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[2001:1868:205::9]) by mx.google.com with ESMTPS id yz2si2660584pbb.143.2015.11.04.06.54.56 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Nov 2015 06:54:56 -0800 (PST) Received-SPF: pass (google.com: domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) client-ip=2001:1868:205::9; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org designates 2001:1868:205::9 as permitted sender) smtp.mailfrom=linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org; dkim=neutral (body hash did not verify) header.i=@linaro_org.20150623.gappssmtp.com Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZtzRf-0005Lo-Ko; Wed, 04 Nov 2015 14:53:51 +0000 Received: from mail-wi0-x230.google.com ([2a00:1450:400c:c05::230]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZtzRC-000571-3p for linux-arm-kernel@lists.infradead.org; Wed, 04 Nov 2015 14:53:24 +0000 Received: by wicll6 with SMTP id ll6so33583388wic.1 for ; Wed, 04 Nov 2015 06:53:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro_org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=e5lRwoWgJt3VWIp0GObc0fXceuRvnPYe7AjfOWNWefc=; b=oLWPflWWOIIXmw+nOfxd3ii0enjJmfY7B3q9QBHBJai7gXv/44DpIcS0J0JKE6LLCX AvifRa+piTcQK+ue4sfzSju/cYSRYUsWygBIfdmktJucb+yu5TqZdIio82TmDWF5ZuT5 avNwXmUj27+YaSp7EYycuB9yjmhYhY0kjlDAkIDECnhra8sYyXc1bgVBoFozZQuUrKHK OV3Rmqu5I7A6xNd0DeExfkK2an6w5V91b4aToCNzgPKbEdWiBsKEa68q1VYygHyqA2Mc Ba7D2cBq5GcbNOznGpw44ShuuYbu3oJDVl6gV+hdqxOy4D7BuCTHyYu2GqjDxOf10rRm WNHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=e5lRwoWgJt3VWIp0GObc0fXceuRvnPYe7AjfOWNWefc=; b=koA5bF3PJ2LaZq5E+SPEVuWgllna3zTzNwwp+CfNm/WBUTtqrwrRexawbkrBQlf54q eFzH6BaicQF4r+oLjn/deN7I358rpyASW+Brutn4iwwl+7D4Vh/waJzTtV6NBn3sFEn+ yeNU0myJ7YAafz7pPgDwOGojvXRMt/BOUp9Tp+VzYrdmNE/oMtm6wGdMtp05ohDi4qnd ykua4/skU1C/8w/US/674MzmSod8YuqDBts9LF/6830lvy14ZiPrT180eI+i4yyhiugH ft889IOC3WKsS5ZGjuIA79g07iNiH+TSQ6d1No3Qccsa3xQVHSDyiJ3T7ERf0+BTP/+d 3Eig== X-Gm-Message-State: ALoCoQnckBqAlne8rm6KX87Vggk4pCQjmlkQHgRPbQUzrBtM/JW/c0KXgwDQAk44Cv8VrzfSG9QH X-Received: by 10.194.179.163 with SMTP id dh3mr2090849wjc.69.1446648780538; Wed, 04 Nov 2015 06:53:00 -0800 (PST) Received: from localhost.localdomain ([94.18.191.146]) by smtp.gmail.com with ESMTPSA id e9sm1985081wjw.8.2015.11.04.06.52.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 04 Nov 2015 06:53:00 -0800 (PST) From: Christoffer Dall To: Paolo Bonzini , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PULL 02/21] arm/arm64: KVM: arch_timer: Only schedule soft timer on vcpu_block Date: Wed, 4 Nov 2015 15:49:41 +0100 Message-Id: <1446648600-27297-3-git-send-email-christoffer.dall@linaro.org> X-Mailer: git-send-email 2.1.2.330.g565301e.dirty In-Reply-To: <1446648600-27297-1-git-send-email-christoffer.dall@linaro.org> References: <1446648600-27297-1-git-send-email-christoffer.dall@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151104_065322_552915_906650D5 X-CRM114-Status: GOOD ( 24.28 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2a00:1450:400c:c05:0:0:0:230 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , Christoffer Dall MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org We currently schedule a soft timer every time we exit the guest if the timer did not expire while running the guest. This is really not necessary, because the only work we do in the timer work function is to kick the vcpu. Kicking the vcpu does two things: (1) If the vpcu thread is on a waitqueue, make it runnable and remove it from the waitqueue. (2) If the vcpu is running on a different physical CPU from the one doing the kick, it sends a reschedule IPI. The second case cannot happen, because the soft timer is only ever scheduled when the vcpu is not running. The first case is only relevant when the vcpu thread is on a waitqueue, which is only the case when the vcpu thread has called kvm_vcpu_block(). Therefore, we only need to make sure a timer is scheduled for kvm_vcpu_block(), which we do by encapsulating all calls to kvm_vcpu_block() with kvm_timer_{un}schedule calls. Additionally, we only schedule a soft timer if the timer is enabled and unmasked, since it is useless otherwise. Note that theoretically userspace can use the SET_ONE_REG interface to change registers that should cause the timer to fire, even if the vcpu is blocked without a scheduled timer, but this case was not supported before this patch and we leave it for future work for now. Signed-off-by: Christoffer Dall --- arch/arm/include/asm/kvm_host.h | 3 -- arch/arm/kvm/arm.c | 10 +++++ arch/arm64/include/asm/kvm_host.h | 3 -- include/kvm/arm_arch_timer.h | 2 + virt/kvm/arm/arch_timer.c | 94 +++++++++++++++++++++++++-------------- 5 files changed, 72 insertions(+), 40 deletions(-) -- 2.1.2.330.g565301e.dirty _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 84da979..c4072d9 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -234,7 +234,4 @@ static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} - #endif /* __ARM_KVM_HOST_H__ */ diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 78b2869..7ed4d47 