From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [RFC PATCH 3/4] KVM: x86: Add EOI exit bitmap inference Date: Wed, 13 May 2015 11:24:19 +0200 Message-ID: <55531843.9090304@redhat.com> References: <1431481652-27268-1-git-send-email-srutherford@google.com> <1431481652-27268-3-git-send-email-srutherford@google.com> <5552EB35.2070806@siemens.com> <555305A5.8060601@redhat.com> <55530702.5000407@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Cc: ahonig@google.com To: Jan Kiszka , Steve Rutherford , kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53384 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932439AbbEMJYc (ORCPT ); Wed, 13 May 2015 05:24:32 -0400 In-Reply-To: <55530702.5000407@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 13/05/2015 10:10, Jan Kiszka wrote: >>> >> There can even be multiple IOAPICs (thanks to your patches overcoming >>> >> the single in-kernel instance). >> > >> > With multiple IOAPICs you have more than 24 GSIs per IOAPIC. That means > I don't think that the number of pins per IOAPIC increases. At least not > in the devices I've seen so far. Sorry, that was supposed to be "more than 24 GSIs for the IOAPICs". >> > that the above loop is broken for multiple IOAPICs. > The worst case remains #IOAPIC * 24 iterations - if we have means to > stop after the IOAPIC entries, not iterating over all routes. Yes. Which is not too bad if VCPUs can process it in parallel. >> > But perhaps when enabling KVM_SPLIT_IRQCHIP we can use args[0] to pass >> > the number of IOAPIC routes that will cause EOI exits? > And you need to ensure that their routes can be found in the table > directly. Given IOAPIC hotplug, that may not be the first ones there... Can you reserve a bunch of GSIs at the beginning of the GSI space, and use rt->map[] to access them and build the EOI exit bitmap? Paolo