Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm...

[deliverable/linux.git] / arch / x86 / events / intel / pt.c

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 6af7cf71d6b2e8dde7eb042ab3930d557f298efe..09a77dbc73c93110a40d2afbf2dedc86e50ea44f 100644 (file)
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -136,9 +136,21 @@ static int __init pt_pmu_hw_init(void)
        struct dev_ext_attribute *de_attrs;
        struct attribute **attrs;
        size_t size;
+       u64 reg;
        int ret;
        long i;
 
+       if (boot_cpu_has(X86_FEATURE_VMX)) {
+               /*
+                * Intel SDM, 36.5 "Tracing post-VMXON" says that
+                * "IA32_VMX_MISC[bit 14]" being 1 means PT can trace
+                * post-VMXON.
+                */
+               rdmsrl(MSR_IA32_VMX_MISC, reg);
+               if (reg & BIT(14))
+                       pt_pmu.vmx = true;
+       }
+
        attrs = NULL;
 
        for (i = 0; i < PT_CPUID_LEAVES; i++) {
@@ -269,20 +281,23 @@ 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);
 }
 
-static void pt_config_start(bool start)
+static void pt_config_stop(struct perf_event *event)
 {
-       u64 ctl;
+       u64 ctl = READ_ONCE(event->hw.config);
+
+       /* may be already stopped by a PMI */
+       if (!(ctl & RTIT_CTL_TRACEEN))
+               return;
 
-       rdmsrl(MSR_IA32_RTIT_CTL, ctl);
-       if (start)
-               ctl |= RTIT_CTL_TRACEEN;
-       else
-               ctl &= ~RTIT_CTL_TRACEEN;
+       ctl &= ~RTIT_CTL_TRACEEN;
        wrmsrl(MSR_IA32_RTIT_CTL, ctl);
 
+       WRITE_ONCE(event->hw.config, ctl);
+
        /*
         * A wrmsr that disables trace generation serializes other PT
         * registers and causes all data packets to be written to memory,
@@ -291,8 +306,7 @@ static void pt_config_start(bool start)
         * The below WMB, separating data store and aux_head store matches
         * the consumer's RMB that separates aux_head load and data load.
         */
-       if (!start)
-               wmb();
+       wmb();
 }
 
 static void pt_config_buffer(void *buf, unsigned int topa_idx,
@@ -942,11 +956,17 @@ void intel_pt_interrupt(void)
        if (!ACCESS_ONCE(pt->handle_nmi))
                return;
 
-       pt_config_start(false);
+       /*
+        * If VMX is on and PT does not support it, don't touch anything.
+        */
+       if (READ_ONCE(pt->vmx_on))
+               return;
 
        if (!event)
                return;
 
+       pt_config_stop(event);
+
        buf = perf_get_aux(&pt->handle);
        if (!buf)
                return;
@@ -983,6 +1003,35 @@ void intel_pt_interrupt(void)
        }
 }
 
+void intel_pt_handle_vmx(int on)
+{
+       struct pt *pt = this_cpu_ptr(&pt_ctx);
+       struct perf_event *event;
+       unsigned long flags;
+
+       /* PT plays nice with VMX, do nothing */
+       if (pt_pmu.vmx)
+               return;
+
+       /*
+        * VMXON will clear RTIT_CTL.TraceEn; we need to make
+        * sure to not try to set it while VMX is on. Disable
+        * interrupts to avoid racing with pmu callbacks;
+        * concurrent PMI should be handled fine.
+        */
+       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;
+       }
+       local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(intel_pt_handle_vmx);
+
 /*
  * PMU callbacks
  */
@@ -992,6 +1041,9 @@ static void pt_event_start(struct perf_event *event, int mode)
        struct pt *pt = this_cpu_ptr(&pt_ctx);
        struct pt_buffer *buf = perf_get_aux(&pt->handle);
 
+       if (READ_ONCE(pt->vmx_on))
+               return;
+
        if (!buf || pt_buffer_is_full(buf, pt)) {
                event->hw.state = PERF_HES_STOPPED;
                return;
@@ -1014,7 +1066,8 @@ static void pt_event_stop(struct perf_event *event, int mode)
         * see comment in intel_pt_interrupt().
         */
        ACCESS_ONCE(pt->handle_nmi) = 0;
-       pt_config_start(false);
+
+       pt_config_stop(event);
 
        if (event->hw.state == PERF_HES_STOPPED)
                return;