From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42211) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bnNJB-0001Rq-Ur for qemu-devel@nongnu.org; Fri, 23 Sep 2016 06:02:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bnNJ6-0005qH-DF for qemu-devel@nongnu.org; Fri, 23 Sep 2016 06:02:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51886) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bnNJ6-0005q8-7j for qemu-devel@nongnu.org; Fri, 23 Sep 2016 06:02:12 -0400 Date: Fri, 23 Sep 2016 18:02:07 +0800 From: Peter Xu Message-ID: <20160923100207.GD29144@pxdev.xzpeter.org> References: <20160922210432.18680-1-rkrcmar@redhat.com> <20160922210432.18680-6-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 5/5] intel_iommu: do not allow EIM without KVM support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Radim =?utf-8?B?S3LEjW3DocWZ?= , qemu-devel@nongnu.org, Igor Mammedov , Richard Henderson , Eduardo Habkost , "Michael S. Tsirkin" On Fri, Sep 23, 2016 at 11:27:09AM +0200, Paolo Bonzini wrote: > Since the whole IOMMU feature is new and somewhat experimental, I think > it's okay to just make EIM the default for >=2.8 machine types if KVM is > on (using DEFINE_PROP_ON_OFF_AUTO; auto means true if KVM is on and > false otherwise, and pc-2.7 would set eim=off). It means requiring > kernel 4.8 by default, but I don't think it's a big deal. I think the problem is, even we have KVM support for x2apic, we are still losing QEMU part. And guests with cluster x2apic and >8 vcpus will not working properly on device interrupts, which can be very confusing to people (it can boot, but some devices just don't work properly, and they won't see useful information in guest dmesg). Thanks, -- peterx