > _kvm_arch_hardware_enable(NULL); > > + > > + if (!was_enabled) { > > + kvm_vgic_cpu_up(); > > + kvm_timer_cpu_up(); > > + } > > + > > return 0; > > } > > > > static void _kvm_arch_hardware_disable(void *discard) > > { > > if (__this_cpu_read(kvm_arm_hardware_enabled)) { > > - kvm_timer_cpu_down(); > > - kvm_vgic_cpu_down(); > > cpu_hyp_reset(); > > __this_cpu_write(kvm_arm_hardware_enabled, 0); > > } > > @@ -1695,6 +1699,11 @@ static void _kvm_arch_hardware_disable(void > > *discard) > > > > void kvm_arch_hardware_disable(void) > > { > > + if (__this_cpu_read(kvm_arm_hardware_enabled)) { > > + kvm_timer_cpu_down(); > > + kvm_vgic_cpu_down(); > > + } > > + > > if (!is_protected_kvm_enabled()) > > _kvm_arch_hardware_disable(NULL); > > } > > OK, this seems to work here, at least based on a sample of 2 > systems, bringing CPUs up and down whist a VM is pinned to > these CPUs. > > Isaku, can you please squash this into the original patch > and drop Oliver's Reviewed-by: tag, as this significantly > changes the logic? > > Alternatively, I can repost this patch as a standalone change. I'll do with the next respin. Anyway feel free to go before me. -- Isaku Yamahata