From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753819AbbJFP1w (ORCPT ); Tue, 6 Oct 2015 11:27:52 -0400 Received: from mail-wi0-f173.google.com ([209.85.212.173]:34771 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753116AbbJFP1t (ORCPT ); Tue, 6 Oct 2015 11:27:49 -0400 Subject: Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support To: "Michael S. Tsirkin" References: <1443991398-23761-1-git-send-email-vladz@cloudius-systems.com> <1443991398-23761-3-git-send-email-vladz@cloudius-systems.com> <20151005031159.GB27303@kroah.com> <56123493.9000602@scylladb.com> <20151006173846-mutt-send-email-mst@redhat.com> Cc: Greg KH , Vlad Zolotarov , linux-kernel@vger.kernel.org, hjk@hansjkoch.de, corbet@lwn.net, bruce.richardson@intel.com, avi@cloudius-systems.com, gleb@cloudius-systems.com, stephen@networkplumber.org, alexander.duyck@gmail.com From: Avi Kivity Message-ID: <5613E871.7090404@scylladb.com> Date: Tue, 6 Oct 2015 18:27:45 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151006173846-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/06/2015 05:46 PM, Michael S. Tsirkin wrote: > On Mon, Oct 05, 2015 at 11:28:03AM +0300, Avi Kivity wrote: >> Eventfd is a natural enough representation of an interrupt; both kvm and >> vfio use it, and are also able to share the eventfd, allowing a vfio >> interrupt to generate a kvm interrupt, without userspace intervention, and >> one day without even kernel intervention. > eventfd without kernel intervention sounds unlikely. > > kvm might configure the cpu such that an interrupt will not trigger a > vmexit. eventfd seems like an unlikely interface to do that: with the > eventfd, device triggering it has no info about the interrupt so it > can't send it to the correct VM. https://lwn.net/Articles/650863/