From: Peter Zijlstra <peterz@infradead.org>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
James Clark <james.clark@linaro.org>,
Thomas Gleixner <tglx@kernel.org>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Pavel Machek <pavel@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Danilo Krummrich <dakr@kernel.org>,
Johan Hovold <johan@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Jiayuan Chen <jiayuan.chen@linux.dev>,
"Steven Rostedt (Google)" <rostedt@goodmis.org>,
"Vineeth Pillai (Google)" <vineeth@bitbyteword.org>,
Frederic Weisbecker <frederic@kernel.org>,
Andi Kleen <ak@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, driver-core@lists.linux.dev
Subject: Re: [PATCH 3/6] perf/x86/intel/pt: Stop tracing at syscore shutdown
Date: Mon, 2 Nov 2026 11:04:51 +0100 [thread overview]
Message-ID: <20261102100451.GT1779021@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20261102074039.26983-4-adrian.hunter@intel.com>
On Mon, Nov 02, 2026 at 09:40:36AM +0200, Adrian Hunter wrote:
> +static void pt_shutdown_cpu(void *info)
> +{
> + u64 ctl;
> +
> + /*
> + * After VMXON on CPUs without PT support in VMX operation,
> + * TraceEn is already clear and RTIT_CTL must not be written.
> + */
> + rdmsrq(MSR_IA32_RTIT_CTL, ctl);
> + if (ctl & RTIT_CTL_TRACEEN)
> + wrmsrq(MSR_IA32_RTIT_CTL, ctl & ~RTIT_CTL_TRACEEN);
> +}
Why not unconditionally do: wrmsrq(MSR_IA32_RTIT_CTL, 0), at this point?
next prev parent reply other threads:[~2026-11-02 10:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 7:40 [PATCH 0/6] perf/x86/intel/pt: Fix tracing across kexec, kdump and suspend Adrian Hunter
2026-11-02 7:40 ` [PATCH 1/6] irq_work: Re-raise pending irq_work after system resume Adrian Hunter
2026-11-02 9:06 ` Peter Zijlstra
2026-11-02 10:54 ` Adrian Hunter
2026-11-02 16:39 ` Sebastian Andrzej Siewior
2026-11-02 7:40 ` [PATCH 2/6] perf/x86/intel/pt: Stop tracing if VMXON has not yet happened Adrian Hunter
2026-11-02 9:57 ` Peter Zijlstra
2026-11-02 11:04 ` Adrian Hunter
2026-11-02 11:07 ` Peter Zijlstra
2026-11-02 7:40 ` [PATCH 3/6] perf/x86/intel/pt: Stop tracing at syscore shutdown Adrian Hunter
2026-11-02 10:04 ` Peter Zijlstra [this message]
2026-11-02 10:23 ` Adrian Hunter
2026-11-02 11:01 ` Peter Zijlstra
2026-11-02 16:15 ` Andi Kleen
2026-11-02 16:27 ` Adrian Hunter
2026-11-02 7:40 ` [PATCH 4/6] perf/x86/intel/pt: Clear TraceEn in hardware in cpu_emergency_stop_pt() Adrian Hunter
2026-11-02 10:07 ` Peter Zijlstra
2026-11-02 7:40 ` [PATCH 5/6] perf/x86/intel/pt: Reset stale MSR state on CPU start and resume Adrian Hunter
2026-11-02 7:40 ` [PATCH 6/6] perf/x86/intel/pt: Stop tracing across system suspend Adrian Hunter
2026-11-02 10:10 ` [PATCH 0/6] perf/x86/intel/pt: Fix tracing across kexec, kdump and suspend Peter Zijlstra
2026-11-02 12:22 ` Adrian Hunter
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