virConnectCompareCPU: Introduce FAIL_INCOMPATIBLE flag

The new VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE flag for
virConnectCompareCPU can be used to get an error
(VIR_ERR_CPU_INCOMPATIBLE) describing the incompatibility instead of the
usual VIR_CPU_COMPARE_INCOMPATIBLE return code.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

include/libvirt/libvirt.h.in

@@ -4122,6 +4122,11 @@ typedef enum {
 #endif
 } virCPUCompareResult;
 
+typedef enum {
+    VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE = (1 << 0), /* treat incompatible
+                                                             CPUs as failure */
+} virConnectCompareCPUFlags;
+
 int virConnectCompareCPU(virConnectPtr conn,
                          const char *xmlDesc,
                          unsigned int flags);

src/bhyve/bhyve_driver.c

@@ -1318,21 +1318,30 @@ bhyveConnectCompareCPU(virConnectPtr conn,
     bhyveConnPtr driver = conn->privateData;
     int ret = VIR_CPU_COMPARE_ERROR;
     virCapsPtr caps = NULL;
+    bool failIncompatible;
 
-    virCheckFlags(0, VIR_CPU_COMPARE_ERROR);
+    virCheckFlags(VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE,
+                  VIR_CPU_COMPARE_ERROR);
 
     if (virConnectCompareCPUEnsureACL(conn) < 0)
         goto cleanup;
 
+    failIncomaptible = !!(flags & VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE);
+
     if (!(caps = bhyveDriverGetCapabilities(driver)))
         goto cleanup;
 
     if (!caps->host.cpu ||
         !caps->host.cpu->model) {
+        if (failIncomaptible) {
+            virReportError(VIR_ERR_CPU_INCOMPATIBLE, "%s",
+                           _("cannot get host CPU capabilities"));
+        } else {
             VIR_WARN("cannot get host CPU capabilities");
             ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+        }
     } else {
-        ret = cpuCompareXML(caps->host.cpu, xmlDesc, false);
+        ret = cpuCompareXML(caps->host.cpu, xmlDesc, failIncomaptible);
     }
 
  cleanup:

src/libvirt.c

@@ -17245,11 +17245,16 @@ virConnectIsSecure(virConnectPtr conn)
  * virConnectCompareCPU:
  * @conn: virConnect connection
  * @xmlDesc: XML describing the CPU to compare with host CPU
- * @flags: extra flags; not used yet, so callers should always pass 0
+ * @flags: bitwise-OR of virConnectCompareCPUFlags
  *
  * Compares the given CPU description with the host CPU
  *
- * Returns comparison result according to enum virCPUCompareResult
+ * Returns comparison result according to enum virCPUCompareResult. If
+ * VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE is used and @xmlDesc CPU is
+ * incompatible with host CPU, this function will return VIR_CPU_COMPARE_ERROR
+ * (instead of VIR_CPU_COMPARE_INCOMPATIBLE) and the error will use the
+ * VIR_ERR_CPU_INCOMPATIBLE code with a message providing more details about
+ * the incompatibility.
  */
 int
 virConnectCompareCPU(virConnectPtr conn,

src/qemu/qemu_driver.c

@@ -11514,21 +11514,30 @@ qemuConnectCompareCPU(virConnectPtr conn,
     virQEMUDriverPtr driver = conn->privateData;
     int ret = VIR_CPU_COMPARE_ERROR;
     virCapsPtr caps = NULL;
+    bool failIncomaptible;
 
-    virCheckFlags(0, VIR_CPU_COMPARE_ERROR);
+    virCheckFlags(VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE,
+                  VIR_CPU_COMPARE_ERROR);
 
     if (virConnectCompareCPUEnsureACL(conn) < 0)
         goto cleanup;
 
+    failIncomaptible = !!(flags & VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE);
+
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
     if (!caps->host.cpu ||
         !caps->host.cpu->model) {
+        if (failIncomaptible) {
+            virReportError(VIR_ERR_CPU_INCOMPATIBLE, "%s",
+                           _("cannot get host CPU capabilities"));
+        } else {
             VIR_WARN("cannot get host CPU capabilities");
             ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+        }
     } else {
-        ret = cpuCompareXML(caps->host.cpu, xmlDesc, false);
+        ret = cpuCompareXML(caps->host.cpu, xmlDesc, failIncomaptible);
     }
 
  cleanup:

tools/virsh-domain.c

@@ -6214,6 +6214,10 @@ static const vshCmdOptDef opts_cpu_compare[] = {
      .flags = VSH_OFLAG_REQ,
      .help = N_("file containing an XML CPU description")
     },
+    {.name = "error",
+     .type = VSH_OT_BOOL,
+     .help = N_("report error if CPUs are incompatible")
+    },
     {.name = NULL}
 };
 
@@ -6225,11 +6229,14 @@ cmdCPUCompare(vshControl *ctl, const vshCmd *cmd)
     char *buffer;
     int result;
     char *snippet = NULL;
-
+    unsigned int flags = 0;
     xmlDocPtr xml = NULL;
     xmlXPathContextPtr ctxt = NULL;
     xmlNodePtr node;
 
+    if (vshCommandOptBool(cmd, "error"))
+        flags |= VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE;
+
     if (vshCommandOptStringReq(ctl, cmd, "file", &from) < 0)
         return false;
 
@@ -6253,7 +6260,7 @@ cmdCPUCompare(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
-    result = virConnectCompareCPU(ctl->conn, snippet, 0);
+    result = virConnectCompareCPU(ctl->conn, snippet, flags);
 
     switch (result) {
     case VIR_CPU_COMPARE_INCOMPATIBLE:

tools/virsh.pod

@@ -535,14 +535,17 @@ resulting XML description will explicitly include all features that make
 up the CPU, without this option features that are part of the CPU model
 will not be listed in the XML description.
 
-=item B<cpu-compare> I<FILE>
+=item B<cpu-compare> I<FILE> [I<--error>]
 
 Compare CPU definition from XML <file> with host CPU. The XML <file> may
 contain either host or guest CPU definition. The host CPU definition is the
 <cpu> element and its contents as printed by B<capabilities> command. The
 guest CPU definition is the <cpu> element and its contents from domain XML
 definition. For more information on guest CPU definition see:
-L<http://libvirt.org/formatdomain.html#elementsCPU>
+L<http://libvirt.org/formatdomain.html#elementsCPU>. If I<--error> is
+specified, the command will return an error when the given CPU is
+incompatible with host CPU and a message providing more details about the
+incompatibility will be printed out.
 
 =item B<echo> [I<--shell>] [I<--xml>] [I<arg>...]