From 2aef6f306b39bbe74e2287d6e2ee07c4867d87d0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 11 Nov 2021 02:07:29 +0000 Subject: [PATCH] perf: Force architectures to opt-in to guest callbacks Introduce GUEST_PERF_EVENTS and require architectures to select it to allow registering and using guest callbacks in perf. This will hopefully make it more difficult for new architectures to add useless "support" for guest callbacks, e.g. via copy+paste. Stubbing out the helpers has the happy bonus of avoiding a load of perf_guest_cbs when GUEST_PERF_EVENTS=n on arm64/x86. Signed-off-by: Sean Christopherson Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paolo Bonzini Link: https://lore.kernel.org/r/20211111020738.2512932-9-seanjc@google.com --- arch/arm64/kvm/Kconfig | 1 + arch/x86/kvm/Kconfig | 1 + arch/x86/xen/Kconfig | 1 + include/linux/perf_event.h | 6 ++++++ init/Kconfig | 4 ++++ kernel/events/core.c | 2 ++ 6 files changed, 15 insertions(+) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 8ffcbe29395e..e9761d84f982 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -39,6 +39,7 @@ menuconfig KVM select HAVE_KVM_IRQ_BYPASS select HAVE_KVM_VCPU_RUN_PID_CHANGE select SCHED_INFO + select GUEST_PERF_EVENTS if PERF_EVENTS help Support hosting virtualized guest machines. diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 619186138176..47bdbe705a76 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -36,6 +36,7 @@ config KVM select KVM_MMIO select SCHED_INFO select PERF_EVENTS + select GUEST_PERF_EVENTS select HAVE_KVM_MSI select HAVE_KVM_CPU_RELAX_INTERCEPT select HAVE_KVM_NO_POLL diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig index 6bcd3d8ca6ac..85246dd9faa1 100644 --- a/arch/x86/xen/Kconfig +++ b/arch/x86/xen/Kconfig @@ -23,6 +23,7 @@ config XEN_PV select PARAVIRT_XXL select XEN_HAVE_PVMMU select XEN_HAVE_VPMU + select GUEST_PERF_EVENTS help Support running as a Xen PV guest. diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 346d5aff5804..ea47ef616ee0 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1242,6 +1242,7 @@ extern void perf_event_bpf_event(struct bpf_prog *prog, enum perf_bpf_event_type type, u16 flags); +#ifdef CONFIG_GUEST_PERF_EVENTS extern struct perf_guest_info_callbacks __rcu *perf_guest_cbs; static inline struct perf_guest_info_callbacks *perf_get_guest_cbs(void) { @@ -1280,6 +1281,11 @@ static inline unsigned int perf_guest_handle_intel_pt_intr(void) } extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs); extern void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs); +#else +static inline unsigned int perf_guest_state(void) { return 0; } +static inline unsigned long perf_guest_get_ip(void) { return 0; } +static inline unsigned int perf_guest_handle_intel_pt_intr(void) { return 0; } +#endif /* CONFIG_GUEST_PERF_EVENTS */ extern void perf_event_exec(void); extern void perf_event_comm(struct task_struct *tsk, bool exec); diff --git a/init/Kconfig b/init/Kconfig index 036b750e8d8a..72d40b3b5805 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1804,6 +1804,10 @@ config HAVE_PERF_EVENTS help See tools/perf/design.txt for details. +config GUEST_PERF_EVENTS + bool + depends on HAVE_PERF_EVENTS + config PERF_USE_VMALLOC bool help diff --git a/kernel/events/core.c b/kernel/events/core.c index 17e5b20762c5..5a3502cd5362 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6521,6 +6521,7 @@ static void perf_pending_event(struct irq_work *entry) perf_swevent_put_recursion_context(rctx); } +#ifdef CONFIG_GUEST_PERF_EVENTS struct perf_guest_info_callbacks __rcu *perf_guest_cbs; void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs) @@ -6541,6 +6542,7 @@ void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs) synchronize_rcu(); } EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks); +#endif static void perf_output_sample_regs(struct perf_output_handle *handle,