[libvirt PATCH v2 11/14] qemu_capabilities: Translate CPU blockers

[Jiri Denemark]

Since commit "cpu_x86: Disable blockers from unusable CPU models"
(v3.8.0-99-g9c9620af1d) we explicitly disable CPU features reported by
QEMU as usability blockers for a particular CPU model when creating
baseline or host-model CPU definition. When QEMU changed canonical names
for some features (mostly those with '_' in their names), we forgot to
translate the blocker lists to names used by libvirt and the renamed
features would no longer be explicitly disabled in the created CPU model
even if they were reported as blockers by QEMU.

For example, on a host where EPYC CPU model has the following blockers

    <blocker name='sha-ni'/>
    <blocker name='mmxext'/>
    <blocker name='fxsr-opt'/>
    <blocker name='cr8legacy'/>
    <blocker name='sse4a'/>
    <blocker name='misalignsse'/>
    <blocker name='osvw'/>

we would fail to disable 'fxsr-opt':

    <cpu mode='custom' match='exact'>
      <model fallback='forbid'>EPYC</model>
      <feature policy='disable' name='sha-ni'/>
      <feature policy='disable' name='mmxext'/>
      <feature policy='disable' name='cr8legacy'/>
      <feature policy='disable' name='sse4a'/>
      <feature policy='disable' name='misalignsse'/>
      <feature policy='disable' name='osvw'/>
      <feature policy='disable' name='monitor'/>
    </cpu>

The 'monitor' feature is disabled even though it is not reported as a
blocker by QEMU because libvirt's definition of EPYC includes the
feature while it is missing in EPYC definition in QEMU.

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

Notes:
    Version 2:
    - also translate blockers when fetching them from QEMU (in
      virQEMUCapsFetchCPUDefinitions)
    - rewritten commit message

 src/qemu/qemu_capabilities.c | 42 ++++++++++++++++++++++++++++++------
 src/qemu/qemu_capabilities.h |  4 ++++
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index ccd274b80d..6f3ff7f43f 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -2936,6 +2936,17 @@ virQEMUCapsFetchCPUDefinitions(qemuMonitor *mon,
         }
     }
 
+    for (i = 0; i < defs->ncpus; i++) {
+        qemuMonitorCPUDefInfo *cpu = &defs->cpus[i];
+        char **blocker;
+
+        if (!cpu->blockers)
+            continue;
+
+        for (blocker = cpu->blockers; *blocker; blocker++)
+            virQEMUCapsCPUFeatureFromQEMUInPlace(arch, blocker);
+    }
+
     *cpuDefs = g_steal_pointer(&defs);
     return 0;
 }
@@ -3483,6 +3494,19 @@ virQEMUCapsCPUFeatureFromQEMU(virArch arch,
 }
 
 
+void
+virQEMUCapsCPUFeatureFromQEMUInPlace(virArch arch,
+                                     char **feature)
+{
+    const char *tmp = virQEMUCapsCPUFeatureFromQEMU(arch, *feature);
+
+    if (tmp != *feature) {
+        VIR_FREE(*feature);
+        *feature = g_strdup(tmp);
+    }
+}
+
+
 /**
  * Returns  0 when host CPU model provided by QEMU was filled in qemuCaps,
  *          1 when the caller should fall back to using virCaps *->host.cpu,
@@ -3907,7 +3931,8 @@ virQEMUCapsLoadHostCPUModelInfo(virQEMUCapsAccel *caps,
 
 
 static int
-virQEMUCapsLoadCPUModels(virQEMUCapsAccel *caps,
+virQEMUCapsLoadCPUModels(virArch arch,
+                         virQEMUCapsAccel *caps,
                          xmlXPathContextPtr ctxt,
                          const char *typeStr)
 {
@@ -3978,6 +4003,8 @@ virQEMUCapsLoadCPUModels(virQEMUCapsAccel *caps,
                                      "capabilities cache"));
                     return -1;
                 }
+
+                virQEMUCapsCPUFeatureFromQEMUInPlace(arch, &cpu->blockers[j]);
             }
         }
 
@@ -4072,7 +4099,7 @@ virQEMUCapsLoadAccel(virQEMUCaps *qemuCaps,
     if (virQEMUCapsLoadHostCPUModelInfo(caps, ctxt, typeStr) < 0)
         return -1;
 
-    if (virQEMUCapsLoadCPUModels(caps, ctxt, typeStr) < 0)
+    if (virQEMUCapsLoadCPUModels(qemuCaps->arch, caps, ctxt, typeStr) < 0)
         return -1;
 
     if (virQEMUCapsLoadMachines(caps, ctxt, typeStr) < 0)
@@ -4534,7 +4561,8 @@ virQEMUCapsFormatHostCPUModelInfo(virQEMUCapsAccel *caps,
 
 
 static void
-virQEMUCapsFormatCPUModels(virQEMUCapsAccel *caps,
+virQEMUCapsFormatCPUModels(virArch arch,
+                           virQEMUCapsAccel *caps,
                            virBuffer *buf,
                            const char *typeStr)
 {
@@ -4563,8 +4591,10 @@ virQEMUCapsFormatCPUModels(virQEMUCapsAccel *caps,
             virBufferAddLit(buf, ">\n");
             virBufferAdjustIndent(buf, 2);
 
-            for (j = 0; cpu->blockers[j]; j++)
-                virBufferAsprintf(buf, "<blocker name='%s'/>\n", cpu->blockers[j]);
+            for (j = 0; cpu->blockers[j]; j++) {
+                virBufferAsprintf(buf, "<blocker name='%s'/>\n",
+                                  virQEMUCapsCPUFeatureToQEMU(arch, cpu->blockers[j]));
+            }
 
             virBufferAdjustIndent(buf, -2);
             virBufferAddLit(buf, "</cpu>\n");
@@ -4616,7 +4646,7 @@ virQEMUCapsFormatAccel(virQEMUCaps *qemuCaps,
     const char *typeStr = virQEMUCapsAccelStr(type);
 
     virQEMUCapsFormatHostCPUModelInfo(caps, buf, typeStr);
-    virQEMUCapsFormatCPUModels(caps, buf, typeStr);
+    virQEMUCapsFormatCPUModels(qemuCaps->arch, caps, buf, typeStr);
     virQEMUCapsFormatMachines(caps, buf, typeStr);
 
 }
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index 904ee54f60..4b2782c462 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -845,6 +845,10 @@ const char *
 virQEMUCapsCPUFeatureFromQEMU(virArch arch,
                               const char *feature);
 
+void
+virQEMUCapsCPUFeatureFromQEMUInPlace(virArch arch,
+                                     char **feature);
+
 virSEVCapability *
 virQEMUCapsGetSEVCapabilities(virQEMUCaps *qemuCaps);
 
-- 
2.38.0