From patchwork Tue Nov 7 10:47:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoffer Dall X-Patchwork-Id: 10046461 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EEAC860247 for ; Tue, 7 Nov 2017 11:06:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C840A29CE0 for ; Tue, 7 Nov 2017 11:06:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BD4A629D03; Tue, 7 Nov 2017 11:06:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 148A329CE0 for ; Tue, 7 Nov 2017 11:06:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=g5ntqURe0RcHTKYPKfTWCMVdzxzMIau9RzVFeGhX8G8=; b=FQlQzvbqQUTwSycEDEmo5C8zCT qe+33JsB3nEkOMNqkUVExXrpXchMOVkEIKG/aG7Usuuu7SSCGmLbCBDyLK4TeDKimPhRBb3DLqos4 Izzh6NAeDBYZoVqbDf8RMKoS+4C9JbMw1HLAbzz9Bb5gWndKhGP2J90l0qRVFTmEUpRQLsoJwgj3c pIr6OlJjVbpoAoU2avEMZoy2Ntd3qdA2T+7i0xmv+fDSf4AjmzYtbQHiJkCCu7qGbmWu7AHutR8b3 +pZR6l/jsN92scmzfFecHeoZt10Gf98qMnG3lznEI4lKByuVHCwwA6nPQRI0zL5vr7xO5iJiDh24c sEhum3Tg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1eC1hv-0002ae-Kx; Tue, 07 Nov 2017 11:06:15 +0000 Received: from mail-wm0-x244.google.com ([2a00:1450:400c:c09::244]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1eC1R2-000119-Mc for linux-arm-kernel@lists.infradead.org; Tue, 07 Nov 2017 10:49:04 +0000 Received: by mail-wm0-x244.google.com with SMTP id y83so2800112wmc.4 for ; Tue, 07 Nov 2017 02:48:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=arEqpL7EXtpqePmPPeIaYNvDP+Y7LQfvHsIEUe4lStA=; b=VgZp0t3z34qdjvOotTUdyV4prhYYAg3V/6AdN+WCxTDOJQxaRSwe2Cz9dWwR7bavu0 X+QAzkZzD/mMgrUTEq6bocVGDA/eIlk71hTHhjgGJjYiQW49bfWDCN4/b9VqQ/ESfuDb S2RRNbsh9jgzFAlogFIDfTZREJEsQ4sP/grGs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=arEqpL7EXtpqePmPPeIaYNvDP+Y7LQfvHsIEUe4lStA=; b=ZIRlpWpLkjUygDEArJ+LeuWhtOREqlYjmfdqiuHwKbfVnO/4jHlqscTGmj2utiyZmR 0hryZxAQb/LNJ9X8cvljkreQd9areFY1lMh6g4HIl/xeE7j+FHtdDPBFcS77Viul+LlN WJGQqrBeh/hqBGrdOD4tkn0bLRWJ4esIGMMma2cw8P0Urx4EB8sVr2B9qComulUNo4zI JeJxlW0BzsBnOX0NF6mgCUIe4sQUHoJ1iEIHTDtPPmZk+gIkJo4wdtv2qwsWKQ8etgsd BK0IocAm6GEKLDAnwwwCO5F89vD9aD2HPmQCivusm6nD7lU4YuIJbSzal8kgcJ8YnweU XrUw== X-Gm-Message-State: AMCzsaW63V9qUinVtnfADUgs4XRUf/upJ+tChH0Fe0tp34bQCf4uWE7g VmMWpNGtPMxAm5podXWh/O2epA== X-Google-Smtp-Source: ABhQp+SiBqQbbTk+/3/iuUVjaiX0l6cnrdthG0kVia+s4YnaAE9zkYQgkjSK1NOgMglcHi/Sgw7vUA== X-Received: by 10.80.226.74 with SMTP id o10mr24300669edl.290.1510051713099; Tue, 07 Nov 2017 02:48:33 -0800 (PST) Received: from localhost.localdomain (xd93dd96b.cust.hiper.dk. [217.61.217.107]) by smtp.gmail.com with ESMTPSA id q12sm1044958edj.29.2017.11.07.02.48.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 07 Nov 2017 02:48:32 -0800 (PST) From: Christoffer Dall To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Subject: [PULL 16/26] KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit Date: Tue, 7 Nov 2017 11:47:49 +0100 Message-Id: <20171107104800.30021-17-christoffer.dall@linaro.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171107104800.30021-1-christoffer.dall@linaro.org> References: <20171107104800.30021-1-christoffer.dall@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171107_024849_660941_B811A4FC X-CRM114-Status: GOOD ( 18.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , Christoffer Dall , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Christoffer Dall There is no need to schedule and cancel a hrtimer when entering and exiting the guest, because we know when the physical timer is going to fire when the guest programs it, and we can simply program the hrtimer at that point. Now when the register modifications from the guest go through the kvm_arm_timer_set/get_reg functions, which always call kvm_timer_update_state(), we can simply consider the timer state in this function and schedule and cancel the timers as needed. This avoids looking at the physical timer emulation state when entering and exiting the VCPU, allowing for faster servicing of the VM when needed. Signed-off-by: Christoffer Dall Reviewed-by: Marc Zyngier --- virt/kvm/arm/arch_timer.c | 75 ++++++++++++++++++++++++++++++++--------------- 1 file changed, 51 insertions(+), 24 deletions(-) diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 7f4f12d48a1a..20e56c420632 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -202,7 +202,27 @@ static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt) static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt) { - WARN(1, "Timer only used to ensure guest exit - unexpected event."); + struct arch_timer_context *ptimer; + struct arch_timer_cpu *timer; + struct kvm_vcpu *vcpu; + u64 ns; + + timer = container_of(hrt, struct arch_timer_cpu, phys_timer); + vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu); + ptimer = vcpu_ptimer(vcpu); + + /* + * Check that the timer has really expired from the guest's + * PoV (NTP on the host may have forced it to expire + * early). If not ready, schedule for a later time. + */ + ns = kvm_timer_compute_delta(ptimer); + if (unlikely(ns)) { + hrtimer_forward_now(hrt, ns_to_ktime(ns)); + return HRTIMER_RESTART; + } + + kvm_timer_update_irq(vcpu, true, ptimer); return HRTIMER_NORESTART; } @@ -256,24 +276,28 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, } /* Schedule the background timer for the emulated timer. */ -static void phys_timer_emulate(struct kvm_vcpu *vcpu, - struct arch_timer_context *timer_ctx) +static void phys_timer_emulate(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); - if (kvm_timer_should_fire(timer_ctx)) - return; - - if (!kvm_timer_irq_can_fire(timer_ctx)) + /* + * If the timer can fire now we have just raised the IRQ line and we + * don't need to have a soft timer scheduled for the future. If the + * timer cannot fire at all, then we also don't need a soft timer. + */ + if (kvm_timer_should_fire(ptimer) || !kvm_timer_irq_can_fire(ptimer)) { + soft_timer_cancel(&timer->phys_timer, NULL); return; + } - /* The timer has not yet expired, schedule a background timer */ - soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(timer_ctx)); + soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(ptimer)); } /* - * Check if there was a change in the timer state (should we raise or lower - * the line level to the GIC). + * Check if there was a change in the timer state, so that we should either + * raise or lower the line level to the GIC or schedule a background timer to + * emulate the physical timer. */ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) { @@ -295,6 +319,8 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) if (kvm_timer_should_fire(ptimer) != ptimer->irq.level) kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer); + + phys_timer_emulate(vcpu); } static void vtimer_save_state(struct kvm_vcpu *vcpu) @@ -441,6 +467,9 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu) if (has_vhe()) disable_el1_phys_timer_access(); + + /* Set the background timer for the physical timer emulation. */ + phys_timer_emulate(vcpu); } bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) @@ -476,12 +505,6 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) if (unlikely(!timer->enabled)) return; - - if (kvm_timer_should_fire(ptimer) != ptimer->irq.level) - kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer); - - /* Set the background timer for the physical timer emulation. */ - phys_timer_emulate(vcpu, vcpu_ptimer(vcpu)); } void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) @@ -496,6 +519,17 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) vtimer_save_state(vcpu); + /* + * Cancel the physical timer emulation, because the only case where we + * need it after a vcpu_put is in the context of a sleeping VCPU, and + * in that case we already factor in the deadline for the physical + * timer when scheduling the bg_timer. + * + * In any case, we re-schedule the hrtimer for the physical timer when + * coming back to the VCPU thread in kvm_timer_vcpu_load(). + */ + soft_timer_cancel(&timer->phys_timer, NULL); + /* * The kernel may decide to run userspace after calling vcpu_put, so * we reset cntvoff to 0 to ensure a consistent read between user @@ -538,15 +572,8 @@ static void unmask_vtimer_irq(struct kvm_vcpu *vcpu) */ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) { - struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); - /* - * This is to cancel the background timer for the physical timer - * emulation if it is set. - */ - soft_timer_cancel(&timer->phys_timer, NULL); - /* * If we entered the guest with the vtimer output asserted we have to * check if the guest has modified the timer so that we should lower