[PATCH v2 2/7] perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers

Sean Christopherson
2022-08-03T19:27:11Z

Remove CONFIG_PERF_EVENT=n stubs for functions that are effectively
KVM-only. KVM selects PERF_EVENT and will never consume the stubs.
Dropping the unnecessary stubs will allow simplifying x86_perf_get_lbr()
by getting rid of the impossible-to-hit error path (which KVM doesn't
even check).

Opportunstically reorganize the declarations to collapse multiple
CONFIG_PERF_EVENTS #ifdefs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/perf_event.h | 53 ++++++++-----------------------
1 file changed, 13 insertions(+), 40 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index cc47044401ff..aba196172500 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -509,46 +509,18 @@ extern u64 perf_get_hw_event_config(int hw_event);
extern void perf_check_microcode(void);
extern void perf_clear_dirty_counters(void);
extern int x86_perf_rdpmc_index(struct perf_event *event);
-#else
-static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
-{
- memset(cap, 0, sizeof(*cap));
-}

-static inline u64 perf_get_hw_event_config(int hw_event)
-{
- return 0;
-}
-
-static inline void perf_events_lapic_init(void) { }
-static inline void perf_check_microcode(void) { }
-#endif
-
-#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
+#ifdef CONFIG_CPU_SUP_INTEL
extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data);
extern int x86_perf_get_lbr(struct x86_pmu_lbr *lbr);
-#else
-struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data);
-static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
-{
- return -1;
-}
-#endif
+extern void intel_pt_handle_vmx(int on);
+#endif /* CONFIG_CPU_SUP_INTEL */

-#ifdef CONFIG_CPU_SUP_INTEL
- extern void intel_pt_handle_vmx(int on);
-#else
-static inline void intel_pt_handle_vmx(int on)
-{
+#ifdef CONFIG_CPU_SUP_AMD
+extern void amd_pmu_enable_virt(void);
+extern void amd_pmu_disable_virt(void);

-}
-#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);
-
-#if defined(CONFIG_PERF_EVENTS_AMD_BRS)
+#ifdef CONFIG_PERF_EVENTS_AMD_BRS

#define PERF_NEEDS_LOPWR_CB 1

@@ -566,12 +538,13 @@ static inline void perf_lopwr_cb(bool lopwr_in)
static_call_mod(perf_lopwr_cb)(lopwr_in);
}

-#endif /* PERF_NEEDS_LOPWR_CB */
+#endif /* CONFIG_PERF_EVENTS_AMD_BRS */
+#endif /* CONFIG_CPU_SUP_AMD */

-#else
- static inline void amd_pmu_enable_virt(void) { }
- static inline void amd_pmu_disable_virt(void) { }
-#endif
+#else /* !CONFIG_PERF_EVENTS */
+static inline void perf_events_lapic_init(void) { }
+static inline void perf_check_microcode(void) { }
+#endif /* CONFIG_PERF_EVENTS */

#define arch_perf_out_copy_user copy_from_user_nmi

--
2.37.1.559.g78731f0fdb-goog