4 files changed, 75 insertions, 11 deletions

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 6af7cf71d6b2..09a77dbc73c9 100644
--- 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;
diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h
index 336878a5d205..3abb5f5cccc8 100644
--- a/arch/x86/events/intel/pt.h
+++ b/arch/x86/events/intel/pt.h
@@ -65,6 +65,7 @@ enum pt_capabilities {
 struct pt_pmu {
         struct pmu              pmu;
         u32                     caps[PT_CPUID_REGS_NUM * PT_CPUID_LEAVES];
+        bool                    vmx;
 };
 
 /**
@@ -107,10 +108,12 @@ struct pt_buffer {
  * struct pt - per-cpu pt context
  * @handle:     perf output handle
  * @handle_nmi: do handle PT PMI on this cpu, there's an active event
+ * @vmx_on:     1 if VMX is ON on this cpu
  */
 struct pt {
         struct perf_output_handle handle;
         int                     handle_nmi;
+        int                     vmx_on;
 };
 
 #endif /* __INTEL_PT_H__ */
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 5a2ed3ed2f26..f353061bba1d 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -285,6 +285,10 @@ static inline void perf_events_lapic_init(void)	{ }
 static inline void perf_check_microcode(void) { }
 #endif
 
+#ifdef CONFIG_CPU_SUP_INTEL
+ extern void intel_pt_handle_vmx(int on);
+#endif
+
 #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
  extern void amd_pmu_enable_virt(void);
  extern void amd_pmu_disable_virt(void);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ee1c8a93871c..133679d520af 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3103,6 +3103,8 @@ static __init int vmx_disabled_by_bios(void)
 
 static void kvm_cpu_vmxon(u64 addr)
 {
+        intel_pt_handle_vmx(1);
+
         asm volatile (ASM_VMX_VMXON_RAX
                         : : "a"(&addr), "m"(addr)
                         : "memory", "cc");
@@ -3172,6 +3174,8 @@ static void vmclear_local_loaded_vmcss(void)
 static void kvm_cpu_vmxoff(void)
 {
         asm volatile (__ex(ASM_VMX_VMXOFF) : : : "cc");
+
+        intel_pt_handle_vmx(0);
 }
 
 static void hardware_disable(void)