Andreas Sandberg has uploaded this change for review. (
https://gem5-review.googlesource.com/2580
Change subject: dev: Align BAR0 size to power of 2 for VirtIO devices
......................................................................
dev: Align BAR0 size to power of 2 for VirtIO devices
When setting the size of a PCI BAR, the kernel only supports powers of
two (as per the PCI spec). Previously, the size was incorrectly read
by the kernel, and the address ranges assigned to the PCI devices
could overlap, resulting in gem5 crashes. We now round up to the next
power of two.
Kudos to Sergei Trofimov who helped to debug this issue!
Change-Id: I54ca399b62ea07c09d4cd989b17dfa670e841bbe
Reviewed-by: Anouk Van Laer <[email protected]>
Reviewed-by: Sergei Trofimov <[email protected]>
Signed-off-by: Andreas Sandberg <[email protected]>
---
M src/base/bitfield.hh
M src/dev/virtio/pci.cc
2 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh
index 64f192f..885b422 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 @@
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 d8ec4f5..783b43e 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 @@
{
// 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);
}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I54ca399b62ea07c09d4cd989b17dfa670e841bbe
Gerrit-Change-Number: 2580
Gerrit-PatchSet: 1
Gerrit-Owner: Andreas Sandberg <[email protected]>
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