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -271,6 +271,16 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) return kvm_timer_should_fire(vcpu); } +void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) +{ + kvm_timer_schedule(vcpu); +} + +void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) +{ + kvm_timer_unschedule(vcpu); +} + int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) { /* Force users to call KVM_ARM_VCPU_INIT */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e4f4d65..ed03968 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -255,7 +255,4 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); -static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} - #endif /* __ARM64_KVM_HOST_H__ */ diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index e1e4d7c..ef14cc1 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -71,5 +71,7 @@ u64 kvm_arm_timer_get_reg(struct kvm_vcpu *, u64 regid); int kvm_arm_timer_set_reg(struct kvm_vcpu *, u64 regid, u64 value); bool kvm_timer_should_fire(struct kvm_vcpu *vcpu); +void kvm_timer_schedule(struct kvm_vcpu *vcpu); +void kvm_timer_unschedule(struct kvm_vcpu *vcpu); #endif diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index b9d3a32..32095fb 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -111,14 +111,21 @@ static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt) return HRTIMER_NORESTART; } +static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + + return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) && + (timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) && + !kvm_vgic_get_phys_irq_active(timer->map); +} + bool kvm_timer_should_fire(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; cycle_t cval, now; - if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) || - !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) || - kvm_vgic_get_phys_irq_active(timer->map)) + if (!kvm_timer_irq_can_fire(vcpu)) return false; cval = timer->cntv_cval; @@ -127,12 +134,57 @@ bool kvm_timer_should_fire(struct kvm_vcpu *vcpu) return cval <= now; } +/* + * Schedule the background timer before calling kvm_vcpu_block, so that this + * thread is removed from its waitqueue and made runnable when there's a timer + * interrupt to handle. + */ +void kvm_timer_schedule(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + u64 ns; + cycle_t cval, now; + + BUG_ON(timer_is_armed(timer)); + + /* + * No need to schedule a background timer if the guest timer has + * already expired, because kvm_vcpu_block will return before putting + * the thread to sleep. + */ + if (kvm_timer_should_fire(vcpu)) + return; + + /* + * If the timer is not capable of raising interrupts (disabled or + * masked), then there's no more work for us to do. + */ + if (!kvm_timer_irq_can_fire(vcpu)) + return; + + /* The timer has not yet expired, schedule a background timer */ + cval = timer->cntv_cval; + now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; + + ns = cyclecounter_cyc2ns(timecounter->cc, + cval - now, + timecounter->mask, + &timecounter->frac); + timer_arm(timer, ns); +} + +void kvm_timer_unschedule(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + timer_disarm(timer); +} + /** * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu * @vcpu: The vcpu pointer * - * Disarm any pending soft timers, since the world-switch code will write the - * virtual timer state back to the physical CPU. + * Check if the virtual timer has expired while we were running in the host, + * and inject an interrupt if that was the case. */ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) { @@ -140,17 +192,6 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) bool phys_active; int ret; - /* - * We're about to run this vcpu again, so there is no need to - * keep the background timer running, as we're about to - * populate the CPU timer again. - */ - timer_disarm(timer); - - /* - * If the timer expired while we were not scheduled, now is the time - * to inject it. - */ if (kvm_timer_should_fire(vcpu)) kvm_timer_inject_irq(vcpu); @@ -176,32 +217,17 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) * kvm_timer_sync_hwstate - sync timer state from cpu * @vcpu: The vcpu pointer * - * Check if the virtual timer was armed and either schedule a corresponding - * soft timer or inject directly if already expired. + * Check if the virtual timer has expired while we were running in the guest, + * and inject an interrupt if that was the case. */ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; - cycle_t cval, now; - u64 ns; BUG_ON(timer_is_armed(timer)); - if (kvm_timer_should_fire(vcpu)) { - /* - * Timer has already expired while we were not - * looking. Inject the interrupt and carry on. - */ + if (kvm_timer_should_fire(vcpu)) kvm_timer_inject_irq(vcpu); - return; - } - - cval = timer->cntv_cval; - now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff; - - ns = cyclecounter_cyc2ns(timecounter->cc, cval - now, timecounter->mask, - &timecounter->frac); - timer_arm(timer, ns); } int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,