conf: include x86 microcode version in virsh capabilities

A microcode update can cause the CPUID bits to change; an example
from the past was the update that disabled TSX on several Haswell and
Broadwell machines.

In order to track the x86 microcode version in the QEMU capabilities,
we have to fetch it and store it in the host CPU.  This also makes the
version visible in "virsh capabilities", which is a nice side effect.

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

src/conf/cpu_conf.c

@@ -130,6 +130,7 @@ virCPUDefCopyModelFilter(virCPUDefPtr dst,
         VIR_STRDUP(dst->vendor_id, src->vendor_id) < 0 ||
         VIR_ALLOC_N(dst->features, src->nfeatures) < 0)
         return -1;
+    dst->microcodeVersion = src->microcodeVersion;
     dst->nfeatures_max = src->nfeatures;
     dst->nfeatures = 0;
 
@@ -181,6 +182,7 @@ virCPUDefStealModel(virCPUDefPtr dst,
 
     VIR_STEAL_PTR(dst->model, src->model);
     VIR_STEAL_PTR(dst->features, src->features);
+    dst->microcodeVersion = src->microcodeVersion;
     dst->nfeatures_max = src->nfeatures_max;
     src->nfeatures_max = 0;
     dst->nfeatures = src->nfeatures;
@@ -382,6 +384,14 @@ virCPUDefParseXML(xmlXPathContextPtr ctxt,
             goto cleanup;
         }
         VIR_FREE(arch);
+
+        if (virXPathBoolean("boolean(./microcode[1]/@version)", ctxt) > 0 &&
+            virXPathUInt("string(./microcode[1]/@version)", ctxt,
+                         &def->microcodeVersion) < 0) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("invalid microcode version"));
+            goto cleanup;
+        }
     }
 
     if (!(def->model = virXPathString("string(./model[1])", ctxt)) &&
@@ -720,6 +730,10 @@ virCPUDefFormatBuf(virBufferPtr buf,
     if (formatModel && def->vendor)
         virBufferEscapeString(buf, "<vendor>%s</vendor>\n", def->vendor);
 
+    if (def->type == VIR_CPU_TYPE_HOST && def->microcodeVersion)
+        virBufferAsprintf(buf, "<microcode version='%u'/>\n",
+                          def->microcodeVersion);
+
     if (def->sockets && def->cores && def->threads) {
         virBufferAddLit(buf, "<topology");
         virBufferAsprintf(buf, " sockets='%u'", def->sockets);

src/conf/cpu_conf.h

@@ -133,6 +133,7 @@ struct _virCPUDef {
     char *vendor_id;    /* vendor id returned by CPUID in the guest */
     int fallback;       /* enum virCPUFallback */
     char *vendor;
+    unsigned int microcodeVersion;
     unsigned int sockets;
     unsigned int cores;
     unsigned int threads;

src/cpu/cpu_x86.c

@@ -33,6 +33,7 @@
 #include "virbuffer.h"
 #include "virendian.h"
 #include "virstring.h"
+#include "virhostcpu.h"
 
 #define VIR_FROM_THIS VIR_FROM_CPU
 
@@ -153,6 +154,8 @@ struct _virCPUx86Map {
 };
 
 static virCPUx86MapPtr cpuMap;
+static unsigned int microcodeVersion;
+
 int virCPUx86DriverOnceInit(void);
 VIR_ONCE_GLOBAL_INIT(virCPUx86Driver);
 
@@ -1409,6 +1412,8 @@ virCPUx86DriverOnceInit(void)
     if (!(cpuMap = virCPUx86LoadMap()))
         return -1;
 
+    microcodeVersion = virHostCPUGetMicrocodeVersion();
+
     return 0;
 }
 
@@ -2424,6 +2429,9 @@ virCPUx86GetHost(virCPUDefPtr cpu,
     virCPUDataPtr cpuData = NULL;
     int ret = -1;
 
+    if (virCPUx86DriverInitialize() < 0)
+        goto cleanup;
+
     if (!(cpuData = virCPUDataNew(archs[0])))
         goto cleanup;
 
@@ -2432,6 +2440,7 @@ virCPUx86GetHost(virCPUDefPtr cpu,
         goto cleanup;
 
     ret = x86DecodeCPUData(cpu, cpuData, models);
+    cpu->microcodeVersion = microcodeVersion;
 
  cleanup:
     virCPUx86DataFree(cpuData);