On Wed, Jan 30, 2019 at 06:02:27PM +0100, Paolo Bonzini wrote:
> On 19/01/19 21:04, Luwei Kang wrote:
> > static struct pt_pmu pt_pmu;
> >
> > @@ -1260,6 +1262,14 @@ void intel_pt_interrupt(void)
> > struct pt_buffer *buf;
> > struct perf_event *event = pt->handle.event;
> >
> > + if (pt->vcpu) {
> > + /* Inject PMI to Guest */
> > + kvm_make_request(KVM_REQ_PMI, pt->vcpu);
> > + __set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT,
> > + (unsigned long *)&pt->vcpu->arch.pmu.global_status);
> > + return;
> > + }
> > +
>
> There is no need to touch struct pt and to know details of KVM in
> arch/x86/events. Please add a function pointer
>
> void (*kvm_handle_pt_interrupt)(void);
>
> to some header, and in handle_pmi_common do
>
> if (unlikely(kvm_handle_intel_pt_interrupt))
> kvm_handle_intel_pt_interrupt();
> else
> intel_pt_interrupt();
>
> The function pointer can be assigned in
> kvm_before_interrupt/kvm_after_interrupt just like you do now.
>
> This should be a simpler patch too.
I know we do this in other places too; but it really is a very bad
pattern.
Exported function pointers are a fscking disaster waiting to happen.
There is nothing that limits access to kvm.o, any random module can try
and poke at it.
How about we extend perf_guest_info_callback with an arch section and
add:
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5aeb4c74fb99..76ce804e72c1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5835,6 +5835,9 @@ struct perf_guest_info_callbacks *perf_guest_cbs;
int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
+ if (WARN_ON_ONCE(perf_guest_cbs))
+ return -EBUSY;
+
perf_guest_cbs = cbs;
return 0;
}
@@ -5842,6 +5845,9 @@ EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
{
+ if (WARN_ON_ONCE(perf_guest_cbs != cbs))
+ return -EINVAL;
+
perf_guest_cbs = NULL;
return 0;
}
