From 2691f50bae8a6314f7ec0884ab3a8b83a02fdeb1 Mon Sep 17 00:00:00 2001
From: Gabriel Kerneis <gabriel.kerneis@ssi.gouv.fr>
Date: Wed, 11 Aug 2021 15:14:21 +0200
Subject: [PATCH] Detect PCH based on platform vendor ID

An alternative approach would be to use get_cpuid(eax=0) to recover the
vendor, but cpuid is only available when a driver is loaded. Assume that
there is always a PCI device 00:0.0 providing the correct vendor.

Currently supports AMD and Intel.

Bug: #825
Signed-off-by: Gabriel Kerneis <gabriel.kerneis@ssi.gouv.fr>
---
 chipsec/chipset.py | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/chipsec/chipset.py b/chipsec/chipset.py
index 87f43f0c..14a8da53 100644
--- a/chipsec/chipset.py
+++ b/chipsec/chipset.py
@@ -89,19 +89,19 @@ CHIPSET_FAMILY_QUARK = []
 
 PCH_CODE_PREFIX = 'PCH_'
 
+PCH_ADDRESS = {
+    # Intel: 0:1F.0
+    0x8086: (0, 0x1F, 0),
+    # AMD: 0:14.3
+    0x1022: (0, 0x14, 3)
+}
+
 try:
     from chipsec.custom_chipsets import *
 except ImportError:
     pass
 
 
-def f_xml(self, x):
-    XMLFILE_RE = re.compile("^\w+\.xml")
-    return ( x.find('common') == -1 and XMLFILE_RE.match(x) )
-def map_xmlname(self, x):
-    return x.split('.')[0]
-
-
 class Chipset:
 
     def __init__(self, helper=None):
@@ -167,13 +167,17 @@ class Chipset:
             rid = self.pci.read_byte(0, 0, 0, PCI_HDR_RID_OFF)
         except:
             if logger().DEBUG: logger().error("pci.read_dword couldn't read platform VID/DID")
-        try:
-            vid_did = self.pci.read_dword(0, 31, 0, 0)
-            pch_vid = vid_did & 0xFFFF
-            pch_did = (vid_did >> 16) & 0xFFFF
-            pch_rid = self.pci.read_byte(0, 31, 0, PCI_HDR_RID_OFF)
-        except:
-            if logger().DEBUG: logger().error("pci.read_dword couldn't read PCH VID/DID")
+        if not vid in PCH_ADDRESS:
+            if logger().DEBUG: logger().error("PCH address unknown for VID {}.".format(vid))
+        else:
+            try:
+                 (bus,dev,fun) = PCH_ADDRESS[vid]
+                 vid_did = self.pci.read_dword(bus, dev, fun, 0)
+                 pch_vid = vid_did & 0xFFFF
+                 pch_did = (vid_did >> 16) & 0xFFFF
+                 pch_rid = self.pci.read_byte(0, 31, 0, PCI_HDR_RID_OFF)
+            except:
+                 if logger().DEBUG: logger().error("pci.read_dword couldn't read PCH VID/DID")
         return (vid, did, rid, pch_vid, pch_did, pch_rid)
 
     def get_cpuid(self):