extend -smp parsing to include cores= and threads= options

For injecting multi-core and multi-threading CPU topology into guests
extend the -smp syntax to accommodate cores and threads specification.
Syntax: -smp smp_value[,cores=nr_cores][,threads=nr_threads]\
[,socket=nr_sockets][,maxcpus=max_cpus]
smp_value is the legacy value specifying the total number of vCPUs for
the guest. If you specify one of cores, threads or sockets this value
can be omitted. Missing values will be computed to fulfill:
smp_value = nr_cores * nr_threads * nr_sockets
where it will favour sockets over cores over threads (to mimic the
current behavior, which will only inject multiple sockets.)
So -smp 4,threads=2 will inject two sockets with 2 threads each,
-smp cores=4 is an abbreviation for -smp 4,cores=4,threads=1,sockets=1.
If max_cpus (the number of hotpluggable CPUs) is omitted, it will
be set to smp_value.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 57 insertions, 9 deletions

diff --git a/vl.c b/vl.c
index c164f45aad..3a247aeabb 100644
--- a/vl.c
+++ b/vl.c
@@ -217,6 +217,8 @@ int usb_enabled = 0;
 int singlestep = 0;
 int smp_cpus = 1;
 int max_cpus = 0;
+int smp_cores = 1;
+int smp_threads = 1;
 const char *vnc_display;
 int acpi_enabled = 1;
 int no_hpet = 0;
@@ -2356,6 +2358,56 @@ static void numa_add(const char *optarg)
     return;
 }
 
+static void smp_parse(const char *optarg)
+{
+    int smp, sockets = 0, threads = 0, cores = 0;
+    char *endptr;
+    char option[128];
+
+    smp = strtoul(optarg, &endptr, 10);
+    if (endptr != optarg) {
+        if (*endptr == ',') {
+            endptr++;
+        }
+    }
+    if (get_param_value(option, 128, "sockets", endptr) != 0)
+        sockets = strtoull(option, NULL, 10);
+    if (get_param_value(option, 128, "cores", endptr) != 0)
+        cores = strtoull(option, NULL, 10);
+    if (get_param_value(option, 128, "threads", endptr) != 0)
+        threads = strtoull(option, NULL, 10);
+    if (get_param_value(option, 128, "maxcpus", endptr) != 0)
+        max_cpus = strtoull(option, NULL, 10);
+
+    /* compute missing values, prefer sockets over cores over threads */
+    if (smp == 0 || sockets == 0) {
+        sockets = sockets > 0 ? sockets : 1;
+        cores = cores > 0 ? cores : 1;
+        threads = threads > 0 ? threads : 1;
+        if (smp == 0) {
+            smp = cores * threads * sockets;
+        } else {
+            sockets = smp / (cores * threads);
+        }
+    } else {
+        if (cores == 0) {
+            threads = threads > 0 ? threads : 1;
+            cores = smp / (sockets * threads);
+        } else {
+            if (sockets == 0) {
+                sockets = smp / (cores * threads);
+            } else {
+                threads = smp / (cores * sockets);
+            }
+        }
+    }
+    smp_cpus = smp;
+    smp_cores = cores > 0 ? cores : 1;
+    smp_threads = threads > 0 ? threads : 1;
+    if (max_cpus == 0)
+        max_cpus = smp_cpus;
+}
+
 /***********************************************************/
 /* USB devices */
 
@@ -3565,6 +3617,8 @@ void qemu_init_vcpu(void *_env)
 
     if (kvm_enabled())
         kvm_init_vcpu(env);
+    env->nr_cores = smp_cores;
+    env->nr_threads = smp_threads;
     return;
 }
 
@@ -3888,6 +3942,8 @@ void qemu_init_vcpu(void *_env)
         kvm_start_vcpu(env);
     else
         tcg_init_vcpu(env);
+    env->nr_cores = smp_cores;
+    env->nr_threads = smp_threads;
 }
 
 void qemu_notify_event(void)
@@ -5374,18 +5430,11 @@ int main(int argc, char **argv, char **envp)
                 }
                 break;
             case QEMU_OPTION_smp:
-            {
-                char *p;
-                char option[128];
-                smp_cpus = strtol(optarg, &p, 10);
+                smp_parse(optarg);
                 if (smp_cpus < 1) {
                     fprintf(stderr, "Invalid number of CPUs\n");
                     exit(1);
                 }
-                if (*p++ != ',')
-                    break;
-                if (get_param_value(option, 128, "maxcpus", p))
-                    max_cpus = strtol(option, NULL, 0);
                 if (max_cpus < smp_cpus) {
                     fprintf(stderr, "maxcpus must be equal to or greater than "
                             "smp\n");
@@ -5396,7 +5445,6 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
-            }
 	    case QEMU_OPTION_vnc:
                 display_type = DT_VNC;
 		vnc_display = optarg;