From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [v3 13/26] KVM: Define a new interface kvm_find_dest_vcpu() for
	VT-d PI
Date: Sat, 20 Dec 2014 14:16:55 +0100
Message-ID: <549576C7.4030800@redhat.com>
References: <1418397300-10870-1-git-send-email-feng.wu@intel.com>	<1418397300-10870-14-git-send-email-feng.wu@intel.com>	<A9667DDFB95DB7438FA9D7D576C3D87E0AC048A2@SHSMSX104.ccr.corp.intel.com>	<549307A5.3060305@redhat.com>	<E959C4978C3B6342920538CF579893F00230A5F8@SHSMSX104.ccr.corp.intel.com>	<5494131E.9030505@redhat.com>
	<E959C4978C3B6342920538CF579893F00230D036@SHSMSX104.ccr.corp.intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Cc: "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" <iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	KVM list <kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Eric Auger <eric.auger-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: "Wu, Feng" <feng.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Paolo Bonzini <pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Yang Zhang <yang.z.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"H. Peter Anvin" <hpa-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	"x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" <x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Gleb Natapov <gleb-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org" <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	"joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org" <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>,
	Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Jiang Liu <public-jiang.liu-VuQAYsv1563Yd54FQh9/CA-wOFGN7rlS/M9smdsby/KFg@public.gmane.org>
Return-path: <iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
In-Reply-To: <E959C4978C3B6342920538CF579893F00230D036-0J0gbvR4kTg/UvCtAeCM4rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/iommu>,
	<mailto:iommu-request-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/iommu/>
List-Post: <mailto:iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
List-Help: <mailto:iommu-request-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/iommu>,
	<mailto:iommu-request-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org?subject=subscribe>
Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
List-Id: kvm.vger.kernel.org



On 20/12/2014 00:48, Wu, Feng wrote:
> In my understanding, lowest priority interrupts are always delivered to a
> Single CPU, we need to find the right destination CPU from the cpumask.

Yes, but which CPU however differs every time the interrupt is
delivered.  So the emulation here is a bit poor.  For now, please limit
PI to fixed interrupts.

> Actually, we don't support posting broadcast/multicast interrupts, because
> the interrupt is associated with one Posted-interrupts descriptor, then one
> vCPU.

Understood.

Paolo