[PATCH v3] accel/kvm: Turn DPRINTF macro use into tracepoints

[PATCH v3] accel/kvm: Turn DPRINTF macro use into tracepoints

[Jai Arora]

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Patch removes DRPINTF macro and adds multiple tracepoints
to capture different kvm events.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1827

Signed-off-by: Jai Arora <arorajai2798@gmail.com>
---

Notes:
    v3: Addresses review comments by Alex Bennée
    
    Removes trace events kvm_run_exit_reason, kvm_exit_system_event
    and their usage.
    
    Adds trace event kvm_run_exit_system_event to trace run->system_event.type

 accel/kvm/kvm-all.c    | 28 ++++++----------------------
 accel/kvm/trace-events |  7 ++++++-
 2 files changed, 12 insertions(+), 23 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index e39a810a4e..80ac7b35b7 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -69,16 +69,6 @@
 #define KVM_GUESTDBG_BLOCKIRQ 0
 #endif
 
-//#define DEBUG_KVM
-
-#ifdef DEBUG_KVM
-#define DPRINTF(fmt, ...) \
-    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
-#else
-#define DPRINTF(fmt, ...) \
-    do { } while (0)
-#endif
-
 struct KVMParkedVcpu {
     unsigned long vcpu_id;
     int kvm_fd;
@@ -331,7 +321,7 @@ static int do_kvm_destroy_vcpu(CPUState *cpu)
     struct KVMParkedVcpu *vcpu = NULL;
     int ret = 0;
 
-    DPRINTF("kvm_destroy_vcpu\n");
+    trace_kvm_destroy_vcpu();
 
     ret = kvm_arch_destroy_vcpu(cpu);
     if (ret < 0) {
@@ -341,7 +331,7 @@ static int do_kvm_destroy_vcpu(CPUState *cpu)
     mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
     if (mmap_size < 0) {
         ret = mmap_size;
-        DPRINTF("KVM_GET_VCPU_MMAP_SIZE failed\n");
+        trace_kvm_failed_get_vcpu_mmap_size();
         goto err;
     }
 
@@ -443,7 +433,6 @@ int kvm_init_vcpu(CPUState *cpu, Error **errp)
                                    PAGE_SIZE * KVM_DIRTY_LOG_PAGE_OFFSET);
         if (cpu->kvm_dirty_gfns == MAP_FAILED) {
             ret = -errno;
-            DPRINTF("mmap'ing vcpu dirty gfns failed: %d\n", ret);
             goto err;
         }
     }
@@ -2821,7 +2810,7 @@ int kvm_cpu_exec(CPUState *cpu)
     struct kvm_run *run = cpu->kvm_run;
     int ret, run_ret;
 
-    DPRINTF("kvm_cpu_exec()\n");
+    trace_kvm_cpu_exec();
 
     if (kvm_arch_process_async_events(cpu)) {
         qatomic_set(&cpu->exit_request, 0);
@@ -2848,7 +2837,7 @@ int kvm_cpu_exec(CPUState *cpu)
 
         kvm_arch_pre_run(cpu, run);
         if (qatomic_read(&cpu->exit_request)) {
-            DPRINTF("interrupt exit requested\n");
+	    trace_kvm_interrupt_exit_request();
             /*
              * KVM requires us to reenter the kernel after IO exits to complete
              * instruction emulation. This self-signal will ensure that we
@@ -2878,7 +2867,7 @@ int kvm_cpu_exec(CPUState *cpu)
 
         if (run_ret < 0) {
             if (run_ret == -EINTR || run_ret == -EAGAIN) {
-                DPRINTF("io window exit\n");
+                trace_kvm_io_window_exit();
                 kvm_eat_signals(cpu);
                 ret = EXCP_INTERRUPT;
                 break;
@@ -2900,7 +2889,6 @@ int kvm_cpu_exec(CPUState *cpu)
         trace_kvm_run_exit(cpu->cpu_index, run->exit_reason);
         switch (run->exit_reason) {
         case KVM_EXIT_IO:
-            DPRINTF("handle_io\n");
             /* Called outside BQL */
             kvm_handle_io(run->io.port, attrs,
                           (uint8_t *)run + run->io.data_offset,
@@ -2910,7 +2898,6 @@ int kvm_cpu_exec(CPUState *cpu)
             ret = 0;
             break;
         case KVM_EXIT_MMIO:
-            DPRINTF("handle_mmio\n");
             /* Called outside BQL */
             address_space_rw(&address_space_memory,
                              run->mmio.phys_addr, attrs,
@@ -2920,11 +2907,9 @@ int kvm_cpu_exec(CPUState *cpu)
             ret = 0;
             break;
         case KVM_EXIT_IRQ_WINDOW_OPEN:
-            DPRINTF("irq_window_open\n");
             ret = EXCP_INTERRUPT;
             break;
         case KVM_EXIT_SHUTDOWN:
-            DPRINTF("shutdown\n");
             qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
             ret = EXCP_INTERRUPT;
             break;
@@ -2959,6 +2944,7 @@ int kvm_cpu_exec(CPUState *cpu)
             ret = 0;
             break;
         case KVM_EXIT_SYSTEM_EVENT:
+            trace_kvm_run_exit_system_event(cpu->cpu_index, run->system_event.type);
             switch (run->system_event.type) {
             case KVM_SYSTEM_EVENT_SHUTDOWN:
                 qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
@@ -2976,13 +2962,11 @@ int kvm_cpu_exec(CPUState *cpu)
                 ret = 0;
                 break;
             default:
-                DPRINTF("kvm_arch_handle_exit\n");
                 ret = kvm_arch_handle_exit(cpu, run);
                 break;
             }
             break;
         default:
-            DPRINTF("kvm_arch_handle_exit\n");
             ret = kvm_arch_handle_exit(cpu, run);
             break;
         }
diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events
index 399aaeb0ec..f61a21019a 100644
--- a/accel/kvm/trace-events
+++ b/accel/kvm/trace-events
@@ -25,4 +25,9 @@ kvm_dirty_ring_reaper(const char *s) "%s"
 kvm_dirty_ring_reap(uint64_t count, int64_t t) "reaped %"PRIu64" pages (took %"PRIi64" us)"
 kvm_dirty_ring_reaper_kick(const char *reason) "%s"
 kvm_dirty_ring_flush(int finished) "%d"
-
+kvm_destroy_vcpu(void) ""
+kvm_failed_get_vcpu_mmap_size(void) ""
+kvm_cpu_exec(void) ""
+kvm_interrupt_exit_request(void) ""
+kvm_io_window_exit(void) ""
+kvm_run_exit_system_event(int cpu_index, uint32_t event_type) "cpu_index %d, system_even_type %d"
-- 
2.25.1

Re: [PATCH v3] accel/kvm: Turn DPRINTF macro use into tracepoints

[Alex Bennée]

Jai Arora <arorajai2798@gmail.com> writes:

> Patch removes DRPINTF macro and adds multiple tracepoints
> to capture different kvm events.

maybe add "We drop the DPRINTFs that don't add any additional
information than trace_kvm_run_exit already does."

Otherwise:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

p.s.

It is helpful to add a mini-changelog bellow the --- line so reviewers
can see what changes have already been made to the patch. The git
tooling will strip this log when the maintainer applies the patches.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro