From: Andi Kleen <andi@firstfloor.org>
To: Gleb Natapov <gleb@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>, Andi Kleen <andi@firstfloor.org>,
peterz@infradead.org, pbonzini@redhat.com, eranian@google.com,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
mtosatti@redhat.com
Subject: Re: [PATCH 4/4] kvm: Implement PEBS virtualization
Date: Mon, 2 Jun 2014 18:52:31 +0200 [thread overview]
Message-ID: <20140602165231.GP25366@two.firstfloor.org> (raw)
In-Reply-To: <20140602164534.GD4715@minantech.com>
BTW I found some more problems in the v1 version.
> > > With EPT it is less likely to happen (but still possible IIRC depending on memory
> > > pressure and how much memory shadow paging code is allowed to use), without EPT
> > > it will happen for sure.
> >
> > Don't care about the non EPT case, this is white listed only for EPT supporting
> > CPUs.
> User may still disable EPT during module load, so pebs should be dropped
> from a guest's cpuid in this case.
Ok.
>
> >
> > > There is nothing, as far as I can see, that says what will happen if the
> > > condition is not met. I always interpreted it as undefined behaviour so
> > > anything can happen including CPU dies completely. You are saying above
> > > on one hand that CPU cannot handle any kinds of faults during write to
> > > DS area, but on the other hand a guest could only crash itself. Is this
> > > architecturally guarantied?
> >
> > You essentially would get random page faults, and the PEBS event will
> > be cancelled. No hangs.
> Is this a guest who will get those random page faults or a host?
The guest (on the white listed CPU models)
-Andi
next prev parent reply other threads:[~2014-06-02 16:52 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-30 1:12 Implement PEBS virtualization for Silvermont Andi Kleen
2014-05-30 1:12 ` [PATCH 1/4] perf: Add PEBS virtualization enable " Andi Kleen
2014-05-30 1:12 ` [PATCH 2/4] perf: Allow guest PEBS for KVM owned counters Andi Kleen
2014-05-30 7:31 ` Peter Zijlstra
2014-05-30 16:03 ` Andi Kleen
2014-05-30 16:17 ` Peter Zijlstra
2014-05-30 1:12 ` [PATCH 3/4] perf: Handle guest PEBS events with a fake event Andi Kleen
2014-05-30 7:34 ` Peter Zijlstra
2014-05-30 16:29 ` Andi Kleen
2014-05-30 1:12 ` [PATCH 4/4] kvm: Implement PEBS virtualization Andi Kleen
2014-05-30 8:21 ` Gleb Natapov
2014-05-30 16:24 ` Andi Kleen
2014-06-02 16:45 ` Gleb Natapov
2014-06-02 16:52 ` Andi Kleen [this message]
2014-06-02 19:09 ` Marcelo Tosatti
2014-06-02 19:05 ` Eric Northup
2014-06-02 19:57 ` Andi Kleen
2014-06-19 14:39 ` Paolo Bonzini
2014-06-10 18:04 ` Marcelo Tosatti
2014-06-10 19:22 ` Andi Kleen
2014-06-10 21:06 ` Marcelo Tosatti
2014-06-19 14:42 ` Paolo Bonzini
2014-06-19 17:33 ` Andi Kleen
2014-06-19 20:33 ` Paolo Bonzini
2014-06-22 13:57 ` Avi Kivity
2014-06-22 19:02 ` Andi Kleen
2014-06-24 16:45 ` Marcelo Tosatti
2014-06-25 7:04 ` Avi Kivity
2014-05-30 7:39 ` Implement PEBS virtualization for Silvermont Peter Zijlstra
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