config_tools: board_inspector: fix MSR reads and writes

The MSR reading and writing routines today has the following issues:

  1. The missing of /dev/cpu/*/msr is not properly captured as it is
     reported via FileNotFoundError rather than IOError.

  2. The wrmsr logic is not updated to use the tmpdevfs msr file.

This patch fixes the issues above which is a prerequisite of adding
additional MSR parsing classes.

Tracked-On: #7948
Signed-off-by: Junjie Mao <junjie.mao@intel.com>

misc/config_tools/board_inspector/cpuparser/platformbase.py

@@ -139,11 +139,11 @@ class MSR(object):
     @classmethod
     def rdmsr(cls, cpu_id: int) -> int:
         try:
-            with open(f'/dev/cpu/{cpu_id}/msr', 'rb') as msr_reader:
+            with open(f'/dev/cpu/{cpu_id}/msr', 'rb', buffering=0) as msr_reader:
                 msr_reader.seek(cls.addr)
                 r = msr_reader.read(8)
                 r = cls(int.from_bytes(r, 'little'))
-        except IOError:
+        except FileNotFoundError:
             logging.critical(f"Missing CPU MSR file at /dev/cpu/{cpu_id}/msr. Check the value of CONFIG_X86_MSR " \
                              "in the kernel config.  Set it to 'Y' and rebuild the kernel. Then rerun the Board Inspector.")
             sys.exit(1)
@@ -154,7 +154,14 @@ class MSR(object):
     def wrmsr(self, cpu_id=None):
         if cpu_id is None:
             cpu_id = self.cpu_id
-        bits.wrmsr(cpu_id, self.addr, self.value)
+        try:
+            with open(f'/dev/cpu/{cpu_id}/msr', 'wb', buffering=0) as msr_reader:
+                msr_reader.seek(self.addr)
+                r = msr_reader.write(int.to_bytes(self.value, 8, 'little'))
+        except FileNotFoundError:
+            logging.critical(f"Missing CPU MSR file at /dev/cpu/{cpu_id}/msr. Check the value of CONFIG_X86_MSR " \
+                             "in the kernel config.  Set it to 'Y' and rebuild the kernel. Then rerun the Board Inspector.")
+            sys.exit(1)
 
     def __str__(self):
         T = type(self)