provider/qemu_version: add qemu_version version_compare function

The qemu version is different, some scenes behave differently.
We need to distinguish and judge it, so add the qemu_version.version_compare().
Signed-off-by: NChen Qun <kuhn.chenqun@huawei.com>

provider/qemu_version.py

+"""
+Shared code for tests that need to get the qemu version
+"""
+
+import re
+import logging
+from avocado.utils import process
+from virttest.compat_52lts import decode_to_text as to_text
+
+QEMU_LIB_VERSION = 0
+
+
+def version_compare(major, minor, update):
+    """
+    Determine/use the current qemu library version on the system
+    and compare input major, minor, and update values against it.
+    If the running version is greater than or equal to the input
+    params version, then return True; otherwise, return False
+
+    This is designed to handle upstream version comparisons for
+    test adjustments and/or comparisons as a result of upstream
+    fixes or changes that could impact test results.
+
+    :param major: Major version to compare against
+    :param minor: Minor version to compare against
+    :param update: Update value to compare against
+    :return: True if running version is greater than or
+                  equal to the input qemu version
+    """
+    global QEMU_LIB_VERSION
+
+    if QEMU_LIB_VERSION == 0:
+        try:
+            regex = r'QEMU\s*emulator\s*version\s*(\d+)\.(\d+)\.(\d+)\s*'
+            check_cmd = "qemu-kvm -version"
+            lines = to_text(process.system_output(check_cmd))
+            mobj = re.search(regex, lines)
+            if bool(mobj):
+                QEMU_LIB_VERSION = int(mobj.group(1)) * 1000000 + \
+                    int(mobj.group(2)) * 1000 + \
+                    int(mobj.group(3))
+        except (ValueError, TypeError, AttributeError):
+            logging.warning("Error determining qemu version")
+            return False
+
+    compare_version = major * 1000000 + minor * 1000 + update
+
+    if QEMU_LIB_VERSION >= compare_version:
+        return True
+    return False