[Qemu-devel] [PATCH v3 0/3] trace: Add events to track vCPU lifecycle

[Qemu-devel] [PATCH v3 0/3] trace: Add events to track vCPU lifecycle

[Lluís Vilanova]

Adds events to track vCPU hot-(un)plugging and reset.

As a bonus, first patch fixes per-vCPU dynamic event state initialization,
making the current late initialization code obsolete.

NOTE: This series is missing CPU hot-unplug, since I could not find a generic
      point to hook the event.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---

Changes in v3
=============

* Remove code for trace_fini_vcpu(), since there is no full support for
  hot-unplugging.


Changes in v2
=============

* Properly support vCPU hot-plugging to "inherit" dynamic event states.
* Rename event "guest_cpu_init" to "guest_cpu_enter".


Lluís Vilanova (3):
      trace: Properly initialize dynamic event states in hot-plugged vCPUs
      trace: Add event "guest_cpu_enter"
      trace: Add event "guest_cpu_reset"


 bsd-user/main.c        |    1 -
 linux-user/main.c      |    1 -
 qom/cpu.c              |    6 ++++++
 stubs/trace-control.c  |    6 ++++++
 trace-events           |   13 +++++++++++++
 trace/control-target.c |   40 ++++++++++++++++++++++++++++++++++++++++
 trace/control.c        |   19 -------------------
 trace/control.h        |   19 ++++++++-----------
 vl.c                   |    1 -
 9 files changed, 73 insertions(+), 33 deletions(-)


To: qemu-devel@nongnu.org
Cc: Stefan Hajnoczi <stefanha@redhat.com>

[Qemu-devel] [PATCH v3 1/3] trace: Properly initialize dynamic event states in hot-plugged vCPUs

[Lluís Vilanova]

Every time a vCPU is hot-plugged, it will "inherit" its tracing state
from the global state array. That is, if *any* existing vCPU has an
event enabled, new vCPUs will have too.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 bsd-user/main.c        |    1 -
 linux-user/main.c      |    1 -
 qom/cpu.c              |    3 +++
 stubs/trace-control.c  |    6 ++++++
 trace/control-target.c |   37 +++++++++++++++++++++++++++++++++++++
 trace/control.c        |   19 -------------------
 trace/control.h        |   19 ++++++++-----------
 vl.c                   |    1 -
 8 files changed, 54 insertions(+), 33 deletions(-)

diff --git a/bsd-user/main.c b/bsd-user/main.c
index 0fb08e4..f58bb43 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -1133,7 +1133,6 @@ int main(int argc, char **argv)
         gdbserver_start (gdbstub_port);
         gdb_handlesig(cpu, 0);
     }
-    trace_init_vcpu_events();
     cpu_loop(env);
     /* never exits */
     return 0;
diff --git a/linux-user/main.c b/linux-user/main.c
index f2f4d2f..b792c91 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -4810,7 +4810,6 @@ int main(int argc, char **argv, char **envp)
         }
         gdb_handlesig(cpu, 0);
     }
-    trace_init_vcpu_events();
     cpu_loop(env);
     /* never exits */
     return 0;
diff --git a/qom/cpu.c b/qom/cpu.c
index 2553247..7e2e523 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -333,6 +333,9 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
         cpu_synchronize_post_init(cpu);
         cpu_resume(cpu);
     }
+
+    /* NOTE: latest generic point where the cpu is fully relized */
+    trace_init_vcpu(cpu);
 }
 
