cpuCompare*: Add support for reporting failure on incompatible CPUs

When CPU comparison APIs return VIR_CPU_COMPARE_INCOMPATIBLE, the caller
has no clue why the CPU is considered incompatible with host CPU. And in
some cases, it would be nice to be able to get such info in a client
rather than having to look in logs.

To achieve this, the APIs can be told to return VIR_ERR_CPU_INCOMPATIBLE
error for incompatible CPUs and the reason will be described in the
associated error message.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

include/libvirt/virterror.h

@@ -300,6 +300,8 @@ typedef enum {
                                            was denied */
     VIR_ERR_DBUS_SERVICE = 89,          /* error from a dbus service */
     VIR_ERR_STORAGE_VOL_EXIST = 90,     /* the storage vol already exists */
+    VIR_ERR_CPU_INCOMPATIBLE = 91,      /* given CPU is incompatible with host
+                                           CPU*/
 } virErrorNumber;
 
 /**

src/bhyve/bhyve_driver.c

@@ -1332,7 +1332,7 @@ bhyveConnectCompareCPU(virConnectPtr conn,
         VIR_WARN("cannot get host CPU capabilities");
         ret = VIR_CPU_COMPARE_INCOMPATIBLE;
     } else {
-        ret = cpuCompareXML(caps->host.cpu, xmlDesc);
+        ret = cpuCompareXML(caps->host.cpu, xmlDesc, false);
     }
 
  cleanup:

src/cpu/cpu.c

@@ -92,7 +92,8 @@ cpuGetSubDriver(virArch arch)
  */
 virCPUCompareResult
 cpuCompareXML(virCPUDefPtr host,
-              const char *xml)
+              const char *xml,
+              bool failIncompatible)
 {
     xmlDocPtr doc = NULL;
     xmlXPathContextPtr ctxt = NULL;
@@ -108,7 +109,7 @@ cpuCompareXML(virCPUDefPtr host,
     if (cpu == NULL)
         goto cleanup;
 
-    ret = cpuCompare(host, cpu);
+    ret = cpuCompare(host, cpu, failIncompatible);
 
  cleanup:
     virCPUDefFree(cpu);
@@ -134,7 +135,8 @@ cpuCompareXML(virCPUDefPtr host,
  */
 virCPUCompareResult
 cpuCompare(virCPUDefPtr host,
-           virCPUDefPtr cpu)
+           virCPUDefPtr cpu,
+           bool failIncompatible)
 {
     struct cpuArchDriver *driver;
 
@@ -156,7 +158,7 @@ cpuCompare(virCPUDefPtr host,
         return VIR_CPU_COMPARE_ERROR;
     }
 
-    return driver->compare(host, cpu);
+    return driver->compare(host, cpu, failIncompatible);
 }
 
 

src/cpu/cpu.h

@@ -46,7 +46,8 @@ struct _virCPUData {
 
 typedef virCPUCompareResult
 (*cpuArchCompare)   (virCPUDefPtr host,
-                     virCPUDefPtr cpu);
+                     virCPUDefPtr cpu,
+                     bool failIncompatible);
 
 typedef int
 (*cpuArchDecode)    (virCPUDefPtr cpu,
@@ -119,12 +120,14 @@ struct cpuArchDriver {
 
 extern virCPUCompareResult
 cpuCompareXML(virCPUDefPtr host,
-              const char *xml)
+              const char *xml,
+              bool failIncompatible)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
 extern virCPUCompareResult
 cpuCompare  (virCPUDefPtr host,
-             virCPUDefPtr cpu)
+             virCPUDefPtr cpu,
+             bool failIncompatible)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
 extern int

src/cpu/cpu_aarch64.c

@@ -110,7 +110,8 @@ AArch64Baseline(virCPUDefPtr *cpus,
 
 static virCPUCompareResult
 AArch64Compare(virCPUDefPtr host ATTRIBUTE_UNUSED,
-               virCPUDefPtr cpu ATTRIBUTE_UNUSED)
+               virCPUDefPtr cpu ATTRIBUTE_UNUSED,
+               bool failIncompatible ATTRIBUTE_UNUSED)
 {
     return VIR_CPU_COMPARE_IDENTICAL;
 }

src/cpu/cpu_arm.c

@@ -113,7 +113,8 @@ ArmBaseline(virCPUDefPtr *cpus,
 
 static virCPUCompareResult
 ArmCompare(virCPUDefPtr host ATTRIBUTE_UNUSED,
-           virCPUDefPtr cpu ATTRIBUTE_UNUSED)
+           virCPUDefPtr cpu ATTRIBUTE_UNUSED,
+           bool failMessages ATTRIBUTE_UNUSED)
 {
     return VIR_CPU_COMPARE_IDENTICAL;
 }

src/cpu/cpu_generic.c

@@ -57,17 +57,20 @@ genericHashFeatures(virCPUDefPtr cpu)
 
