perf: Enhance perf to allow for guest statistic collection from host

Below patch introduces perf_guest_info_callbacks and related
register/unregister functions. Add more PERF_RECORD_MISC_XXX bits
meaning guest kernel and guest user space.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index f6d43dbfd8e742d6f0d0279ac9bf97218c07ff10..254883d0c7e088424ed983154613b4ad889435e1 100644 (file)
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -135,17 +135,10 @@ extern void perf_events_lapic_init(void);
  */
 #define PERF_EFLAGS_EXACT      (1UL << 3)
 
-#define perf_misc_flags(regs)                          \
-({     int misc = 0;                                   \
-       if (user_mode(regs))                            \
-               misc |= PERF_RECORD_MISC_USER;          \
-       else                                            \
-               misc |= PERF_RECORD_MISC_KERNEL;        \
-       if (regs->flags & PERF_EFLAGS_EXACT)            \
-               misc |= PERF_RECORD_MISC_EXACT;         \
-       misc; })
-
-#define perf_instruction_pointer(regs) ((regs)->ip)
+struct pt_regs;
+extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
+extern unsigned long perf_misc_flags(struct pt_regs *regs);
+#define perf_misc_flags(regs)  perf_misc_flags(regs)
 
 #else
 static inline void init_hw_perf_events(void)           { }

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 626154a9f535b28d53140b60e5b360a6a1a0db75..2ea78abf69d9665437f0b5ca058013bc9865ead4 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1720,6 +1720,11 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
 {
        struct perf_callchain_entry *entry;
 
+       if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+               /* TODO: We don't support guest os callchain now */
+               return NULL;
+       }
+
        if (in_nmi())
                entry = &__get_cpu_var(pmc_nmi_entry);
        else
@@ -1743,3 +1748,29 @@ void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int ski
        regs->cs = __KERNEL_CS;
        local_save_flags(regs->flags);
 }
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+       unsigned long ip;
+       if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+               ip = perf_guest_cbs->get_guest_ip();
+       else
+               ip = instruction_pointer(regs);
+       return ip;
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+       int misc = 0;
+       if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+               misc |= perf_guest_cbs->is_user_mode() ?
+                       PERF_RECORD_MISC_GUEST_USER :
+                       PERF_RECORD_MISC_GUEST_KERNEL;
+       } else
+               misc |= user_mode(regs) ? PERF_RECORD_MISC_USER :
+                       PERF_RECORD_MISC_KERNEL;
+       if (regs->flags & PERF_EFLAGS_EXACT)
+               misc |= PERF_RECORD_MISC_EXACT;
+
+       return misc;
+}

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index bf896d0b2e9c76bcadf411a39421dfff63661683..24de5f181a41972e753f8b0bdba11216b6f94c51 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -288,11 +288,13 @@ struct perf_event_mmap_page {
        __u64   data_tail;              /* user-space written tail */
 };
 
-#define PERF_RECORD_MISC_CPUMODE_MASK          (3 << 0)
+#define PERF_RECORD_MISC_CPUMODE_MASK          (7 << 0)
 #define PERF_RECORD_MISC_CPUMODE_UNKNOWN       (0 << 0)
 #define PERF_RECORD_MISC_KERNEL                        (1 << 0)
 #define PERF_RECORD_MISC_USER                  (2 << 0)
 #define PERF_RECORD_MISC_HYPERVISOR            (3 << 0)
+#define PERF_RECORD_MISC_GUEST_KERNEL          (4 << 0)
+#define PERF_RECORD_MISC_GUEST_USER            (5 << 0)
 
 #define PERF_RECORD_MISC_EXACT                 (1 << 14)
 /*
@@ -446,6 +448,12 @@ enum perf_callchain_context {
 # include <asm/perf_event.h>
 #endif
 
+struct perf_guest_info_callbacks {
+       int (*is_in_guest) (void);
+       int (*is_user_mode) (void);
+       unsigned long (*get_guest_ip) (void);
+};
+
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 #include <asm/hw_breakpoint.h>
 #endif
@@ -932,6 +940,12 @@ static inline void perf_event_mmap(struct vm_area_struct *vma)
                __perf_event_mmap(vma);
 }
 
+extern struct perf_guest_info_callbacks *perf_guest_cbs;
+extern int perf_register_guest_info_callbacks(
+               struct perf_guest_info_callbacks *);
+extern int perf_unregister_guest_info_callbacks(
+               struct perf_guest_info_callbacks *);
+
 extern void perf_event_comm(struct task_struct *tsk);
 extern void perf_event_fork(struct task_struct *tsk);
 
@@ -1001,6 +1015,11 @@ perf_sw_event(u32 event_id, u64 nr, int nmi,
 static inline void
 perf_bp_event(struct perf_event *event, void *data)                    { }
 
+static inline int perf_register_guest_info_callbacks
+(struct perf_guest_info_callbacks *) {return 0; }
+static inline int perf_unregister_guest_info_callbacks
+(struct perf_guest_info_callbacks *) {return 0; }
+
 static inline void perf_event_mmap(struct vm_area_struct *vma)         { }
 static inline void perf_event_comm(struct task_struct *tsk)            { }
 static inline void perf_event_fork(struct task_struct *tsk)            { }

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 07b7a435bf03ba84a833690b54e52d62f2a33454..9dbe8cdaf145f2d86143f6254a14572f37a65684 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2797,6 +2797,27 @@ void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int ski
 }
 
 
+/*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+       perf_guest_cbs = cbs;
+       return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+       perf_guest_cbs = NULL;
+       return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
 /*
  * Output
  */
@@ -3749,7 +3770,7 @@ void __perf_event_mmap(struct vm_area_struct *vma)
                .event_id  = {
                        .header = {
                                .type = PERF_RECORD_MMAP,
-                               .misc = 0,
+                               .misc = PERF_RECORD_MISC_USER,
                                /* .size */
                        },
                        /* .pid */