[PATCH] kvm: kvm_init_vcpu take Error pointer

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Clean up the error handling in kvm_init_vcpu so we can see what went
wrong more easily.

Make it take an Error ** and fill it out with what failed, including
the cpu id, so you can tell if it only fails at a given ID.

Replace the remaining DPRINTF by a trace.

This turns a:
kvm_init_vcpu failed: Invalid argument

into:
kvm_init_vcpu: kvm_get_vcpu failed (256): Invalid argument

and with the trace you then get to see:

19049@1595520414.310107:kvm_init_vcpu index: 169 id: 212
19050@1595520414.310635:kvm_init_vcpu index: 170 id: 256
qemu-system-x86_64: kvm_init_vcpu: kvm_get_vcpu failed (256): Invalid argument

which makes stuff a lot more obvious.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 accel/kvm/kvm-all.c    | 19 ++++++++++++++-----
 accel/kvm/trace-events |  1 +
 accel/stubs/kvm-stub.c |  2 +-
 include/sysemu/kvm.h   |  2 +-
 softmmu/cpus.c         |  6 +-----
 5 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 63ef6af9a1c..0fbece977c7 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -430,17 +430,18 @@ static int kvm_get_vcpu(KVMState *s, unsigned long 
vcpu_id)
     return kvm_vm_ioctl(s, KVM_CREATE_VCPU, (void *)vcpu_id);
 }
 
-int kvm_init_vcpu(CPUState *cpu)
+int kvm_init_vcpu(CPUState *cpu, Error **errp)
 {
     KVMState *s = kvm_state;
     long mmap_size;
     int ret;
 
-    DPRINTF("kvm_init_vcpu\n");
+    trace_kvm_init_vcpu(cpu->cpu_index, kvm_arch_vcpu_id(cpu));
 
     ret = kvm_get_vcpu(s, kvm_arch_vcpu_id(cpu));
     if (ret < 0) {
-        DPRINTF("kvm_create_vcpu failed\n");
+        error_setg_errno(errp, -ret, "kvm_init_vcpu: kvm_get_vcpu failed 
(%lu)",
+                         kvm_arch_vcpu_id(cpu));
         goto err;
     }
 
@@ -451,7 +452,8 @@ int kvm_init_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");
+        error_setg_errno(errp, -mmap_size,
+                         "kvm_init_vcpu: KVM_GET_VCPU_MMAP_SIZE failed");
         goto err;
     }
 
@@ -459,7 +461,9 @@ int kvm_init_vcpu(CPUState *cpu)
                         cpu->kvm_fd, 0);
     if (cpu->kvm_run == MAP_FAILED) {
         ret = -errno;
-        DPRINTF("mmap'ing vcpu state failed\n");
+        error_setg_errno(errp, ret,
+                         "kvm_init_vcpu: mmap'ing vcpu state failed (%lu)",
+                         kvm_arch_vcpu_id(cpu));
         goto err;
     }
 
@@ -469,6 +473,11 @@ int kvm_init_vcpu(CPUState *cpu)
     }
 
     ret = kvm_arch_init_vcpu(cpu);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "kvm_init_vcpu: kvm_arch_init_vcpu failed (%lu)",
+                         kvm_arch_vcpu_id(cpu));
+    }
 err:
     return ret;
 }
diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events
index a68eb665343..e15ae8980d3 100644
--- a/accel/kvm/trace-events
+++ b/accel/kvm/trace-events
@@ -8,6 +8,7 @@ kvm_run_exit(int cpu_index, uint32_t reason) "cpu_index %d, 
reason %d"
 kvm_device_ioctl(int fd, int type, void *arg) "dev fd %d, type 0x%x, arg %p"
 kvm_failed_reg_get(uint64_t id, const char *msg) "Warning: Unable to retrieve 
ONEREG %" PRIu64 " from KVM: %s"
 kvm_failed_reg_set(uint64_t id, const char *msg) "Warning: Unable to set 
ONEREG %" PRIu64 " to KVM: %s"
+kvm_init_vcpu(int cpu_index, unsigned long arch_cpu_id) "index: %d id: %lu"
 kvm_irqchip_commit_routes(void) ""
 kvm_irqchip_add_msi_route(char *name, int vector, int virq) "dev %s vector %d 
virq %d"
 kvm_irqchip_update_msi_route(int virq) "Updating MSI route virq=%d"
diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
index 82f118d2df9..cd573bfe3d9 100644
--- a/accel/stubs/kvm-stub.c
+++ b/accel/stubs/kvm-stub.c
@@ -37,7 +37,7 @@ int kvm_destroy_vcpu(CPUState *cpu)
     return -ENOSYS;
 }
 
-int kvm_init_vcpu(CPUState *cpu)
+int kvm_init_vcpu(CPUState *cpu, Error **errp)
 {
     return -ENOSYS;
 }
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index b4174d941c2..410848af514 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -216,7 +216,7 @@ int kvm_has_many_ioeventfds(void);
 int kvm_has_gsi_routing(void);
 int kvm_has_intx_set_mask(void);
 
-int kvm_init_vcpu(CPUState *cpu);
+int kvm_init_vcpu(CPUState *cpu, Error **errp);
 int kvm_cpu_exec(CPUState *cpu);
 int kvm_destroy_vcpu(CPUState *cpu);
 
diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index a802e899abb..9725fd9951f 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -1170,11 +1170,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
     cpu->can_do_io = 1;
     current_cpu = cpu;
 
-    r = kvm_init_vcpu(cpu);
-    if (r < 0) {
-        error_report("kvm_init_vcpu failed: %s", strerror(-r));
-        exit(1);
-    }
+    kvm_init_vcpu(cpu, &error_fatal);
 
     kvm_init_cpu_signals(cpu);
 
-- 
2.26.2