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| author | Tony Battersby <tonyb@cybernetics.com> | 2009-02-11 13:24:19 -0800 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2009-02-14 08:33:34 +0000 |
| commit | 084eb960e81505680a9963665722d1bfd94af6a7 (patch) | |
| tree | cfb6ed5b4449b4ae22b941529ece53ce0c705217 | |
| parent | 704126ad81b8cb7d3d70adb9ecb143f4d3fb38af (diff) | |
| download | op-kernel-dev-084eb960e81505680a9963665722d1bfd94af6a7.zip op-kernel-dev-084eb960e81505680a9963665722d1bfd94af6a7.tar.gz | |
intel-iommu: fix endless "Unknown DMAR structure type" loop
I have a SuperMicro C2SBX motherboard with BIOS revision 1.0b. With vt-d
enabled in the BIOS, Linux gets into an endless loop printing
"DMAR:Unknown DMAR structure type" when booting. Here is the DMAR ACPI
table:
DMAR @ 0x7fe86dec
0000: 44 4d 41 52 98 00 00 00 01 6f 49 6e 74 65 6c 20 DMAR.....oIntel
0010: 4f 45 4d 44 4d 41 52 20 00 00 04 06 4c 4f 48 52 OEMDMAR ....LOHR
0020: 01 00 00 00 23 00 00 00 00 00 00 00 00 00 00 00 ....#...........
0030: 01 00 58 00 00 00 00 00 00 a0 e8 7f 00 00 00 00 ..X.............
0040: ff ff ef 7f 00 00 00 00 01 08 00 00 00 00 1d 00 ................
0050: 01 08 00 00 00 00 1d 01 01 08 00 00 00 00 1d 02 ................
0060: 01 08 00 00 00 00 1d 07 01 08 00 00 00 00 1a 00 ................
0070: 01 08 00 00 00 00 1a 01 01 08 00 00 00 00 1a 02 ................
0080: 01 08 00 00 00 00 1a 07 01 08 00 00 00 00 1a 07 ................
0090: c0 00 68 00 04 10 66 60 ..h...f`
Here are the messages printed by the kernel:
DMAR:Host address width 36
DMAR:RMRR base: 0x000000007fe8a000 end: 0x000000007fefffff
DMAR:Unknown DMAR structure type
DMAR:Unknown DMAR structure type
DMAR:Unknown DMAR structure type
...
Although I not very familiar with ACPI, to me it looks like struct
acpi_dmar_header::length == 0x0058 is incorrect, causing
parse_dmar_table() to look at an invalid offset on the next loop. This
offset happens to have struct acpi_dmar_header::length == 0x0000, which
prevents the loop from ever terminating. This patch checks for this
condition and bails out instead of looping forever.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
| -rw-r--r-- | drivers/pci/dmar.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c index 8d3e9c2..26c536b 100644 --- a/drivers/pci/dmar.c +++ b/drivers/pci/dmar.c @@ -330,6 +330,14 @@ parse_dmar_table(void) entry_header = (struct acpi_dmar_header *)(dmar + 1); while (((unsigned long)entry_header) < (((unsigned long)dmar) + dmar_tbl->length)) { + /* Avoid looping forever on bad ACPI tables */ + if (entry_header->length == 0) { + printk(KERN_WARNING PREFIX + "Invalid 0-length structure\n"); + ret = -EINVAL; + break; + } + dmar_table_print_dmar_entry(entry_header); switch (entry_header->type) { |
