linux-kernel - [PATCH v5 18/19] perf/x86: Provide stubs of KVM helpers for non-Intel CPUs

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Date:   Fri, 20 Dec 2019 20:45:12 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tony Luck <tony.luck@...el.com>,
        Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-edac@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kselftest@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: [PATCH v5 18/19] perf/x86: Provide stubs of KVM helpers for non-Intel CPUs

Provide stubs for perf_guest_get_msrs() and intel_pt_handle_vmx() when
building without support for Intel CPUs, i.e. CPU_SUP_INTEL=n.  Lack of
stubs is not currently a problem as the only user, KVM_INTEL, takes a
dependency on CPU_SUP_INTEL=y.  Provide the stubs for all CPUs so that
KVM_INTEL can be built for any CPU with compatible hardware support,
e.g. Centuar and Zhaoxin CPUs.

Note, the existing stub for perf_guest_get_msrs() is essentially dead
code as KVM selects CONFIG_PERF_EVENTS, i.e. the only user guarantees
the full implementation is built.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/perf_event.h | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index ee26e9215f18..29964b0e1075 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -322,17 +322,10 @@ struct perf_guest_switch_msr {
 	u64 host, guest;
 };
 
-extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
 extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
 extern void perf_check_microcode(void);
 extern int x86_perf_rdpmc_index(struct perf_event *event);
 #else
-static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
-{
-	*nr = 0;
-	return NULL;
-}
-
 static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
 {
 	memset(cap, 0, sizeof(*cap));
@@ -342,8 +335,23 @@ 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)
+extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+#else
+static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
+{
+	*nr = 0;
+	return NULL;
+}
+#endif
+
 #ifdef CONFIG_CPU_SUP_INTEL
  extern void intel_pt_handle_vmx(int on);
+#else
+static inline void intel_pt_handle_vmx(int on)
+{
+
+}
 #endif
 
 #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
-- 
2.24.1