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[libvirt] [PATCH 1/2] cpu_x86: Disable TSX on broken models



All Intel Haswell processors (except Xeon E7 v3 with stepping >= 4) have
TSX disabled by microcode update. As not all CPUs are guaranteed to be
patched with microcode updates we need to explicitly disable TSX on
affected CPUs to avoid its accidental usage.

https://bugzilla.redhat.com/show_bug.cgi?id=1406791

Signed-off-by: Jiri Denemark <jdenemar redhat com>
---
 src/cpu/cpu_x86.c                                  | 72 ++++++++++++++++++++--
 .../x86_64-cpuid-Core-i5-4670T-guest.xml           |  2 +-
 .../x86_64-cpuid-Core-i5-4670T-host.xml            |  2 +-
 .../x86_64-cpuid-Core-i5-4670T-json.xml            |  2 +-
 4 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
index b3bccd176..bcf50cb9e 100644
--- a/src/cpu/cpu_x86.c
+++ b/src/cpu/cpu_x86.c
@@ -547,6 +547,26 @@ x86MakeSignature(unsigned int family,
 }
 
 
+static void
+x86DataToSignatureFull(const virCPUx86Data *data,
+                       unsigned int *family,
+                       unsigned int *model,
+                       unsigned int *stepping)
+{
+    virCPUx86CPUID leaf1 = { .eax_in = 0x1 };
+    virCPUx86CPUID *cpuid;
+
+    *family = *model = *stepping = 0;
+
+    if (!(cpuid = x86DataCpuid(data, &leaf1)))
+        return;
+
+    *family = ((cpuid->eax >> 20) & 0xff) + ((cpuid->eax >> 8) & 0xf);
+    *model = ((cpuid->eax >> 12) & 0xf0) + ((cpuid->eax >> 4) & 0xf);
+    *stepping = cpuid->eax & 0xf;
+}
+
+
 /* Mask out irrelevant bits (R and Step) from processor signature. */
 #define SIGNATURE_MASK  0x0fff3ff0
 
@@ -1784,9 +1804,44 @@ x86DecodeUseCandidate(virCPUx86ModelPtr current,
 }
 
 
+/**
+ * Drop broken TSX features.
+ */
+static void
+x86DataFilterTSX(virCPUx86Data *data,
+                 virCPUx86VendorPtr vendor,
+                 virCPUx86MapPtr map)
+{
+    unsigned int family;
+    unsigned int model;
+    unsigned int stepping;
+
+    if (!vendor || STRNEQ(vendor->name, "Intel"))
+        return;
+
+    x86DataToSignatureFull(data, &family, &model, &stepping);
+
+    if (family == 6 &&
+        ((model == 63 && stepping < 4) ||
+         model == 60 ||
+         model == 69 ||
+         model == 70)) {
+        virCPUx86FeaturePtr feature;
+
+        VIR_DEBUG("Dropping broken TSX");
+
+        if ((feature = x86FeatureFind(map, "hle")))
+            x86DataSubtract(data, &feature->data);
+
+        if ((feature = x86FeatureFind(map, "rtm")))
+            x86DataSubtract(data, &feature->data);
+    }
+}
+
+
 static int
 x86Decode(virCPUDefPtr cpu,
-          const virCPUx86Data *data,
+          const virCPUx86Data *cpuData,
           const char **models,
           unsigned int nmodels,
           const char *preferred,
@@ -1798,6 +1853,7 @@ x86Decode(virCPUDefPtr cpu,
     virCPUDefPtr cpuCandidate;
     virCPUx86ModelPtr model = NULL;
     virCPUDefPtr cpuModel = NULL;
+    virCPUx86Data data = VIR_CPU_X86_DATA_INIT;
     virCPUx86Data copy = VIR_CPU_X86_DATA_INIT;
     virCPUx86Data features = VIR_CPU_X86_DATA_INIT;
     virCPUx86VendorPtr vendor;
@@ -1808,11 +1864,16 @@ x86Decode(virCPUDefPtr cpu,
     virCheckFlags(VIR_CONNECT_BASELINE_CPU_EXPAND_FEATURES |
                   VIR_CONNECT_BASELINE_CPU_MIGRATABLE, -1);
 
-    if (!data || !(map = virCPUx86GetMap()))
+    if (!cpuData || x86DataCopy(&data, cpuData) < 0)
         return -1;
 
-    vendor = x86DataToVendor(data, map);
-    signature = x86DataToSignature(data);
+    if (!(map = virCPUx86GetMap()))
+        goto cleanup;
+
+    vendor = x86DataToVendor(&data, map);
+    signature = x86DataToSignature(&data);
+
+    x86DataFilterTSX(&data, vendor, map);
 
     /* Walk through the CPU models in reverse order to check newest
      * models first.
@@ -1847,7 +1908,7 @@ x86Decode(virCPUDefPtr cpu,
             continue;
         }
 
-        if (!(cpuCandidate = x86DataToCPU(data, candidate, map)))
+        if (!(cpuCandidate = x86DataToCPU(&data, candidate, map)))
             goto cleanup;
         cpuCandidate->type = cpu->type;
 
@@ -1912,6 +1973,7 @@ x86Decode(virCPUDefPtr cpu,
 
  cleanup:
     virCPUDefFree(cpuModel);
+    virCPUx86DataClear(&data);
     virCPUx86DataClear(&copy);
     virCPUx86DataClear(&features);
     return ret;
diff --git a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-guest.xml b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-guest.xml
index 9c9399562..70d13282b 100644
--- a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-guest.xml
+++ b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-guest.xml
@@ -1,6 +1,6 @@
 <cpu mode='custom' match='exact'>
   <arch>x86_64</arch>
-  <model fallback='forbid'>Haswell</model>
+  <model fallback='forbid'>Haswell-noTSX</model>
   <vendor>Intel</vendor>
   <feature policy='require' name='vme'/>
   <feature policy='require' name='ds'/>
diff --git a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-host.xml b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-host.xml
index b9f95ad87..d1d0bc716 100644
--- a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-host.xml
+++ b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-host.xml
@@ -1,6 +1,6 @@
 <cpu>
   <arch>x86_64</arch>
-  <model>Haswell</model>
+  <model>Haswell-noTSX</model>
   <vendor>Intel</vendor>
   <feature name='vme'/>
   <feature name='ds'/>
diff --git a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-json.xml b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-json.xml
index cf23f59d7..8d3a0b618 100644
--- a/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-json.xml
+++ b/tests/cputestdata/x86_64-cpuid-Core-i5-4670T-json.xml
@@ -1,6 +1,6 @@
 <cpu mode='custom' match='exact'>
   <arch>x86_64</arch>
-  <model fallback='forbid'>Haswell</model>
+  <model fallback='forbid'>Haswell-noTSX</model>
   <vendor>Intel</vendor>
   <feature policy='require' name='vme'/>
   <feature policy='require' name='ss'/>
-- 
2.11.1


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