From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, vince@deater.net,
eranian@google.com, Arnaldo Carvalho de Melo <acme@infradead.org>,
Borislav Petkov <bp@suse.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on
Date: Tue, 14 Feb 2017 15:02:20 +0100 [thread overview]
Message-ID: <20170214140220.GO6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20170214132416.26400-3-alexander.shishkin@linux.intel.com>
On Tue, Feb 14, 2017 at 03:24:16PM +0200, Alexander Shishkin wrote:
> On systems where PT does not coexist with VMX, users get confused when
> PT turns up with no data because they forgot they're running a kvm
> session at the same time.
>
> This patch adds a preemptive check for any active VMX operations that
> will fail event creation. This does not provide any guarantees or
> protection against racing with a kvm starting in parallel, but is
> intended to serve as a hint for the user. If VMXON happens after an
> event had been created, the event will still produce an empty trace.
>
Would it not be more sensible to write fake PT packets in
intel_pt_handle_vmx() to demarcate VMX regions in the trace?
next prev parent reply other threads:[~2017-02-14 14:03 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 13:24 [PATCH 0/2] perf/x86/intel/pt: VMX related updates Alexander Shishkin
2017-02-14 13:24 ` [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin
2017-02-14 13:56 ` Peter Zijlstra
2017-02-14 16:17 ` Alexander Shishkin
2017-02-14 16:27 ` Peter Zijlstra
2017-02-14 17:21 ` Alexander Shishkin
2017-02-14 18:38 ` Peter Zijlstra
2017-02-14 19:48 ` Peter Zijlstra
2017-02-15 8:11 ` Alexander Shishkin
2017-02-15 8:53 ` Peter Zijlstra
2017-02-14 13:24 ` [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin
2017-02-14 14:02 ` Peter Zijlstra [this message]
2017-02-14 17:47 ` Arnaldo Carvalho de Melo
2017-02-15 8:34 ` Alexander Shishkin
2017-02-15 8:56 ` Peter Zijlstra
2017-02-15 13:05 ` Alexander Shishkin
2017-02-15 13:12 ` Arnaldo Carvalho de Melo
2017-02-15 13:37 ` Peter Zijlstra
2017-02-15 12:51 ` Arnaldo Carvalho de Melo
2017-02-15 13:09 ` Alexander Shishkin
2017-02-15 13:16 ` Arnaldo Carvalho de Melo
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