From 4f1684dd855d48517e04507edadba2fd454e4ada Mon Sep 17 00:00:00 2001
Message-Id: <4f1684dd855d48517e04507edadba2fd454e4ada@dist-git>
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 12 Dec 2017 16:23:40 +0100
Subject: [PATCH] conf: include x86 microcode version in virsh capabiltiies

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.

CVE-2017-5715

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/conf/cpu_conf.c | 14 ++++++++++++++
 src/conf/cpu_conf.h |  1 +
 src/cpu/cpu_x86.c   |  9 +++++++++
 3 files changed, 24 insertions(+)

diff --git a/src/conf/cpu_conf.c b/src/conf/cpu_conf.c
index 669935acf8..7e00299c66 100644
--- a/src/conf/cpu_conf.c
+++ b/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);
diff --git a/src/conf/cpu_conf.h b/src/conf/cpu_conf.h
index d1983f5d4f..9f2e7ee264 100644
--- a/src/conf/cpu_conf.h
+++ b/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;
diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
index 693e571a3d..ad35532fc1 100644
--- a/src/cpu/cpu_x86.c
+++ b/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);
-- 
2.15.1