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Date: Thu, 26 Aug 2021 17:57:17 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Marc Zyngier <maz@...nel.org>, Guo Ren <guoren@...nel.org>,
Nick Hu <nickhu@...estech.com>,
Greentime Hu <green.hu@...il.com>,
Vincent Chen <deanbo422@...il.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>, x86@...nel.org,
Paolo Bonzini <pbonzini@...hat.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
"H. Peter Anvin" <hpa@...or.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Stefano Stabellini <sstabellini@...nel.org>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
linux-csky@...r.kernel.org, linux-riscv@...ts.infradead.org,
kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
Artem Kashkanov <artem.kashkanov@...el.com>,
Like Xu <like.xu.linux@...il.com>,
Zhu Lingshan <lingshan.zhu@...el.com>
Subject: [PATCH 14/15] perf: Disallow bulk unregistering of guest callbacks
and do cleanup
Drop the helper that allows bulk unregistering of the per-CPU callbacks
now that KVM, the only entity that actually unregisters callbacks, uses
the per-CPU helpers. Bulk unregistering is inherently unsafe as there
are no protections against nullifying a pointer for a CPU that is using
said pointer in a PMI handler.
Opportunistically tweak names to better reflect reality.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
arch/x86/xen/pmu.c | 2 +-
include/linux/kvm_host.h | 2 +-
include/linux/perf_event.h | 9 +++------
kernel/events/core.c | 31 +++++++++++--------------------
virt/kvm/kvm_main.c | 2 +-
5 files changed, 17 insertions(+), 29 deletions(-)
diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index e13b0b49fcdf..57834de043c3 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -548,7 +548,7 @@ void xen_pmu_init(int cpu)
per_cpu(xenpmu_shared, cpu).flags = 0;
if (cpu == 0) {
- perf_register_guest_info_callbacks(&xen_guest_cbs);
+ perf_register_guest_info_callbacks_all_cpus(&xen_guest_cbs);
xen_pmu_arch_init();
}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0db9af0b628c..d68a49d5fc53 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1171,7 +1171,7 @@ unsigned long kvm_arch_vcpu_get_ip(struct kvm_vcpu *vcpu);
void kvm_register_perf_callbacks(void);
static inline void kvm_unregister_perf_callbacks(void)
{
- __perf_unregister_guest_info_callbacks();
+ perf_unregister_guest_info_callbacks();
}
#endif
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7a367bf1b78d..db701409a62f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1238,10 +1238,9 @@ extern void perf_event_bpf_event(struct bpf_prog *prog,
#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
DECLARE_PER_CPU(struct perf_guest_info_callbacks *, perf_guest_cbs);
-extern void __perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
-extern void __perf_unregister_guest_info_callbacks(void);
-extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
+extern void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs);
extern void perf_unregister_guest_info_callbacks(void);
+extern void perf_register_guest_info_callbacks_all_cpus(struct perf_guest_info_callbacks *cbs);
#endif /* CONFIG_HAVE_GUEST_PERF_EVENTS */
extern void perf_event_exec(void);
@@ -1486,9 +1485,7 @@ static inline void
perf_bp_event(struct perf_event *event, void *data) { }
#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
-static inline void perf_register_guest_info_callbacks
-(struct perf_guest_info_callbacks *callbacks) { }
-static inline void perf_unregister_guest_info_callbacks(void) { }
+extern void perf_register_guest_info_callbacks_all_cpus(struct perf_guest_info_callbacks *cbs);
#endif
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2f28d9d8dc94..f1964096c4c2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6485,35 +6485,26 @@ static void perf_pending_event(struct irq_work *entry)
#ifdef CONFIG_HAVE_GUEST_PERF_EVENTS
DEFINE_PER_CPU(struct perf_guest_info_callbacks *, perf_guest_cbs);
-void __perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
-{
- __this_cpu_write(perf_guest_cbs, cbs);
-}
-EXPORT_SYMBOL_GPL(__perf_register_guest_info_callbacks);
-
-void __perf_unregister_guest_info_callbacks(void)
-{
- __this_cpu_write(perf_guest_cbs, NULL);
-}
-EXPORT_SYMBOL_GPL(__perf_unregister_guest_info_callbacks);
-
void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
- int cpu;
-
- for_each_possible_cpu(cpu)
- per_cpu(perf_guest_cbs, cpu) = cbs;
+ __this_cpu_write(perf_guest_cbs, cbs);
}
EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
void perf_unregister_guest_info_callbacks(void)
{
- int cpu;
-
- for_each_possible_cpu(cpu)
- per_cpu(perf_guest_cbs, cpu) = NULL;
+ __this_cpu_write(perf_guest_cbs, NULL);
}
EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+void perf_register_guest_info_callbacks_all_cpus(struct perf_guest_info_callbacks *cbs)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ per_cpu(perf_guest_cbs, cpu) = cbs;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks_all_cpus);
#endif
static void
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e0b1c9386926..1bcc3eab510b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5502,7 +5502,7 @@ EXPORT_SYMBOL_GPL(kvm_set_intel_pt_intr_handler);
void kvm_register_perf_callbacks(void)
{
- __perf_register_guest_info_callbacks(&kvm_guest_cbs);
+ perf_register_guest_info_callbacks(&kvm_guest_cbs);
}
EXPORT_SYMBOL_GPL(kvm_register_perf_callbacks);
#endif
--
2.33.0.259.gc128427fd7-goog
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