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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-02-20 15:33:52 +0200
committerIngo Molnar <mingo@kernel.org>2017-03-16 09:51:11 +0100
commitee368428aac96d94a9804b9109a81355451c3cd9 (patch)
treeeb1f0461fa3b32a1f6a187d91129ca1b90cf854b /arch/x86/events
parentae0c2d995d648d5165545d5e05e2869642009b38 (diff)
perf/x86/intel/pt: Handle VMX better
Since commit: 1c5ac21a0e ("perf/x86/intel/pt: Don't die on VMXON") ... PT events depend on re-scheduling to get enabled after a VMX session has taken place. This is, in particular, a problem for CPU context events, which don't normally get re-scheduled, unless there is a reason. This patch changes the VMX handling so that PT event gets re-enabled when VMX root mode exits. Also, notify the user when there's a gap in PT data due to VMX root mode by flagging AUX records as partial. In combination with vmm_exclusive=0 parameter of the kvm_intel driver, this will result in trace gaps only for the duration of the guest's timeslices. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/20170220133352.17995-5-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/events')
-rw-r--r--arch/x86/events/intel/pt.c38
1 files changed, 21 insertions, 17 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 0218728be37a..354e9ff2978c 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -411,6 +411,7 @@ static u64 pt_config_filters(struct perf_event *event)
static void pt_config(struct perf_event *event)
{
+ struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 reg;
if (!event->hw.itrace_started) {
@@ -429,11 +430,15 @@ static void pt_config(struct perf_event *event)
reg |= (event->attr.config & PT_CONFIG_MASK);
event->hw.config = reg;
- wrmsrl(MSR_IA32_RTIT_CTL, reg);
+ if (READ_ONCE(pt->vmx_on))
+ perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_PARTIAL);
+ else
+ wrmsrl(MSR_IA32_RTIT_CTL, reg);
}
static void pt_config_stop(struct perf_event *event)
{
+ struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 ctl = READ_ONCE(event->hw.config);
/* may be already stopped by a PMI */
@@ -441,7 +446,8 @@ static void pt_config_stop(struct perf_event *event)
return;
ctl &= ~RTIT_CTL_TRACEEN;
- wrmsrl(MSR_IA32_RTIT_CTL, ctl);
+ if (!READ_ONCE(pt->vmx_on))
+ wrmsrl(MSR_IA32_RTIT_CTL, ctl);
WRITE_ONCE(event->hw.config, ctl);
@@ -1174,12 +1180,6 @@ void intel_pt_interrupt(void)
if (!READ_ONCE(pt->handle_nmi))
return;
- /*
- * If VMX is on and PT does not support it, don't touch anything.
- */
- if (READ_ONCE(pt->vmx_on))
- return;
-
if (!event)
return;
@@ -1239,12 +1239,19 @@ void intel_pt_handle_vmx(int on)
local_irq_save(flags);
WRITE_ONCE(pt->vmx_on, on);
- if (on) {
- /* prevent pt_config_stop() from writing RTIT_CTL */
- event = pt->handle.event;
- if (event)
- event->hw.config = 0;
- }
+ /*
+ * If an AUX transaction is in progress, it will contain
+ * gap(s), so flag it PARTIAL to inform the user.
+ */
+ event = pt->handle.event;
+ if (event)
+ perf_aux_output_flag(&pt->handle,
+ PERF_AUX_FLAG_PARTIAL);
+
+ /* Turn PTs back on */
+ if (!on && event)
+ wrmsrl(MSR_IA32_RTIT_CTL, event->hw.config);
+
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(intel_pt_handle_vmx);
@@ -1259,9 +1266,6 @@ static void pt_event_start(struct perf_event *event, int mode)
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf;
- if (READ_ONCE(pt->vmx_on))
- return;
-
buf = perf_aux_output_begin(&pt->handle, event);
if (!buf)
goto fail_stop;