From patchwork Mon Nov 20 19:16:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoffer Dall X-Patchwork-Id: 10067099 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 A21C8602B7 for ; Mon, 20 Nov 2017 19:30:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9246128D43 for ; Mon, 20 Nov 2017 19:30:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8738B28D4B; Mon, 20 Nov 2017 19:30:10 +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 3A1E028D43 for ; Mon, 20 Nov 2017 19:30:10 +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=9AetjmYdYdo1NJ7YM6NpbBkA43PFdXR+GOB/5deEbaA=; b=kQ47/XDHSd1bZR/WliulnOsa/w 6EcqqI09iqwNBRBeLzpwqqi0taRAO4/GxPeeZmmlQIxi0Nbbfjt2+u2ogEwx3oqak3T23oyKKD25x +cAobTrHHm1Tptiu8aoFH62RIusQufvPoh57e3IBbqpQCRwjVcnbQv9FTiDSuav/Wm88XLiBheV4W z0QQx+1vxQdc91zifr5F30d4Ker72/WW63lxLAqo/EoiwwFDTpxE965oYzul/76m1bmrvdkP8/1YL gih9a2VhRh+dkjuaaVykXpgu0aLcEBaYwPeM8upE9L9yu+TvtZ41iHdsQiQR5X+uozH/W7Q4gmoDe V6g+TM6g==; 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 1eGrlc-0001X2-4m; Mon, 20 Nov 2017 19:30:04 +0000 Received: from mail-wr0-x242.google.com ([2a00:1450:400c:c0c::242]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1eGrZ7-0007wL-02 for linux-arm-kernel@lists.infradead.org; Mon, 20 Nov 2017 19:17:11 +0000 Received: by mail-wr0-x242.google.com with SMTP id k61so9081519wrc.4 for ; Mon, 20 Nov 2017 11:16:48 -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=s9wYgOffkxMxEE9Mp51Jy5POgiqz8LrNdEULb2XWfXA=; b=QRyFlvQQNQXXrzAUV6LBQLp6Bs2Stj9OfI5yF/cn7B1sjLgNX/jFjSrtj6mfo4fjPP IPqeCcSsoid7cgasFIKxlqw7AC9v7e3r8gTZLazUSLWmNNCJ3KKIIY4Imj0iJBHOHoPa ovkqR3rCIHe7kUhIQYoxT3z39r/SQzimN64Sw= 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=s9wYgOffkxMxEE9Mp51Jy5POgiqz8LrNdEULb2XWfXA=; b=Q2PeOz5ThqmYH5fT3jvocL1Oew4sgnbTrjGVMvpJHcXrBpQwEBOjlsPtjZ2B1dMoaT qNWDP1OnfptNrbHYZ0RHDV+wrccaLW+jATTLDQbPFfF27ysec/H+nP1E/2+iRSg4YUUl Iv88dJ7ANFD10rvCPU8ASBOHpVsfPceuEmuW+93MHJJcDJakLIFrTjx56pneMrCtRvP0 p6wrX2Sbnt74jfbNscsf9pum0ufgIGdZggsGcEplXruyjJx2r1g5I3c6RKJvjvLrIT0M XC3Kl+33g29exoKFWI2PZcHapKereNHd01ED5fGOjvbqiO2B0uHZWkTke8aA++m3Ftmw +cEg== X-Gm-Message-State: AJaThX67puY4pPyked7qd0DItzAkw2Bu7x+u+JizBgpMqESbhOr3eppz XAO2MOCuoJgXrY4QQCY276P67w== X-Google-Smtp-Source: AGs4zMYRvgtFuSbog9NOwO5sqrPNHHhQNMOqHKCC+EQp2gLrIO3dUZwsQDtiNiqpTnydsiieUt2kYA== X-Received: by 10.223.199.70 with SMTP id b6mr3164101wrh.25.1511205407031; Mon, 20 Nov 2017 11:16:47 -0800 (PST) Received: from localhost.localdomain (x50d2404e.cust.hiper.dk. [80.210.64.78]) by smtp.gmail.com with ESMTPSA id f132sm3726885wmf.17.2017.11.20.11.16.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 20 Nov 2017 11:16:46 -0800 (PST) From: Christoffer Dall To: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 2/8] KVM: arm/arm64: Factor out functionality to get vgic mmio requester_vcpu Date: Mon, 20 Nov 2017 20:16:43 +0100 Message-Id: <20171120191649.17290-3-christoffer.dall@linaro.