qga: implement the guest-get-vcpus for windows

Signed-off-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
* report rather than assert when VCPU count == 0
* fix up subject: s/set-vcpus/get-vcpus/
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

qga/commands-win32.c

@@ -1223,7 +1223,71 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, Error **errp)
 
 GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
 {
-    error_setg(errp, QERR_UNSUPPORTED);
+    PSYSTEM_LOGICAL_PROCESSOR_INFORMATION pslpi, ptr;
+    DWORD length;
+    GuestLogicalProcessorList *head, **link;
+    Error *local_err = NULL;
+    int64_t current;
+
+    ptr = pslpi = NULL;
+    length = 0;
+    current = 0;
+    head = NULL;
+    link = &head;
+
+    if ((GetLogicalProcessorInformation(pslpi, &length) == FALSE) &&
+        (GetLastError() == ERROR_INSUFFICIENT_BUFFER) &&
+        (length > sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION))) {
+        ptr = pslpi = g_malloc0(length);
+        if (GetLogicalProcessorInformation(pslpi, &length) == FALSE) {
+            error_setg(&local_err, "Failed to get processor information: %d",
+                       (int)GetLastError());
+        }
+    } else {
+        error_setg(&local_err,
+                   "Failed to get processor information buffer length: %d",
+                   (int)GetLastError());
+    }
+
+    while ((local_err == NULL) && (length > 0)) {
+        if (pslpi->Relationship == RelationProcessorCore) {
+            ULONG_PTR cpu_bits = pslpi->ProcessorMask;
+
+            while (cpu_bits > 0) {
+                if (!!(cpu_bits & 1)) {
+                    GuestLogicalProcessor *vcpu;
+                    GuestLogicalProcessorList *entry;
+
+                    vcpu = g_malloc0(sizeof *vcpu);
+                    vcpu->logical_id = current++;
+                    vcpu->online = true;
+                    vcpu->has_can_offline = false;
+
+                    entry = g_malloc0(sizeof *entry);
+                    entry->value = vcpu;
+
+                    *link = entry;
+                    link = &entry->next;
+                }
+                cpu_bits >>= 1;
+            }
+        }
+        length -= sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
+        pslpi++; /* next entry */
+    }
+
+    g_free(ptr);
+
+    if (local_err == NULL) {
+        if (head != NULL) {
+            return head;
+        }
+        /* there's no guest with zero VCPUs */
+        error_setg(&local_err, "Guest reported zero VCPUs");
+    }
+
+    qapi_free_GuestLogicalProcessorList(head);
+    error_propagate(errp, local_err);
     return NULL;
 }
 
@@ -1340,7 +1404,7 @@ GList *ga_command_blacklist_init(GList *blacklist)
 {
     const char *list_unsupported[] = {
         "guest-suspend-hybrid",
-        "guest-get-vcpus", "guest-set-vcpus",
+        "guest-set-vcpus",
         "guest-get-memory-blocks", "guest-set-memory-blocks",
         "guest-get-memory-block-size",
         "guest-fsfreeze-freeze-list",