From patchwork Wed Dec 18 06:26:34 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoffer Dall X-Patchwork-Id: 3367811 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 178149F32E for ; Wed, 18 Dec 2013 06:27:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 3187D203AB for ; Wed, 18 Dec 2013 06:27:24 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2A25C202E9 for ; Wed, 18 Dec 2013 06:27:23 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VtAbD-0001kM-1t; Wed, 18 Dec 2013 06:27:15 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VtAbA-0004DF-JS; Wed, 18 Dec 2013 06:27:12 +0000 Received: from mail-pa0-f45.google.com ([209.85.220.45]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VtAb7-0004Bw-HK for linux-arm-kernel@lists.infradead.org; Wed, 18 Dec 2013 06:27:10 +0000 Received: by mail-pa0-f45.google.com with SMTP id fb1so5529069pad.32 for ; Tue, 17 Dec 2013 22:26:44 -0800 (PST) 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; bh=FMSxN9iHu8TxowipCN9PtGuNAdGHbbDxm02B/Xrpbgc=; b=MPwmExWyF+5hiynfx6ZI6/AYlvcJLsqBHCoFhzY2/4Nju5n+TyAKJ+PxU139CTCCAY 41Zegnky1gFKdRgv+2p9tZY622rgC4dY1pPp2hECCeY73YhdSiUBTfj/N3+YxcfzMg0o sLQ0wew1qzm79nXTrDwR1H9VRY2LsDGaDDbu0XpuHM1TTzAk5Mvwl4JlmF3kaYVDqBfA zGVRa9hnMDg/JclYS4HsBDOnu6HyZTI8eqZBAzuTRBcq9vcUT/GofJEYHo2vYh4Kt2aD 8re5tUHBKncVcw+nfWPHkpjlxbxdcFoGAUlFvEjUo4Ya/peZaVHVym0X1IWKB83Ci3qz 9ucQ== X-Gm-Message-State: ALoCoQnvRmmjdRfUtvYIEsRUc4N7f3zaaOlz7Boz963nFm/sYeqYK5dD8L+rrvXG3GY3eMtB8lA1 X-Received: by 10.66.142.107 with SMTP id rv11mr32165335pab.17.1387348004009; Tue, 17 Dec 2013 22:26:44 -0800 (PST) Received: from localhost.localdomain (c-67-169-181-221.hsd1.ca.comcast.net. [67.169.181.221]) by mx.google.com with ESMTPSA id nw11sm52114931pab.13.2013.12.17.22.26.41 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 17 Dec 2013 22:26:42 -0800 (PST) From: Christoffer Dall To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v2] arm: KVM: Don't return PSCI_INVAL if waitqueue is inactive Date: Tue, 17 Dec 2013 22:26:34 -0800 Message-Id: <1387347994-3415-1-git-send-email-christoffer.dall@linaro.org> X-Mailer: git-send-email 1.8.5 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131218_012709_694015_DC0B75EE X-CRM114-Status: GOOD ( 19.20 ) X-Spam-Score: -0.1 (/) Cc: linaro-kernel@lists.linaro.org, Christoffer Dall , patches@linaro.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current KVM implementation of PSCI returns INVALID_PARAMETERS if the waitqueue for the corresponding CPU is not active. This does not seem correct, since KVM should not care what the specific thread is doing, for example, user space may not have called KVM_RUN on this VCPU yet or the thread may be busy looping to user space because it received a signal; this is really up to the user space implementation. Instead we should check specifically that the CPU is marked as being turned off, regardless of the VCPU thread state, and if it is, we shall simply clear the pause flag on the CPU and wake up the thread if it happens to be blocked for us. Further, the implementation seems to be racy when executing multiple VCPU threads. There really isn't a reasonable user space programming scheme to ensure all secondary CPUs have reached kvm_vcpu_first_run_init before turning on the boot CPU. Therefore, set the pause flag on the vcpu at VCPU init time (which can reasonably be expected to be completed for all CPUs by user space before running any VCPUs) and clear both this flag and the feature (in case the feature can somehow get set again in the future) and ping the waitqueue on turning on a VCPU using PSCI. Reported-by: Peter Maydell Signed-off-by: Christoffer Dall Acked-by: Marc Zyngier --- Changes[v2]: - Use non-atomic version of test_and_clear_bit instead - Check if vcpu is paused and return KVM_PSCI_RET_INVAL if not - Remove unnecessary feature bit clear arch/arm/kvm/arm.c | 30 +++++++++++++++++++----------- arch/arm/kvm/psci.c | 11 ++++++----- 2 files changed, 25 insertions(+), 16 deletions(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 2a700e0..151eb91 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -478,15 +478,6 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) return ret; } - /* - * Handle the "start in power-off" case by calling into the - * PSCI code. - */ - if (test_and_clear_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features)) { - *vcpu_reg(vcpu, 0) = KVM_PSCI_FN_CPU_OFF; - kvm_psci_call(vcpu); - } - return 0; } @@ -700,6 +691,24 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, return -EINVAL; } +static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu, + struct kvm_vcpu_init *init) +{ + int ret; + + ret = kvm_vcpu_set_target(vcpu, init); + if (ret) + return ret; + + /* + * Handle the "start in power-off" case by marking the VCPU as paused. + */ + if (__test_and_clear_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features)) + vcpu->arch.pause = true; + + return 0; +} + long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -713,8 +722,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, if (copy_from_user(&init, argp, sizeof(init))) return -EFAULT; - return kvm_vcpu_set_target(vcpu, &init); - + return kvm_arch_vcpu_ioctl_vcpu_init(vcpu, &init); } case KVM_SET_ONE_REG: case KVM_GET_ONE_REG: { diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index 0881bf1..448f60e 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -54,15 +54,15 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) } } - if (!vcpu) + /* + * Make sure the caller requested a valid CPU and that the CPU is + * turned off. + */ + if (!vcpu || !vcpu->arch.pause) return KVM_PSCI_RET_INVAL; target_pc = *vcpu_reg(source_vcpu, 2); - wq = kvm_arch_vcpu_wq(vcpu); - if (!waitqueue_active(wq)) - return KVM_PSCI_RET_INVAL; - kvm_reset_vcpu(vcpu); /* Gracefully handle Thumb2 entry point */ @@ -79,6 +79,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) vcpu->arch.pause = false; smp_mb(); /* Make sure the above is visible */ + wq = kvm_arch_vcpu_wq(vcpu); wake_up_interruptible(wq); return KVM_PSCI_RET_SUCCESS;