Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754350AbaLBRuX (ORCPT ); Tue, 2 Dec 2014 12:50:23 -0500 Received: from mail-wg0-f52.google.com ([74.125.82.52]:65088 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754063AbaLBRuV (ORCPT ); Tue, 2 Dec 2014 12:50:21 -0500 MIME-Version: 1.0 In-Reply-To: <1417541251-20761-1-git-send-email-eric.auger@linaro.org> References: <1417541251-20761-1-git-send-email-eric.auger@linaro.org> From: Peter Maydell Date: Tue, 2 Dec 2014 17:50:00 +0000 Message-ID: Subject: Re: [PATCH] KVM: arm/arm64: vgic: add init entry to VGIC KVM device To: Eric Auger Cc: eric.auger@st.com, Christoffer Dall , Marc Zyngier , arm-mail-list , "kvmarm@lists.cs.columbia.edu" , kvm-devel , Alex Williamson , Alexander Graf , "gleb@kernel.org" , Paolo Bonzini , lkml - Kernel Mailing List , Patch Tracking Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2 December 2014 at 17:27, Eric Auger wrote: > Since the advent of dynamic initialization of VGIC, this latter is > initialized very late, on the first vcpu run. This initialization > could be initiated much earlier by the user, as soon as it has > provided the requested dimensioning parameters: > - number of IRQs and number of vCPUs, > - DIST and CPU interface base address. > > One motivation behind being able to initialize the VGIC sooner is > related to the setup of IRQ injection in VFIO use case. The VFIO > signaling, especially when used along with irqfd must be set *after* > vgic initialization to prevent any virtual IRQ injection before > VGIC initialization. If virtual IRQ injection occurs before the VGIC > init, the IRQ cannot be injected and subsequent injection is blocked > due to VFIO completion mechanism (unmask/mask or forward/unforward). This implies that you're potentially injecting virtual IRQs (and changing the state of the VGIC) before we actually start running the VM (ie before userspace calls KVM_RUN). Is that right? It seems odd, but maybe vfio works that way? -- PMM -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/