KVM: x86: Add requested index to the CPUID tracepoint

Output the requested index when tracing CPUID emulation; it's basically
mandatory for leafs where the index is meaningful, and is helpful for
verifying KVM correctness even when the index isn't meaningful, e.g. the
trace for a Linux guest's hypervisor_cpuid_base() probing appears to
be broken (returns all zeroes) at first glance, but is correct because
the index is non-zero, i.e. the output values correspond to a random
index in the maximum basic leaf.

Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 435a7da07d5f373dacb979e6bd6dede8c1ca91f9..2de721f3c420e873c2a3b4d3f9a506a2000c3e88 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1026,7 +1026,7 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
                        }
                }
        }
-       trace_kvm_cpuid(orig_function, *eax, *ebx, *ecx, *edx, exact);
+       trace_kvm_cpuid(orig_function, index, *eax, *ebx, *ecx, *edx, exact);
        return exact;
 }
 EXPORT_SYMBOL_GPL(kvm_cpuid);

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 6c4d9b4caf0704eb53fb1eda2c7d9c08d875d736..27270ba0f05fd4c42c0e5849371fe9dc682a8a85 100644 (file)
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -151,12 +151,14 @@ TRACE_EVENT(kvm_fast_mmio,
  * Tracepoint for cpuid.
  */
 TRACE_EVENT(kvm_cpuid,
-       TP_PROTO(unsigned int function, unsigned long rax, unsigned long rbx,
-                unsigned long rcx, unsigned long rdx, bool found),
-       TP_ARGS(function, rax, rbx, rcx, rdx, found),
+       TP_PROTO(unsigned int function, unsigned int index, unsigned long rax,
+                unsigned long rbx, unsigned long rcx, unsigned long rdx,
+                bool found),
+       TP_ARGS(function, index, rax, rbx, rcx, rdx, found),
 
        TP_STRUCT__entry(
                __field(        unsigned int,   function        )
+               __field(        unsigned int,   index           )
                __field(        unsigned long,  rax             )
                __field(        unsigned long,  rbx             )
                __field(        unsigned long,  rcx             )
@@ -166,6 +168,7 @@ TRACE_EVENT(kvm_cpuid,
 
        TP_fast_assign(
                __entry->function       = function;
+               __entry->index          = index;
                __entry->rax            = rax;
                __entry->rbx            = rbx;
                __entry->rcx            = rcx;
@@ -173,8 +176,8 @@ TRACE_EVENT(kvm_cpuid,
                __entry->found          = found;
        ),
 
-       TP_printk("func %x rax %lx rbx %lx rcx %lx rdx %lx, cpuid entry %s",
-                 __entry->function, __entry->rax,
+       TP_printk("func %x idx %x rax %lx rbx %lx rcx %lx rdx %lx, cpuid entry %s",
+                 __entry->function, __entry->index, __entry->rax,
                  __entry->rbx, __entry->rcx, __entry->rdx,
                  __entry->found ? "found" : "not found")
 );