Introduce virConnectCompareHypervisorCPU public API

This new API compares the given CPU description with the CPU the
specified hypervisor is able to provide on the host. It is a more useful
version of virConnectCompareCPU, which compares the CPU definition with
the host CPU without considering any specific hypervisor and its
abilities.

https://bugzilla.redhat.com/show_bug.cgi?id=1559832
https://bugzilla.redhat.com/show_bug.cgi?id=1559835

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Collin Walling <walling@linux.ibm.com>

include/libvirt/libvirt-host.h

@@ -640,6 +640,13 @@ typedef enum {
 int virConnectCompareCPU(virConnectPtr conn,
                          const char *xmlDesc,
                          unsigned int flags);
+int virConnectCompareHypervisorCPU(virConnectPtr conn,
+                                   const char *emulator,
+                                   const char *arch,
+                                   const char *machine,
+                                   const char *virttype,
+                                   const char *xmlCPU,
+                                   unsigned int flags);
 
 int virConnectGetCPUModelNames(virConnectPtr conn,
                                const char *arch,

src/driver-hypervisor.h

@@ -678,6 +678,15 @@ typedef int
                            const char *cpu,
                            unsigned int flags);
 
+typedef int
+(*virDrvConnectCompareHypervisorCPU)(virConnectPtr conn,
+                                     const char *emulator,
+                                     const char *arch,
+                                     const char *machine,
+                                     const char *virttype,
+                                     const char *xmlCPU,
+                                     unsigned int flags);
+
 typedef char *
 (*virDrvConnectBaselineCPU)(virConnectPtr conn,
                             const char **xmlCPUs,
@@ -1538,6 +1547,7 @@ struct _virHypervisorDriver {
     virDrvDomainSetVcpu domainSetVcpu;
     virDrvDomainSetBlockThreshold domainSetBlockThreshold;
     virDrvDomainSetLifecycleAction domainSetLifecycleAction;
+    virDrvConnectCompareHypervisorCPU connectCompareHypervisorCPU;
 };
 
 

src/libvirt-host.c

@@ -954,7 +954,11 @@ virConnectIsSecure(virConnectPtr conn)
  * @xmlDesc: XML describing the CPU to compare with host CPU
  * @flags: bitwise-OR of virConnectCompareCPUFlags
  *
- * Compares the given CPU description with the host CPU
+ * Compares the given CPU description with the host CPU.
+ *
+ * See virConnectCompareHypervisorCPU() if you want to consider hypervisor
+ * abilities and compare the CPU to the CPU which a hypervisor is able to
+ * provide on the host.
  *
  * Returns comparison result according to enum virCPUCompareResult. If
  * VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE is used and @xmlDesc CPU is
@@ -992,6 +996,72 @@ virConnectCompareCPU(virConnectPtr conn,
 }
 
 
+/**
+ * virConnectCompareHypervisorCPU:
+ * @conn: pointer to the hypervisor connection
+ * @emulator: path to the emulator binary
+ * @arch: CPU architecture
+ * @machine: machine type
+ * @virttype: virtualization type
+ * @xmlCPU: XML describing the CPU to be compared
+ * @flags: bitwise-OR of virConnectCompareCPUFlags
+ *
+ * Compares the given CPU description with the CPU the specified hypervisor is
+ * able to provide on the host. Any of @emulator, @arch, @machine, and
+ * @virttype parameters may be NULL; libvirt will choose sensible defaults
+ * tailored to the host and its current configuration.
+ *
+ * This is different from virConnectCompareCPU() which compares the CPU
+ * definition with the host CPU without considering any specific hypervisor and
+ * its abilities.
+ *
+ * Returns comparison result according to enum virCPUCompareResult. If
+ * VIR_CONNECT_COMPARE_CPU_FAIL_INCOMPATIBLE is used and @xmlCPU is
+ * incompatible with the CPU the specified hypervisor is able to provide on the
+ * host, this function will return VIR_CPU_COMPARE_ERROR (instead of
+ * VIR_CPU_COMPARE_INCOMPATIBLE) and the error will use the
+ * VIR_ERR_CPU_INCOMPATIBLE code with a message providing more details about
+ * the incompatibility.
+ */
+int
+virConnectCompareHypervisorCPU(virConnectPtr conn,
+                               const char *emulator,
+                               const char *arch,
+                               const char *machine,
+                               const char *virttype,
+                               const char *xmlCPU,
+                               unsigned int flags)
+{
+    VIR_DEBUG("conn=%p, emulator=%s, arch=%s, machine=%s, "
+              "virttype=%s, xmlCPU=%s, flags=0x%x",
+              conn, NULLSTR(emulator), NULLSTR(arch), NULLSTR(machine),
+              NULLSTR(virttype), NULLSTR(xmlCPU), flags);
+
+    virResetLastError();
+
+    virCheckConnectReturn(conn, VIR_CPU_COMPARE_ERROR);
+    virCheckNonNullArgGoto(xmlCPU, error);
+
+    if (conn->driver->connectCompareHypervisorCPU) {
+        int ret;
+
+        ret = conn->driver->connectCompareHypervisorCPU(conn, emulator, arch,
+                                                        machine, virttype,
+                                                        xmlCPU, flags);
+        if (ret == VIR_CPU_COMPARE_ERROR)
+            goto error;
+
+        return ret;
+    }
+
+    virReportUnsupportedError();
+
+ error:
+    virDispatchError(conn);
+    return VIR_CPU_COMPARE_ERROR;
+}
+
+
 /**
  * virConnectGetCPUModelNames:
  *

src/libvirt_public.syms

@@ -788,6 +788,7 @@ LIBVIRT_4.1.0 {
 LIBVIRT_4.4.0 {
     global:
         virDomainDetachDeviceAlias;
+        virConnectCompareHypervisorCPU;
 } LIBVIRT_4.1.0;
 
 # .... define new API here using predicted next version number ....