[Qemu-devel] [PATCH 7/8] [PATCH RFC v2] s390-qemu: cpu hotplug - Infrastructure for Cpu Devices

["Jason J. Herne" <jjherne@us.ibm.com>]

From: "Jason J. Herne" <jjherne@us.ibm.com>

Add infrastructure for treating cpus as devices. This patch allows cpus to be
specified using a combination of '-smp' and '-device cpu'.  This approach
forces a change in the way cpus are counted via smp_cpus.

Signed-off-by: Jason J. Herne <jjherne@us.ibm.com>
---
 include/hw/boards.h |    3 ++
 vl.c                |   95 +++++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 84 insertions(+), 14 deletions(-)

diff --git a/include/hw/boards.h b/include/hw/boards.h
index ed427a1..b0c86bf 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -47,8 +47,11 @@ typedef struct QEMUMachine {
     GlobalProperty *compat_props;
     struct QEMUMachine *next;
     const char *hw_version;
+    const char *cpu_device_str;
 } QEMUMachine;
 
+#define CPUS_ARE_DEVICES(qemu_mach)    (qemu_mach->cpu_device_str != NULL)
+
 int qemu_register_machine(QEMUMachine *m);
 QEMUMachine *find_default_machine(void);
 
diff --git a/vl.c b/vl.c
index 71e1e6d..873834f 100644
--- a/vl.c
+++ b/vl.c
@@ -546,6 +546,46 @@ static int default_driver_check(QemuOpts *opts, void *opaque)
     return 0;
 }
 
+static void convert_smp_to_cpu_devices(QEMUMachine *machine)
+{
+    int i;
+    QemuOpts *opts;
+
+    for (i = 0; i < smp_cpus; i++) {
+        opts = qemu_opts_create_nofail(qemu_find_opts("device"));
+        qemu_opt_set(opts, "driver", machine->cpu_device_str);
+    }
+    smp_cpus = 0;
+}
+
+static int count_cpu_devices(QemuOpts *opts, void *opaque)
+{
+    const char *driver = qemu_opt_get(opts, "driver");
+    QEMUMachine *machine = (QEMUMachine *)opaque;
+
+    /* Skip non-cpu devices*/
+    if (!driver || strcmp(driver, machine->cpu_device_str) != 0) {
+        return 0;
+    }
+
+    smp_cpus += 1;
+    return 0;
+}
+
+static int handle_cpu_device(QemuOpts *opts, void *opaque)
+{
+    const char *driver = qemu_opt_get(opts, "driver");
+    QEMUMachine *machine = (QEMUMachine *)opaque;
+
+    /* Skip non-cpu devices*/
+    if (!driver || strcmp(driver, machine->cpu_device_str) != 0) {
+        return 0;
+    }
+
+    qdev_device_add(opts);
+    return 0;
+}
+
 /***********************************************************/
 /* QEMU state */
 
@@ -2318,6 +2358,13 @@ static int device_help_func(QemuOpts *opts, void *opaque)
 static int device_init_func(QemuOpts *opts, void *opaque)
 {
     DeviceState *dev;
+    const char *driver = qemu_opt_get(opts, "driver");
+    QEMUMachine *machine = (QEMUMachine *)opaque;
+
+    /* Skip cpu devices*/
+    if (!driver || strcmp(driver, machine->cpu_device_str) == 0) {
+        return 0;
+    }
 
     dev = qdev_device_add(opts);
     if (!dev)
@@ -3630,19 +3677,6 @@ int main(int argc, char **argv, char **envp)
                 break;
             case QEMU_OPTION_smp:
                 smp_parse(optarg);
-                if (smp_cpus < 1) {
-                    fprintf(stderr, "Invalid number of CPUs\n");
-                    exit(1);
-                }
-                if (max_cpus < smp_cpus) {
-                    fprintf(stderr, "maxcpus must be equal to or greater than "
-                            "smp\n");
-                    exit(1);
-                }
-                if (max_cpus > 255) {
-                    fprintf(stderr, "Unsupported number of maxcpus\n");
-                    exit(1);
-                }
                 break;
 	    case QEMU_OPTION_vnc:
 #ifdef CONFIG_VNC
@@ -3965,6 +3999,16 @@ int main(int argc, char **argv, char **envp)
     }
 
     /*
+     * Count cpu devices. Cpu count is determied by adding -device cpu
+     * statements to the number of cpus specified on the -smp statement.
+     */
+    if (CPUS_ARE_DEVICES(machine)) {
+        convert_smp_to_cpu_devices(machine);
+        qemu_opts_foreach(qemu_find_opts("device"), count_cpu_devices,
+                          machine, 0);
+    }
+
+    /*
      * Default to max_cpus = smp_cpus, in case the user doesn't
      * specify a max_cpus value.
      */
@@ -3979,6 +4023,20 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    if (smp_cpus < 1) {
+        fprintf(stderr, "Invalid number of CPUs\n");
+        exit(1);
+    }
+    if (max_cpus < smp_cpus) {
+        fprintf(stderr, "maxcpus must be equal to or greater than the number of"
+                " cpus defined\n");
+        exit(1);
+    }
+    if (max_cpus > 255) {
+        fprintf(stderr, "Unsupported number of maxcpus\n");
+        exit(1);
+    }
+
     /*
      * Get the default machine options from the machine if it is not already
      * specified either by the configuration file or by the command line.
@@ -4305,6 +4363,13 @@ int main(int argc, char **argv, char **envp)
                                  .cpu_model = cpu_model };
     machine->init(&args);
 
+    /* Create cpu devices */
+    if (CPUS_ARE_DEVICES(machine)) {
+        smp_cpus = 0;  /* Reset this because each cpu will count itself */
+        qemu_opts_foreach(qemu_find_opts("device"), handle_cpu_device,
+                          machine, 0);
+    }
+
     if (machine->post_cpu_init) {
         machine->post_cpu_init();
     }
@@ -4324,8 +4389,10 @@ int main(int argc, char **argv, char **envp)
     }
 
     /* init generic devices */
-    if (qemu_opts_foreach(qemu_find_opts("device"), device_init_func, NULL, 1) != 0)
+    if (qemu_opts_foreach(qemu_find_opts("device"),
+                          device_init_func, machine, 1) != 0) {
         exit(1);
+    }
 
     net_check_clients();
 
-- 
1.7.10.4