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perf: Force architectures to opt-in to guest callbacks

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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 <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20211111020738.2512932-9-seanjc@google.com
This commit is contained in:
Sean Christopherson 2021-11-11 02:07:29 +00:00 committed by Peter Zijlstra
parent 1c3430516b
commit 2aef6f306b
6 changed files with 15 additions and 0 deletions
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1
arch/arm64/kvm/Kconfig
View file

@ -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.

1
arch/x86/kvm/Kconfig
View file

@ -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

1
arch/x86/xen/Kconfig
View file

@ -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.

6
include/linux/perf_event.h
View file

@ -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);

4
init/Kconfig
View file

@ -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

2
kernel/events/core.c
View file

@ -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,