From patchwork Fri Feb 3 14:56:53 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoffer Dall X-Patchwork-Id: 9554283 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 7A4BE60424 for ; Fri, 3 Feb 2017 14:57:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5FA1127F95 for ; Fri, 3 Feb 2017 14:57:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5314128401; Fri, 3 Feb 2017 14:57:11 +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=-6.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9655327F95 for ; Fri, 3 Feb 2017 14:57:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752383AbdBCO5G (ORCPT ); Fri, 3 Feb 2017 09:57:06 -0500 Received: from mail-wj0-f179.google.com ([209.85.210.179]:36173 "EHLO mail-wj0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751605AbdBCO5E (ORCPT ); Fri, 3 Feb 2017 09:57:04 -0500 Received: by mail-wj0-f179.google.com with SMTP id n2so1645255wjq.3 for ; Fri, 03 Feb 2017 06:57:03 -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=4up2aaiNX2d7/BOQj5kzzhqphqZjjtlcYjR+EhbSvcw=; b=VMMcjIswEpzHby1QsEgeMwcWH26JaJBs9FjbAKetwISEr38HVFsgWiOBSbEXLwZOQC qUgQhHFV1Hx3/JN5TKXWR+KxlArUWdpuk8Ijz6RUO9DZbUKDT5zFUoyNV/4ZtbFf2BRK 35uKjoDmVJ77vsnudEEoSl+5h5hg6kqb7dpaU= 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=4up2aaiNX2d7/BOQj5kzzhqphqZjjtlcYjR+EhbSvcw=; b=mCgKzzo74MmGNWiI5QFeMSK6YT08s9KWO8tl/QVccSNDAIyCQ2/ZFLJxdq3hWBnOKz BjbiJlF5CtaWqxRznTzmQ7+9qVoZEkhTfWb5ybGY0j13IH8mgkup1PvJMjdz7gTvg6E0 y+FDFguoCBcwT6iQqFA0iwXKSFhZrCEJvOQU2eZ6oB/MPG50I4QGKSRTgoivO1e8nUSh 7fY5V3zw98SmQnnVrMg8I4tBtdb4IPS0r7Bmbb0MQtvuxCtw2DWft4poWrEFhaaAbTf5 E+dU3Dca+2+Q2rtIMw5j4Sxh9b48LstNB7tZAIRCQ7r5ZGLcO2pCxzGcPYVQBgpFMhXT ny+A== X-Gm-Message-State: AIkVDXLwKtCXBHsoCYmsxeQrm25YzWD02cXGgXigQQGS8uQragykgNtgeXf4YrwkoyMrmFBg X-Received: by 10.223.151.138 with SMTP id s10mr12573190wrb.65.1486133822520; Fri, 03 Feb 2017 06:57:02 -0800 (PST) Received: from localhost.localdomain ([217.61.220.40]) by smtp.gmail.com with ESMTPSA id n13sm45466469wrn.40.2017.02.03.06.57.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 03 Feb 2017 06:57:01 -0800 (PST) From: Christoffer Dall To: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: kvm@vger.kernel.org, Marc Zyngier , Alexander Graf , Peter Maydell , Pekka Enberg , Christoffer Dall , Christoffer Dall Subject: [PATCH v2 3/5] KVM: arm/arm64: Support arch timers with a userspace gic Date: Fri, 3 Feb 2017 15:56:53 +0100 Message-Id: <20170203145655.15007-4-cdall@linaro.org> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20170203145655.15007-1-cdall@linaro.org> References: <20170203145655.15007-1-cdall@linaro.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If you're running with a userspace gic or other interrupt constroller (that is no vgic in the kernel), then you have so far not been able to use the architected timers, because the output of the architected timers, which are driven inside the kernel, was a kernel-only construct between the arch timer code and the vgic. This patch implements the new KVM_CAP_ARM_USER_IRQ feature, where we use a side channel on the kvm_run structure, run->s.regs.device_irq_level, to always notify userspace of the timer output levels when using a userspace irqchip. This works by ensureing that before we enter the guest, if the timer output level has changed compared to what we last told userspace, we don't enter the guest, but instead return to userspace to notify it of the new level. If we are exiting, because of an MMIO for example, and the level changed at the same time, the value is also updated and userspace can sample the line as it needs. This is nicely achieved simply always updating the timer_irq_level field after the main run loop. Note that the kvm_timer_update_irq trace event is changed to show the host IRQ number for the timer instead of the guest IRQ number, because the kernel no longer know which IRQ userspace wires up the timer signal to. Also note that this patch implements all required functionality but does not yet advertise the capability. Signed-off-by: Alexander Graf Signed-off-by: Christoffer Dall --- arch/arm/kvm/arm.c | 18 +++---- include/kvm/arm_arch_timer.h | 2 + virt/kvm/arm/arch_timer.c | 121 +++++++++++++++++++++++++++++++++++-------- 3 files changed, 110 insertions(+), 31 deletions(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 21c493a..505f928 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -513,13 +513,7 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) return ret; } - /* - * Enable the arch timers only if we have an in-kernel VGIC - * and it has been properly initialized, since we cannot handle - * interrupts from the virtual timer with a userspace gic. - */ - if (irqchip_in_kernel(kvm) && vgic_initialized(kvm)) - ret = kvm_timer_enable(vcpu); + ret = kvm_timer_enable(vcpu); return ret; } @@ -633,9 +627,12 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) local_irq_disable(); /* - * Re-check atomic conditions + * If we have a singal pending, or need to notify a userspace + * irqchip about timer level changes, then we exit (and update + * the timer level state in kvm_timer_update_run below). */ - if (signal_pending(current)) { + if (signal_pending(current) || + kvm_timer_should_notify_user(vcpu)) { ret = -EINTR; run->exit_reason = KVM_EXIT_INTR; } @@ -707,6 +704,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) ret = handle_exit(vcpu, run, ret); } + /* Tell userspace about in-kernel device output levels */ + kvm_timer_update_run(vcpu); + if (vcpu->sigset_active) sigprocmask(SIG_SETMASK, &sigsaved, NULL); return ret; diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index fe797d6..295584f 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -63,6 +63,8 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu, void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu); void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu); void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu); +bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu); +void kvm_timer_update_run(struct kvm_vcpu *vcpu); void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu); u64 kvm_arm_timer_get_reg(struct kvm_vcpu *, u64 regid); diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 5099b30..5dc2167 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -184,6 +184,27 @@ bool kvm_timer_should_fire(struct arch_timer_context *timer_ctx) return cval <= now; } +/* + * Reflect the timer output level into the kvm_run structure + */ +void kvm_timer_update_run(struct kvm_vcpu *vcpu) +{ + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); + struct kvm_sync_regs *regs = &vcpu->run->s.regs; + + if (likely(irqchip_in_kernel(vcpu->kvm))) + return; + + /* Populate the device bitmap with the timer states */ + regs->device_irq_level &= ~(KVM_ARM_DEV_EL1_VTIMER | + KVM_ARM_DEV_EL1_PTIMER); + if (vtimer->irq.level) + regs->device_irq_level |= KVM_ARM_DEV_EL1_VTIMER; + if (ptimer->irq.level) + regs->device_irq_level |= KVM_ARM_DEV_EL1_PTIMER; +} + static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, struct arch_timer_context *timer_ctx) { @@ -194,9 +215,12 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level, trace_kvm_timer_update_irq(vcpu->vcpu_id, timer_ctx->irq.irq, timer_ctx->irq.level); - ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id, timer_ctx->irq.irq, - timer_ctx->irq.level); - WARN_ON(ret); + if (likely(irqchip_in_kernel(vcpu->kvm))) { + ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id, + timer_ctx->irq.irq, + timer_ctx->irq.level); + WARN_ON(ret); + } } /* @@ -215,7 +239,7 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) * because the guest would never see the interrupt. Instead wait * until we call this function from kvm_timer_flush_hwstate. */ - if (!timer->enabled) + if (unlikely(!timer->enabled)) return; if (kvm_timer_should_fire(vtimer) != vtimer->irq.level) @@ -282,27 +306,12 @@ void kvm_timer_unschedule(struct kvm_vcpu *vcpu) timer_disarm(timer); } -/** - * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu - * @vcpu: The vcpu pointer - * - * 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) +static void kvm_timer_flush_hwstate_vgic(struct kvm_vcpu *vcpu) { struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); bool phys_active; int ret; - if (unlikely(!timer->enabled)) - return; - - kvm_timer_update_state(vcpu); - - /* Set the background timer for the physical timer emulation. */ - kvm_timer_emulate(vcpu, vcpu_ptimer(vcpu)); - /* * If we enter the guest with the virtual input level to the VGIC * asserted, then we have already told the VGIC what we need to, and @@ -354,11 +363,72 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) vtimer->active_cleared_last = !phys_active; } +bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu) +{ + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + struct arch_timer_context *ptimer = vcpu_ptimer(vcpu); + struct kvm_sync_regs *sregs = &vcpu->run->s.regs; + bool vlevel, plevel; + + if (likely(irqchip_in_kernel(vcpu->kvm))) + return false; + + vlevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_VTIMER; + plevel = sregs->device_irq_level & KVM_ARM_DEV_EL1_PTIMER; + + return vtimer->irq.level != vlevel || + ptimer->irq.level != plevel; +} + +static void kvm_timer_flush_hwstate_user(struct kvm_vcpu *vcpu) +{ + struct arch_timer_context *vtimer = vcpu_vtimer(vcpu); + + /* + * To prevent continuously exiting from the guest, we mask the + * physical interrupt such that the guest can make forward progress. + * Once we detect the output level being deasserted, we unmask the + * interrupt again so that we exit from the guest when the timer + * fires. + */ + if (vtimer->irq.level) + disable_percpu_irq(host_vtimer_irq); + else + enable_percpu_irq(host_vtimer_irq, 0); +} + +/** + * kvm_timer_flush_hwstate - prepare timers before running the vcpu + * @vcpu: The vcpu pointer + * + * Check if the virtual timer has expired while we were running in the host, + * and inject an interrupt if that was the case, making sure the timer is + * masked or disabled on the host so that we keep executing. Also schedule a + * software timer for the physical timer if it is enabled. + */ +void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) +{ + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; + + if (unlikely(!timer->enabled)) + return; + + kvm_timer_update_state(vcpu); + + /* Set the background timer for the physical timer emulation. */ + kvm_timer_emulate(vcpu, vcpu_ptimer(vcpu)); + + if (unlikely(!irqchip_in_kernel(vcpu->kvm))) + kvm_timer_flush_hwstate_user(vcpu); + else + kvm_timer_flush_hwstate_vgic(vcpu); +} + /** * kvm_timer_sync_hwstate - sync timer state from cpu * @vcpu: The vcpu pointer * - * Check if the virtual timer has expired while we were running in the guest, + * Check if any of the timers have 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) @@ -558,6 +628,13 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) if (timer->enabled) return 0; + /* Without a VGIC we do not map virtual IRQs to physical IRQs */ + if (!irqchip_in_kernel(vcpu->kvm)) + goto no_vgic; + + if (!vgic_initialized(vcpu->kvm)) + return -ENODEV; + /* * Find the physical IRQ number corresponding to the host_vtimer_irq */ @@ -581,8 +658,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu) if (ret) return ret; +no_vgic: timer->enabled = 1; - return 0; }