From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [PATCH 5/5] arm/arm64: KVM: Initialize the vgic on-demand when injecting IRQs Date: Wed, 10 Dec 2014 13:45:50 +0100 Message-ID: <5488407E.50506@linaro.org> References: <1418139844-27892-1-git-send-email-christoffer.dall@linaro.org> <1418139844-27892-6-git-send-email-christoffer.dall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Christoffer Dall , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Return-path: Received: from mail-wi0-f174.google.com ([209.85.212.174]:51643 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753999AbaLJMrN (ORCPT ); Wed, 10 Dec 2014 07:47:13 -0500 Received: by mail-wi0-f174.google.com with SMTP id h11so11101150wiw.1 for ; Wed, 10 Dec 2014 04:47:12 -0800 (PST) In-Reply-To: <1418139844-27892-6-git-send-email-christoffer.dall@linaro.org> Sender: kvm-owner@vger.kernel.org List-ID: On 12/09/2014 04:44 PM, Christoffer Dall wrote: > Userspace assumes that it can wire up IRQ injections after having > created all VCPUs and after having created the VGIC, but potentially > before starting the first VCPU. This can currently lead to lost IRQs > because the state of that IRQ injection is not stored anywhere and we > don't return an error to userspace. > > We haven't seen this problem manifest itself yet, Actually we did with VFIO signaling setup before VGIC init! presumably because > guests reset the devices on boot, but this could cause issues with > migration and other non-standard startup configurations. > > Signed-off-by: Christoffer Dall > --- > virt/kvm/arm/vgic.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > index c98cc6b..feef015 100644 > --- a/virt/kvm/arm/vgic.c > +++ b/virt/kvm/arm/vgic.c > @@ -1693,8 +1693,13 @@ out: > int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num, > bool level) > { > - if (likely(vgic_ready(kvm)) && > - vgic_update_irq_pending(kvm, cpuid, irq_num, level)) > + if (unlikely(!vgic_initialized(kvm))) { > + mutex_lock(&kvm->lock); > + vgic_init(kvm); > + mutex_unlock(&kvm->lock); > + } I was previously encouraged to test the virtual interrupt controller readiness when setting irqfd up(proposal made in https://lkml.org/lkml/2014/12/3/601). I guess this becomes useless now, correct? Reviewed-by on the whole series. Eric > + > + if (vgic_update_irq_pending(kvm, cpuid, irq_num, level)) > vgic_kick_vcpus(kvm); > > return 0; >