[PATCH v3 2/6] KVM: x86/mmu: Fix use of enums in trace_fast_page_fault

[David Matlack <dmatlack@google.com>]

Enum values have to be exported to userspace since the formatting is not
done in the kernel. Without doing this perf maps RET_PF_FIXED and
RET_PF_SPURIOUS to 0, which results in incorrect output:

  $ perf record -a -e kvmmmu:fast_page_fault --filter "ret==3" -- ./access_tracking_perf_test
  $ perf script | head -1
   [...] new 610006048d25877 spurious 0 fixed 0  <------ should be 1

Fix this by exporting the enum values to userspace with TRACE_DEFINE_ENUM.

Fixes: c4371c2a682e ("KVM: x86/mmu: Return unique RET_PF_* values if the fault was fixed")
Signed-off-by: David Matlack <dmatlack@google.com>
---
 arch/x86/kvm/mmu/mmu_internal.h | 3 +++
 arch/x86/kvm/mmu/mmutrace.h     | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 35567293c1fd..626cb848dab4 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -140,6 +140,9 @@ void kvm_flush_remote_tlbs_with_address(struct kvm *kvm,
  * RET_PF_INVALID: the spte is invalid, let the real page fault path update it.
  * RET_PF_FIXED: The faulting entry has been fixed.
  * RET_PF_SPURIOUS: The faulting entry was already fixed, e.g. by another vCPU.
+ *
+ * Any names added to this enum should be exported to userspace for use in
+ * tracepoints via TRACE_DEFINE_ENUM() in mmutrace.h
  */
 enum {
 	RET_PF_RETRY = 0,
diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h
index efbad33a0645..2924a4081a19 100644
--- a/arch/x86/kvm/mmu/mmutrace.h
+++ b/arch/x86/kvm/mmu/mmutrace.h
@@ -54,6 +54,12 @@
 	{ PFERR_RSVD_MASK, "RSVD" },	\
 	{ PFERR_FETCH_MASK, "F" }
 
+TRACE_DEFINE_ENUM(RET_PF_RETRY);
+TRACE_DEFINE_ENUM(RET_PF_EMULATE);
+TRACE_DEFINE_ENUM(RET_PF_INVALID);
+TRACE_DEFINE_ENUM(RET_PF_FIXED);
+TRACE_DEFINE_ENUM(RET_PF_SPURIOUS);
+
 /*
  * A pagetable walk has started
  */
-- 
2.32.0.93.g670b81a890-goog