 static void cpu_common_initfn(Object *obj)
diff --git a/stubs/trace-control.c b/stubs/trace-control.c
index 2dfcd9f..f765a02 100644
--- a/stubs/trace-control.c
+++ b/stubs/trace-control.c
@@ -44,3 +44,9 @@ void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
     /* should never be called on non-target binaries */
     abort();
 }
+
+void trace_init_vcpu(CPUState *vcpu)
+{
+    /* should never be called on non-target binaries */
+    abort();
+}
diff --git a/trace/control-target.c b/trace/control-target.c
index 72081e2..3b7d99b 100644
--- a/trace/control-target.c
+++ b/trace/control-target.c
@@ -81,3 +81,40 @@ void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
         }
     }
 }
+
+static bool adding_first_cpu(void)
+{
+    CPUState *cpu;
+    size_t count = 0;
+    CPU_FOREACH(cpu) {
+        count++;
+        if (count > 1) {
+            return false;
+        }
+    }
+    return true;
+}
+
+void trace_init_vcpu(CPUState *vcpu)
+{
+    TraceEvent *ev = NULL;
+
+    while ((ev = trace_event_pattern("*", ev)) != NULL) {
+        if (trace_event_is_vcpu(ev) &&
+            trace_event_get_state_static(ev) &&
+            trace_event_get_state_dynamic(ev)) {
+            TraceEventID id = trace_event_get_id(ev);
+            if (adding_first_cpu()) {
+                /* check preconditions */
+                assert(trace_events_dstate[id] == 1);
+                /* disable early-init state ... */
+                trace_events_dstate[id] = 0;
+                trace_events_enabled_count--;
+                /* ... and properly re-enable */
+                trace_event_set_vcpu_state_dynamic(vcpu, ev, true);
+            } else {
+                trace_event_set_vcpu_state_dynamic(vcpu, ev, true);
+            }
+        }
+    }
+}
diff --git a/trace/control.c b/trace/control.c
index 05d85ac..10b3e9b 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -269,22 +269,3 @@ char *trace_opt_parse(const char *optarg)
 
     return trace_file;
 }
-
-void trace_init_vcpu_events(void)
-{
-    TraceEvent *ev = NULL;
-    while ((ev = trace_event_pattern("*", ev)) != NULL) {
-        if (trace_event_is_vcpu(ev) &&
-            trace_event_get_state_static(ev) &&
-            trace_event_get_state_dynamic(ev)) {
-            TraceEventID id = trace_event_get_id(ev);
-            /* check preconditions */
-            assert(trace_events_dstate[id] == 1);
-            /* disable early-init state ... */
-            trace_events_dstate[id] = 0;
-            trace_events_enabled_count--;
-            /* ... and properly re-enable */
-            trace_event_set_state_dynamic(ev, true);
-        }
-    }
-}
diff --git a/trace/control.h b/trace/control.h
index 27a16fc..a22d112 100644
--- a/trace/control.h
+++ b/trace/control.h
@@ -239,6 +239,14 @@ bool trace_init_backends(void);
 void trace_init_file(const char *file);
 
 /**
+ * trace_init_vcpu:
+ * @vcpu: Added vCPU.
+ *
+ * Set initial dynamic event state for a hot-plugged vCPU.
+ */
+void trace_init_vcpu(CPUState *vcpu);
+
+/**
  * trace_list_events:
  *
  * List all available events.
@@ -269,17 +277,6 @@ extern QemuOptsList qemu_trace_opts;
  */
 char *trace_opt_parse(const char *optarg);
 
-/**
- * trace_init_vcpu_events:
- *
- * Re-synchronize initial event state with vCPUs (which can be created after
- * trace_init_events()).
- *
- * Precondition: event states won't be changed between trace_enable_events() and
- * trace_init_vcpu_events() (e.g., through QMP).
- */
-void trace_init_vcpu_events(void);
-
 
 #include "trace/control-internal.h"
 
diff --git a/vl.c b/vl.c
index ee557a1..5d4d837 100644
--- a/vl.c
+++ b/vl.c
@@ -4613,7 +4613,6 @@ int main(int argc, char **argv, char **envp)
 
     os_setup_post();
 
-    trace_init_vcpu_events();
     main_loop();
     replay_disable_events();
 

[Qemu-devel] [PATCH v3 2/3] trace: Add event "guest_cpu_enter"

[Lluís Vilanova]

Signals the hot-plugging of a new virtual (guest) CPU.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 trace-events           |    8 ++++++++
 trace/control-target.c |    3 +++
 2 files changed, 11 insertions(+)

diff --git a/trace-events b/trace-events
index 616cc52..16a1cb4 100644
--- a/trace-events
+++ b/trace-events
@@ -142,6 +142,14 @@ memory_region_tb_write(int cpu_index, uint64_t addr, uint64_t value, unsigned si
 
 ### Guest events, keep at bottom
 
+
+## vCPU
+
+# Hot-plug a new virtual (guest) CPU
+#
+# Targets: all
+vcpu guest_cpu_enter(void)
+
 # @vaddr: Access' virtual address.
 # @info : Access' information (see below).
 #
diff --git a/trace/control-target.c b/trace/control-target.c
index 3b7d99b..52fcce5 100644
--- a/trace/control-target.c
+++ b/trace/control-target.c
@@ -9,6 +9,7 @@
 
