From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 4/4] kvm: Implement PEBS virtualization
Date: Thu, 19 Jun 2014 16:39:57 +0200
Message-ID: <53A2F63D.6010704@redhat.com>
References: <1401412327-14810-1-git-send-email-andi@firstfloor.org> <1401412327-14810-5-git-send-email-andi@firstfloor.org> <CAG7+5M2h1_h2fW1KiD-ReXuxDe_EwmBUOJRwjgAvR79sUBxtgA@mail.gmail.com> <20140602195711.GQ25366@two.firstfloor.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Peter Zijlstra <peterz@infradead.org>, gleb@kernel.org,
	Stephane Eranian <eranian@google.com>,
	KVM <kvm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Andi Kleen <ak@linux.intel.com>
To: Andi Kleen <andi@firstfloor.org>,
	Eric Northup <digitaleric@google.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20140602195711.GQ25366@two.firstfloor.org>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

Il 02/06/2014 21:57, Andi Kleen ha scritto:
> > It would be a bigger concern if we expected virtual PMU migration to
> > work, but I think it would be nice to update kvm_pmu_cpuid_update() to
> > notice the presence/absence of the new CPUID bits, and then store that
> > into per-VM kvm_pmu->pebs_allowed rather than relying only on the
> > per-host perf_pebs_virtualization().
>
> I hope at some point it can work. There shouldn't be any problems
> with migrating to the same CPU model, in many cases (same event
> and same PEBS format) it'll likely even work between models or
> gracefully degrade.

The code is there in both kernel and QEMU, it's just very little tested.

Paolo