Messages in this thread | | | Date | Thu, 22 Sep 2022 13:14:13 +0800 | Subject | Re: [RFC PATCH v2 2/3] perf/x86/intel/pt: Introduce and export pt_get_curr_event() | From | Xiaoyao Li <> |
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On 9/22/2022 12:45 AM, Xiaoyao Li wrote: > KVM supports PT_MODE_HOST_GUEST mode for Intel PT where host and guest > have separate Intel PT configurations and they work independently. > > Currently, in this mode, when both host and guest enable PT, KVM manually > clears MSR_IA32_RTIT_CTL.TRACEEN to disable host PT so that it can > context switch the other PT MSRs. However, PT PMI can be delivered after > this point and before the VM-entry. As a result, the re-enabling of PT > leads to VM-entry failure of guest. > > To solve the problem, introduce and export pt_get_curr_event() for KVM > to get current pt event. Along with perf_event_{dis, en}able_local(), > With them, KVM can avoid PT re-enabling in PT PMI handler. > > Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com> > --- > arch/x86/events/intel/pt.c | 8 ++++++++ > arch/x86/include/asm/perf_event.h | 2 ++ > 2 files changed, 10 insertions(+) > > diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c > index 82ef87e9a897..62bfc45c11c9 100644 > --- a/arch/x86/events/intel/pt.c > +++ b/arch/x86/events/intel/pt.c > @@ -1624,6 +1624,14 @@ static void pt_event_stop(struct perf_event *event, int mode) > } > } > > +struct perf_event *pt_get_curr_event(void) > +{ > + struct pt *pt = this_cpu_ptr(&pt_ctx); > + > + return pt->handle.event; > +} > +EXPORT_SYMBOL_GPL(pt_get_curr_event); > + > static long pt_event_snapshot_aux(struct perf_event *event, > struct perf_output_handle *handle, > unsigned long size) > diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h > index f6fc8dd51ef4..7c3533392cf5 100644 > --- a/arch/x86/include/asm/perf_event.h > +++ b/arch/x86/include/asm/perf_event.h > @@ -553,11 +553,13 @@ static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr) > > #ifdef CONFIG_CPU_SUP_INTEL > extern void intel_pt_handle_vmx(int on); > + extern struct perf_event *pt_get_curr_event(void); > #else > static inline void intel_pt_handle_vmx(int on) > { > > } > +struct perf_event *pt_get_curr_event(void) { return NULL; }
My fault, this needs to be
static inline ...
> #endif > > #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
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