 #include "qemu/osdep.h"
 #include "cpu.h"
+#include "trace.h"
 #include "trace/control.h"
 #include "translate-all.h"
 
@@ -117,4 +118,6 @@ void trace_init_vcpu(CPUState *vcpu)
             }
         }
     }
+
+    trace_guest_cpu_enter(vcpu);
 }

[Qemu-devel] [PATCH v3 3/3] trace: Add event "guest_cpu_reset"

[Lluís Vilanova]

Signals the reset of the state a virtual (guest) CPU.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 qom/cpu.c    |    3 +++
 trace-events |    5 +++++
 2 files changed, 8 insertions(+)

diff --git a/qom/cpu.c b/qom/cpu.c
index 7e2e523..5f0ec6e 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -29,6 +29,7 @@
 #include "qemu/error-report.h"
 #include "sysemu/sysemu.h"
 #include "hw/qdev-properties.h"
+#include "trace.h"
 
 bool cpu_exists(int64_t id)
 {
@@ -245,6 +246,8 @@ void cpu_reset(CPUState *cpu)
     if (klass->reset != NULL) {
         (*klass->reset)(cpu);
     }
+
+    trace_guest_cpu_reset(cpu);
 }
 
 static void cpu_common_reset(CPUState *cpu)
diff --git a/trace-events b/trace-events
index 16a1cb4..fd452c9 100644
--- a/trace-events
+++ b/trace-events
@@ -150,6 +150,11 @@ memory_region_tb_write(int cpu_index, uint64_t addr, uint64_t value, unsigned si
 # Targets: all
 vcpu guest_cpu_enter(void)
 
+# Reset the state of a virtual (guest) CPU
+#
+# Targets: all
+vcpu guest_cpu_reset(void)
+
 # @vaddr: Access' virtual address.
 # @info : Access' information (see below).
 #

Re: [Qemu-devel] [PATCH v3 1/3] trace: Properly initialize dynamic event states in hot-plugged vCPUs

[Stefan Hajnoczi]

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On Mon, Sep 19, 2016 at 02:55:07PM +0200, Lluís Vilanova wrote:
> diff --git a/qom/cpu.c b/qom/cpu.c
> index 2553247..7e2e523 100644
> --- a/qom/cpu.c
> +++ b/qom/cpu.c
> @@ -333,6 +333,9 @@ static void cpu_common_realizefn(DeviceState *dev, Error **errp)
>          cpu_synchronize_post_init(cpu);
>          cpu_resume(cpu);
>      }
> +
> +    /* NOTE: latest generic point where the cpu is fully relized */

s/relized/realized/

I'll fix this typo while merging.

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Re: [Qemu-devel] [PATCH v3 0/3] trace: Add events to track vCPU lifecycle

[Stefan Hajnoczi]

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On Mon, Sep 19, 2016 at 02:55:02PM +0200, Lluís Vilanova wrote:
> Adds events to track vCPU hot-(un)plugging and reset.
> 
> As a bonus, first patch fixes per-vCPU dynamic event state initialization,
> making the current late initialization code obsolete.
> 
> NOTE: This series is missing CPU hot-unplug, since I could not find a generic
>       point to hook the event.
> 
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> ---
> 
> Changes in v3
> =============
> 
> * Remove code for trace_fini_vcpu(), since there is no full support for
>   hot-unplugging.
> 
> 
> Changes in v2
> =============
> 
> * Properly support vCPU hot-plugging to "inherit" dynamic event states.
> * Rename event "guest_cpu_init" to "guest_cpu_enter".
> 
> 
> Lluís Vilanova (3):
>       trace: Properly initialize dynamic event states in hot-plugged vCPUs
>       trace: Add event "guest_cpu_enter"
>       trace: Add event "guest_cpu_reset"
> 
> 
>  bsd-user/main.c        |    1 -
>  linux-user/main.c      |    1 -
>  qom/cpu.c              |    6 ++++++
>  stubs/trace-control.c  |    6 ++++++
>  trace-events           |   13 +++++++++++++
>  trace/control-target.c |   40 ++++++++++++++++++++++++++++++++++++++++
>  trace/control.c        |   19 -------------------
>  trace/control.h        |   19 ++++++++-----------
>  vl.c                   |    1 -
>  9 files changed, 73 insertions(+), 33 deletions(-)
> 
> 
> To: qemu-devel@nongnu.org
> Cc: Stefan Hajnoczi <stefanha@redhat.com>

Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing

Stefan

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