[libvirt] [PATCH v1 1/4] qemu: place qemuCaps host cpu model in virCaps

[Collin Walling]

Some architectures retrieve their host CPU model data from QEMU
via qmp-query-cpu-model-expansion and stores it in the QEMU cache
files. Let's take this data and also store it in virCaps so we
can easily retrieve the host CPU model for later use.

We should also take care to ensure that we always query the same
cache file consistently between libvirtd executions, so let's
query the qemuCaps from the first qemu-system-ARCH found in $PATH
(via virQEMUCapsCacheLookup).

Signed-off-by: Collin Walling <walling at linux.ibm.com>
---
 src/qemu/qemu_capabilities.c | 53 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index cb716ff..d2eb813 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -896,6 +896,54 @@ virQEMUCapsProbeHostCPUForEmulator(virArch hostArch,
 }
 
 
+static int
+virQEMUProbeHostCPUModelFromBinary(virFileCachePtr cache,
+                                   virArch hostarch,
+                                   virCPUDefPtr *hostCPU)
+{
+    char *binary;
+    virQEMUCapsPtr qemuCaps = NULL;
+    virCPUDefPtr qemuCpu;
+    virCPUDefPtr tmp = NULL;
+    int ret = -1;
+
+    if (!(binary = virQEMUCapsFindBinaryForArch(hostarch, hostarch)))
+        goto cleanup;
+
+    if (!(qemuCaps = virQEMUCapsCacheLookup(cache, binary)))
+        goto cleanup;
+
+    /* If QEMU does not report the host's cpu model, then fail gracefully */
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION)) {
+        ret = 0;
+        goto cleanup;
+    }
+
+    if (!(qemuCpu = virQEMUCapsGetHostModel(qemuCaps, VIR_DOMAIN_VIRT_KVM,
+                                            VIR_QEMU_CAPS_HOST_CPU_REPORTED)))
+        goto cleanup;
+
+    if (VIR_ALLOC(tmp) < 0)
+        goto cleanup;
+
+    if (!(tmp = virCPUDefCopyWithoutModel(*hostCPU)))
+        goto cleanup;
+
+    if (virCPUDefCopyModel(tmp, qemuCpu, false) < 0)
+        goto cleanup;
+
+    virCPUDefFree(*hostCPU);
+    VIR_STEAL_PTR(*hostCPU, tmp);
+    ret = 0;
+
+ cleanup:
+    VIR_FREE(binary);
+    virCPUDefFree(tmp);
+    virObjectUnref(qemuCaps);
+    return ret;
+}
+
+
 virCapsPtr
 virQEMUCapsInit(virFileCachePtr cache)
 {
@@ -922,6 +970,11 @@ virQEMUCapsInit(virFileCachePtr cache)
     if (!(caps->host.cpu = virCPUProbeHost(caps->host.arch)))
         VIR_WARN("Failed to get host CPU");
 
+    /* Some archs get host cpu information via QEMU */
+    if (caps->host.cpu && !caps->host.cpu->model &&
+        virQEMUProbeHostCPUModelFromBinary(cache, hostarch, &caps->host.cpu) < 0)
+        VIR_WARN("Failed to get host CPU model from QEMU");
+
     /* Add the power management features of the host */
     if (virNodeSuspendGetTargetMask(&caps->host.powerMgmt) < 0)
         VIR_WARN("Failed to get host power management capabilities");
-- 
2.7.4