 static virCPUCompareResult
 genericCompare(virCPUDefPtr host,
-               virCPUDefPtr cpu)
+               virCPUDefPtr cpu,
+               bool failIncompatible)
 {
-    virHashTablePtr hash;
+    virHashTablePtr hash = NULL;
     virCPUCompareResult ret = VIR_CPU_COMPARE_ERROR;
     size_t i;
     unsigned int reqfeatures;
 
     if ((cpu->arch != VIR_ARCH_NONE &&
          host->arch != cpu->arch) ||
-        STRNEQ(host->model, cpu->model))
-        return VIR_CPU_COMPARE_INCOMPATIBLE;
+        STRNEQ(host->model, cpu->model)) {
+        ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+        goto cleanup;
+    }
 
     if ((hash = genericHashFeatures(host)) == NULL)
         goto cleanup;
@@ -102,6 +105,10 @@ genericCompare(virCPUDefPtr host,
 
  cleanup:
     virHashFree(hash);
+    if (failIncompatible && ret == VIR_CPU_COMPARE_INCOMPATIBLE) {
+        ret = VIR_CPU_COMPARE_ERROR;
+        virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
+    }
     return ret;
 }
 

src/cpu/cpu_powerpc.c

@@ -440,13 +440,19 @@ ppcCompute(virCPUDefPtr host,
 
 static virCPUCompareResult
 ppcCompare(virCPUDefPtr host,
-           virCPUDefPtr cpu)
+           virCPUDefPtr cpu,
+           bool failIncompatible)
 {
     if ((cpu->arch == VIR_ARCH_NONE || host->arch == cpu->arch) &&
         STREQ(host->model, cpu->model))
         return VIR_CPU_COMPARE_IDENTICAL;
 
-    return VIR_CPU_COMPARE_INCOMPATIBLE;
+    if (failIncompatible) {
+        virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
+        return VIR_CPU_COMPARE_ERROR;
+    } else {
+        return VIR_CPU_COMPARE_INCOMPATIBLE;
+    }
 }
 
 static int

src/cpu/cpu_x86.c

@@ -1463,9 +1463,25 @@ x86Compute(virCPUDefPtr host,
 
 static virCPUCompareResult
 x86Compare(virCPUDefPtr host,
-           virCPUDefPtr cpu)
+           virCPUDefPtr cpu,
+           bool failIncomaptible)
 {
-    return x86Compute(host, cpu, NULL, NULL);
+    virCPUCompareResult ret;
+    char *message = NULL;
+
+    ret = x86Compute(host, cpu, NULL, &message);
+
+    if (failIncomaptible && ret == VIR_CPU_COMPARE_INCOMPATIBLE) {
+        ret = VIR_CPU_COMPARE_ERROR;
+        if (message) {
+            virReportError(VIR_ERR_CPU_INCOMPATIBLE, "%s", message);
+        } else {
+            virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
+        }
+    }
+    VIR_FREE(message);
+
+    return ret;
 }
 
 

src/qemu/qemu_driver.c

@@ -11528,7 +11528,7 @@ qemuConnectCompareCPU(virConnectPtr conn,
         VIR_WARN("cannot get host CPU capabilities");
         ret = VIR_CPU_COMPARE_INCOMPATIBLE;
     } else {
-        ret = cpuCompareXML(caps->host.cpu, xmlDesc);
+        ret = cpuCompareXML(caps->host.cpu, xmlDesc, false);
     }
 
  cleanup:

src/util/virerror.c

@@ -1277,6 +1277,12 @@ virErrorMsg(virErrorNumber error, const char *info)
             else
                 errmsg = _("error from service: %s");
             break;
+        case VIR_ERR_CPU_INCOMPATIBLE:
+            if (info == NULL)
+                errmsg = _("the CPU is incompatible with host CPU");
+            else
+                errmsg = _("the CPU is incompatible with host CPU: %s");
+            break;
     }
     return errmsg;
 }

tests/cputest.c

@@ -228,7 +228,7 @@ cpuTestCompare(const void *arg)
         !(cpu = cpuTestLoadXML(data->arch, data->name)))
         goto cleanup;
 
-    result = cpuCompare(host, cpu);
+    result = cpuCompare(host, cpu, false);
     if (data->result == VIR_CPU_COMPARE_ERROR)
         virResetLastError();
 
@@ -357,7 +357,7 @@ cpuTestBaseline(const void *arg)
     for (i = 0; i < ncpus; i++) {
         virCPUCompareResult cmp;
 
-        cmp = cpuCompare(cpus[i], baseline);
+        cmp = cpuCompare(cpus[i], baseline, false);
         if (cmp != VIR_CPU_COMPARE_SUPERSET &&
             cmp != VIR_CPU_COMPARE_IDENTICAL) {
             if (virTestGetVerbose()) {