kvm_vmexit_slower python syntax error

[hrgstephen]

Hi, I encounterd two problems

linux kernel is 4.9
Python 2.7.5 (default, Sep 5 2018, 11:36:03)

problem1:

$sudo ./kvm_vmexit_slower.py
bpf: Failed to load program: Permission denied
0: (bf) r6 = r1
1: (85) call 14
2: (7b) *(u64 *)(r10 -8) = r0
3: (18) r1 = 0xffff886792397b00
5: (bf) r2 = r10
6: (07) r2 += -8
7: (85) call 1
8: (bf) r7 = r0
9: (15) if r7 == 0x0 goto pc+14
R0=map_value(ks=8,vs=16,id=0),min_value=0,max_value=0 R6=ctx R7=map_value(ks=8,vs=16,id=0),min_value=0,max_value=0 R10=fp
10: (85) call 5
11: (79) r1 = *(u64 *)(r7 +0)
12: (1f) r0 -= r1
13: (7b) *(u64 *)(r7 +0) = r0
14: (b7) r1 = 10000000
15: (2d) if r1 > r0 goto pc+8
R0=inv,min_value=10000000 R1=imm10000000,min_value=10000000,max_value=10000000 R6=ctx R7=map_value(ks=8,vs=16,id=0),min_value=0,max_value=0 R10=fp
16: (18) r2 = 0xffff884e22741800
18: (bf) r1 = r6
19: (18) r3 = 0xffffffff
21: (bf) r4 = r7
22: (b7) r5 = 16
23: (85) call 25
R4 type=map_value expected=fp

Traceback (most recent call last):
File "./kvm_vmexit_slower.py", line 88, in
fire.Fire(main)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 138, in Fire
component_trace = _Fire(component, args, parsed_flag_args, context, name)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 471, in _Fire
target=component.name)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 675, in _CallAndUpdateTrace
component = fn(*varargs, **kwargs)
File "./kvm_vmexit_slower.py", line 75, in main
b = BPF(text=text)
File "/usr/lib/python2.7/site-packages/bcc/init.py", line 355, in init
self._trace_autoload()
File "/usr/lib/python2.7/site-packages/bcc/init.py", line 1118, in _trace_autoload
fn = self.load_func(func_name, BPF.TRACEPOINT)
File "/usr/lib/python2.7/site-packages/bcc/init.py", line 395, in load_func
(func_name, errstr))
Exception: Failed to load BPF program tracepoint__kvm__kvm_entry: Permission denied

problem2:

$sudo ./kvm_vmexit_slower.py 10 --excludes=12
Traceback (most recent call last):
File "./kvm_vmexit_slower.py", line 88, in
fire.Fire(main)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 138, in Fire
component_trace = _Fire(component, args, parsed_flag_args, context, name)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 471, in _Fire
target=component.name)
File "/usr/lib/python2.7/site-packages/fire/core.py", line 675, in _CallAndUpdateTrace
component = fn(*varargs, **kwargs)
File "./kvm_vmexit_slower.py", line 61, in main
if len(excludes) > 0:
TypeError: object of type 'int' has no len()

[mmisono]

Hi,
As of problem2, it is fixed for now (05f8c0c).
As of problem1, the error reason is bpf_perf_event_output() does not accept a bpf map value as an argument. This is changed since Linux 4.11.
So, the solution is upgrading the kernel, or, I don't try it but the following might work:

diff --git a/kvm_vmexit_slower.py b/kvm_vmexit_slower.py
index 5c9fad9..7ad30b9 100755
--- a/kvm_vmexit_slower.py
+++ b/kvm_vmexit_slower.py
@@ -47,7 +47,8 @@ TRACEPOINT_PROBE(kvm, kvm_entry) {
     if (st != 0){
         st->time = bpf_ktime_get_ns() - st->time;
         if(st->time >= THRESH){
-            events.perf_submit(args, st, sizeof(struct data));
+            struct data st2 = *st;
+            events.perf_submit(args, &st2, sizeof(struct data));
         }
     }
     return 0;