kvmexit: Don't use raw tracepoint

The kvm_exit tracepoint has the following proto ([0]):

  TP_PROTO(struct kvm_vcpu *vcpu, u32 isa)

So for raw tracepoint, the first arg is a pointer to kvm_vcpu,
not exit_reason. The exit_reason is hidden inside struct vcpu_vmx
for Intel CPU (or struct vcpu_svm for AMD CPU). Both structs are
not part of the UAPI, so it's hard to extract exit_reason.
Let's always use the kvm_exit tracepoint instead.

  [0]: https://github.com/torvalds/linux/blob/1ef6663a587b/arch/x86/kvm/trace.h#L296

Signed-off-by: Hengqi Chen <[email protected]>

Author: chenhengqi

tools/kvmexit.py

@@ -96,10 +96,10 @@ def valid_args_list(args):
 };
 BPF_PERCPU_ARRAY(pcpu_cache, struct cache_info, 1);
 
-FUNC_ENTRY {
+TRACEPOINT_PROBE(kvm, kvm_exit) {
     int cache_miss = 0;
     int zero = 0;
-    u32 er = GET_ER;
+    u32 er = args->exit_reason;
     if (er >= REASON_NUM) {
         return 0;
     }
@@ -256,19 +256,6 @@ def valid_args_list(args):
 except Exception as e:
     raise Exception("Failed to do precondition check, due to: %s." % e)
 
-try:
-    if BPF.support_raw_tracepoint_in_module():
-        # Let's firstly try raw_tracepoint_in_module
-        func_entry = "RAW_TRACEPOINT_PROBE(kvm_exit)"
-        get_er = "ctx->args[0]"
-    else:
-        # If raw_tp_in_module is not supported, fall back to regular tp
-        func_entry = "TRACEPOINT_PROBE(kvm, kvm_exit)"
-        get_er = "args->exit_reason"
-except Exception as e:
-    raise Exception("Failed to catch kvm exit reasons due to: %s" % e)
-
-
 def find_tid(tgt_dir, tgt_vcpu):
     for tid in os.listdir(tgt_dir):
         path = tgt_dir + "/" + tid + "/comm"
@@ -309,10 +296,6 @@ def find_tid(tgt_dir, tgt_vcpu):
     thread_filter = '0'
     header_format = "PID      TID      "
 bpf_text = bpf_text.replace('THREAD_FILTER', thread_filter)
-
-# For kernel >= 5.0, use RAW_TRACEPOINT_MODULE for performance consideration
-bpf_text = bpf_text.replace('FUNC_ENTRY', func_entry)
-bpf_text = bpf_text.replace('GET_ER', get_er)
 b = BPF(text=bpf_text)