2 files changed, 45 insertions, 2 deletions

diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh
index 64f192f6d..885b42288 100644
--- a/src/base/bitfield.hh
+++ b/src/base/bitfield.hh
@@ -1,4 +1,16 @@
 /*
+ * Copyright (c) 2017 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
  * Copyright (c) 2003-2005 The Regents of The University of Michigan
  * All rights reserved.
  *
@@ -211,4 +223,29 @@ popCount(uint64_t val) {
     return (val * sum) >> 56;             // horizontal sum
 #endif // defined(__GNUC__) || (defined(__clang__) && __has_builtin(__builtin_popcountl))
 }
+
+/**
+ * Align to the next highest power of two.
+ *
+ * The number passed in is aligned to the next highest power of two,
+ * if it is not already a power of two. Please note that if 0 is
+ * passed in, 0 is returned.
+ *
+ * This code has been modified from the following:
+ * http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+ */
+inline uint64_t alignToPowerOfTwo(uint64_t val)
+{
+    val--;
+    val |= val >> 1;
+    val |= val >> 2;
+    val |= val >> 4;
+    val |= val >> 8;
+    val |= val >> 16;
+    val |= val >> 32;
+    val++;
+
+    return val;
+};
+
 #endif // __BASE_BITFIELD_HH__
diff --git a/src/dev/virtio/pci.cc b/src/dev/virtio/pci.cc
index d8ec4f5f8..783b43e65 100644
--- a/src/dev/virtio/pci.cc
+++ b/src/dev/virtio/pci.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 ARM Limited
+ * Copyright (c) 2014, 2017 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -39,6 +39,7 @@
 
 #include "dev/virtio/pci.hh"
 
+#include "base/bitfield.hh"
 #include "debug/VIOIface.hh"
 #include "mem/packet_access.hh"
 #include "params/PciVirtIO.hh"
@@ -49,7 +50,12 @@ PciVirtIO::PciVirtIO(const Params *params)
 {
     // Override the subsystem ID with the device ID from VirtIO
     config.subsystemID = htole(vio.deviceId);
-    BARSize[0] = BAR0_SIZE_BASE + vio.configSize;
+
+    // The kernel driver expects the BAR size to be an exact power of
+    // two. Nothing else is supported. Therefore, we need to force
+    // that alignment here. We do not touch vio.configSize as this is
+    // used to check accesses later on.
+    BARSize[0] = alignToPowerOfTwo(BAR0_SIZE_BASE + vio.configSize);
 
     vio.registerKickCallback(&callbackKick);
 }