diff options
| author | Sean Christopherson <seanjc@google.com> | 2022-10-06 00:03:07 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-11-09 12:31:11 -0500 |
| commit | 0b9ca98b722969660ad98b39f766a561ccb39f5f (patch) | |
| tree | 8124d277785370e6c261066f94dfb63633abebd7 /arch/x86/include/asm/perf_event.h | |
| parent | d72cf8ffe460824fdc97f0a9295a2c4e0231a562 (diff) | |
perf/x86/core: Zero @lbr instead of returning -1 in x86_perf_get_lbr() stub
Drop the return value from x86_perf_get_lbr() and have the stub zero out
the @lbr structure instead of returning -1 to indicate "no LBR support".
KVM doesn't actually check the return value, and instead subtly relies on
zeroing the number of LBRs in intel_pmu_init().
Formalize "nr=0 means unsupported" so that KVM doesn't need to add a
pointless check on the return value to fix KVM's benign bug.
Note, the stub is necessary even though KVM x86 selects PERF_EVENTS and
the caller exists only when CONFIG_KVM_INTEL=y. Despite the name,
KVM_INTEL doesn't strictly require CPU_SUP_INTEL, it can be built with
any of INTEL || CENTAUR || ZHAOXIN CPUs.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221006000314.73240-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include/asm/perf_event.h')
| -rw-r--r-- | arch/x86/include/asm/perf_event.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h index 9ac46dbe57d4..5d0f6891ae61 100644 --- a/arch/x86/include/asm/perf_event.h +++ b/arch/x86/include/asm/perf_event.h @@ -543,12 +543,12 @@ static inline void perf_check_microcode(void) { } #if defined(CONFIG_PERF_EVENTS) && defined(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); +extern void 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) +static inline void x86_perf_get_lbr(struct x86_pmu_lbr *lbr) { - return -1; + memset(lbr, 0, sizeof(*lbr)); } #endif |