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Peter Anvin" , "Rafael J. Wysocki" , Pavel Machek , Greg Kroah-Hartman , Danilo Krummrich , Johan Hovold , Sebastian Andrzej Siewior , Mathieu Desnoyers , Jiayuan Chen , "Steven Rostedt (Google)" , "Vineeth Pillai (Google)" , Frederic Weisbecker , Andi Kleen , 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 Message-ID: <20261102100451.GT1779021@noisy.programming.kicks-ass.net> References: <20261102074039.26983-1-adrian.hunter@intel.com> <20261102074039.26983-4-adrian.hunter@intel.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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?