io/iommu: Add support to capture warn,alert,err,crit logs for specific keywords

Currently test fails for any test specific 'warn,alert,crit,err' dmesg
logs. But user may be interested for logs specific to iommu kernel driver.

This patch adds support to pass specific keywords for filtering the dmesg
logs to conclude pass or fail for the test.

Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>

Author: dhsrivas

io/iommu/iommu_tests.py

@@ -91,6 +91,7 @@ def setUp(self):
         self.pci_devices = self.params.get('pci_devices', default=None)
         self.count = int(self.params.get('count', default=1))
         self.domains = ["DMA", "DMA-FQ", "identity", "auto"]
+        self.dmesg_grep = self.params.get('dmesg_grep', default='')
         if not self.pci_devices:
             self.cancel("No pci device given")
         smm = SoftwareManager()
@@ -397,6 +398,8 @@ def check_dmesg(self):
         process.run(cmd, ignore_status=True, shell=True, sudo=True)
 
         cmd = "diff dmesg_final.txt dmesg_initial.txt"
+        if self.dmesg_grep != '':
+            cmd = f"{cmd} | grep -i -e '{self.dmesg_grep}'"
         dmesg_diff = process.run(cmd, ignore_status=True, shell=True, sudo=True).stdout_text
         if dmesg_diff != '':
             self.whiteboard = f"{dmesg_diff}"