From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38847) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XGoiq-00053A-Rt for qemu-devel@nongnu.org; Mon, 11 Aug 2014 08:29:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XGoik-0002HX-UK for qemu-devel@nongnu.org; Mon, 11 Aug 2014 08:29:08 -0400 Received: from cantor2.suse.de ([195.135.220.15]:47735 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XGoik-0002HT-Ng for qemu-devel@nongnu.org; Mon, 11 Aug 2014 08:29:02 -0400 Message-ID: <53E8B70C.8070205@suse.de> Date: Mon, 11 Aug 2014 14:29:00 +0200 From: Alexander Graf MIME-Version: 1.0 References: <1407594349-9291-1-git-send-email-eric.auger@linaro.org> <1407594349-9291-9-git-send-email-eric.auger@linaro.org> <53E88EC4.9040803@suse.de> <53E8B15A.6080703@linaro.org> <53E8B195.5040808@suse.de> <53E8B6C5.5020106@linaro.org> In-Reply-To: <53E8B6C5.5020106@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v5 08/10] hw/intc/arm_gic_kvm: advertise irqfd List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Auger , eric.auger@st.com, christoffer.dall@linaro.org, qemu-devel@nongnu.org, kim.phillips@freescale.com, a.rigo@virtualopensystems.com Cc: peter.maydell@linaro.org, patches@linaro.org, joel.schopp@amd.com, will.deacon@arm.com, stuart.yoder@freescale.com, Bharat.Bhushan@freescale.com, alex.williamson@redhat.com, a.motakis@virtualopensystems.com, kvmarm@lists.cs.columbia.edu On 11.08.14 14:27, Eric Auger wrote: > On 08/11/2014 02:05 PM, Alexander Graf wrote: >> On 11.08.14 14:04, Eric Auger wrote: >>> On 08/11/2014 11:37 AM, Alexander Graf wrote: >>>> On 09.08.14 16:25, Eric Auger wrote: >>>>> set kvm_irqfds_allowed >>>>> >>>>> Signed-off-by: Eric Auger >>>>> --- >>>>> hw/intc/arm_gic_kvm.c | 2 ++ >>>>> 1 file changed, 2 insertions(+) >>>>> >>>>> diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c >>>>> index 5038885..08b7bf9 100644 >>>>> --- a/hw/intc/arm_gic_kvm.c >>>>> +++ b/hw/intc/arm_gic_kvm.c >>>>> @@ -576,6 +576,8 @@ static void kvm_arm_gic_realize(DeviceState *dev, >>>>> Error **errp) >>>>> KVM_DEV_ARM_VGIC_GRP_ADDR, >>>>> KVM_VGIC_V2_ADDR_TYPE_CPU, >>>>> s->dev_fd); >>>>> + >>>>> + kvm_irqfds_allowed = true; >>>> Is this always true? If it is, why not enable it separately while making >>>> vhost-net work for example? >>> Hi Alex, >>> >>> yes I think so. As soon as KVM is enabled, KVM/arm would enable >>> injection though irqfd. Defintively makes sense to test it with >>> vhost-net too. Well a matter of priority ;-) >> More a matter of accuracy. What if you use new QEMU on old KVM which >> does have in-kernel GIC support, but no irqfd support? > Hi Alex, > > VFIO device code also calls kvm_check_extension(kvm_state, > KVM_CAP_IRQFD_RESAMPLE) which would return false if IRQFD is not enabled > in old kernels. But with respect to vhost-net irqfd usage I cannot > comment yet and you may be right ;-) Yeah, please only set it when the kernel exposes that it supports irqfd ;). Alex