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171120191649.17290-1-christoffer.dall@linaro.org> References: <20171120191649.17290-1-christoffer.dall@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171120_111709_207379_7B6E80BB X-CRM114-Status: GOOD ( 16.05 ) 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 , Eric Auger , Christoffer Dall , kvm@vger.kernel.org, Andre Przywara 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 We are about to distinguish between userspace accesses and mmio traps for a number of the mmio handlers. When the requester vcpu is NULL, it mens we are handling a userspace acccess. Factor out the functionality to get the request vcpu into its own function, mostly so we have a common place to document the semantics of the return value. Also take the chance to move the functionality outside of holding a spinlock and instead explicitly disable and enable preemption. This supports PREEMPT_RT kernels as well. Acked-by: Marc Zyngier Signed-off-by: Christoffer Dall Reviewed-by: Andre Przywara --- virt/kvm/arm/vgic/vgic-mmio.c | 43 +++++++++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 16 deletions(-) diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c index deb51ee16a3d..6113cf850f47 100644 --- a/virt/kvm/arm/vgic/vgic-mmio.c +++ b/virt/kvm/arm/vgic/vgic-mmio.c @@ -122,6 +122,26 @@ unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu, return value; } +/* + * This function will return the VCPU that performed the MMIO access and + * trapped from twithin the VM, and will return NULL if this is a userspace + * access. + * + * We can disable preemption locally around accessing the per-CPU variable + * because even if the current thread is migrated to another CPU, reading the + * per-CPU value later will give us the same value as we update the per-CPU + * variable in the preempt notifier handlers. + */ +static struct kvm_vcpu *vgic_get_mmio_requester_vcpu(void) +{ + struct kvm_vcpu *vcpu; + + preempt_disable(); + vcpu = kvm_arm_get_running_vcpu(); + preempt_enable(); + return vcpu; +} + void vgic_mmio_write_spending(struct kvm_vcpu *vcpu, gpa_t addr, unsigned int len, unsigned long val) @@ -184,24 +204,10 @@ unsigned long vgic_mmio_read_active(struct kvm_vcpu *vcpu, static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq, bool new_active_state) { - struct kvm_vcpu *requester_vcpu; unsigned long flags; - spin_lock_irqsave(&irq->irq_lock, flags); + struct kvm_vcpu *requester_vcpu = vgic_get_mmio_requester_vcpu(); - /* - * The vcpu parameter here can mean multiple things depending on how - * this function is called; when handling a trap from the kernel it - * depends on the GIC version, and these functions are also called as - * part of save/restore from userspace. - * - * Therefore, we have to figure out the requester in a reliable way. - * - * When accessing VGIC state from user space, the requester_vcpu is - * NULL, which is fine, because we guarantee that no VCPUs are running - * when accessing VGIC state from user space so irq->vcpu->cpu is - * always -1. - */ - requester_vcpu = kvm_arm_get_running_vcpu(); + spin_lock_irqsave(&irq->irq_lock, flags); /* * If this virtual IRQ was written into a list register, we @@ -213,6 +219,11 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq, * vgic_change_active_prepare) and still has to sync back this IRQ, * so we release and re-acquire the spin_lock to let the other thread * sync back the IRQ. + * + * When accessing VGIC state from user space, requester_vcpu is + * NULL, which is fine, because we guarantee that no VCPUs are running + * when accessing VGIC state from user space so irq->vcpu->cpu is + * always -1. */ while (irq->vcpu && /* IRQ may have state in an LR somewhere */ irq->vcpu != requester_vcpu && /* Current thread is not the VCPU thread */