From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Rutherford Subject: Re: [PATCH v5 3/4] KVM: x86: Add EOI exit bitmap inference Date: Wed, 29 Jul 2015 23:27:48 -0700 Message-ID: <20150730062748.GA19303@google.com> References: <1438039062-3168-1-git-send-email-srutherford@google.com> <1438039062-3168-3-git-send-email-srutherford@google.com> <55B8C931.5090300@redhat.com> <20150729202714.GA32444@google.com> <55B9C2EF.7020603@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Paolo Bonzini , kvm@vger.kernel.org To: Jan Kiszka Return-path: Received: from mail-pd0-f176.google.com ([209.85.192.176]:35798 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750741AbbG3G1y (ORCPT ); Thu, 30 Jul 2015 02:27:54 -0400 Received: by pdrg1 with SMTP id g1so19039576pdr.2 for ; Wed, 29 Jul 2015 23:27:54 -0700 (PDT) Content-Disposition: inline In-Reply-To: <55B9C2EF.7020603@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Jul 30, 2015 at 08:23:43AM +0200, Jan Kiszka wrote: > On 2015-07-29 22:27, Steve Rutherford wrote: > > On Wed, Jul 29, 2015 at 02:38:09PM +0200, Paolo Bonzini wrote: > >> > >> > >> On 28/07/2015 01:17, Steve Rutherford wrote: > >>> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h > >>> index d8cc54b..f6ce112 100644 > >>> --- a/arch/x86/kvm/ioapic.h > >>> +++ b/arch/x86/kvm/ioapic.h > >>> @@ -9,6 +9,7 @@ struct kvm; > >>> struct kvm_vcpu; > >>> > >>> #define IOAPIC_NUM_PINS KVM_IOAPIC_NUM_PINS > >>> +#define MAX_NR_RESERVED_IOAPIC_PINS 48 > >> > >> Why is this needed? > > This constant is used to bound the number of IOAPIC pins that are > > reservable when enabling KVM_CAP_SPLIT_IRQCHIP. IIRC, x86 doesn't > > support more than 2 IOAPICs. > > Huh? Surely not. I've already seen boxes with at least three, and I > think you can even hot-plug them today via extension cards. Not saying > that QEMU supports that already, even without KVM, but we must not limit > ourselves in the kernel API. > > So please remove such a static limit on how many IOAPICs userspace can > emulate or raise it to something sufficiently large that will last long > enough. I'll go with the latter. I'll set it to the same size as the max size of the GSI routing table, which needs to upper bound it. > > Jan > > -- > Siemens AG, Corporate Technology, CT RTC ITP SES-DE > Corporate Competence Center Embedded Linux