Upgraded firmware on mellanox infiniband connectx hardware and got following spam in system log.

[ 1680.962538] DRHD: handling fault status reg 302
[ 1680.967048] DMAR:[DMA Read] Request device [04:00.6] fault addr f647a000 
[ 1680.967049] DMAR:[fault reason 02] Present bit in context entry is clear

This also broke infiniband on f13/f14 machines.  I used the iommu workaround described above, and infiniband now works.

RHEL6.0 doesn't exhibit this problem with the updated firmware:

Linux mrg-03.mpc.lab.eng.bos.redhat.com 2.6.32-131.0.15.el6.x86_64 #1 SMP Tue Mx

Is this a kernel.org regression?

lspci results:
[root@mrg-04 ~]# lspci
00:00.0 Host bridge: Intel Corporation 5520 I/O Hub to ESI Port (rev 13)
00:01.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Po)
00:03.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Po)
00:04.0 PCI bridge: Intel Corporation 5520/X58 I/O Hub PCI Express Root Port 4 )
00:05.0 PCI bridge: Intel Corporation 5520/X58 I/O Hub PCI Express Root Port 5 )
00:06.0 PCI bridge: Intel Corporation 5520/X58 I/O Hub PCI Express Root Port 6 )
00:07.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Po)
00:09.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Po)
00:14.0 PIC: Intel Corporation 5520/5500/X58 I/O Hub System Management Register)
00:14.1 PIC: Intel Corporation 5520/5500/X58 I/O Hub GPIO and Scratch Pad Regis)
00:14.2 PIC: Intel Corporation 5520/5500/X58 I/O Hub Control Status and RAS Reg)
00:1a.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Control)
00:1a.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Control)
00:1a.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Contro)
00:1d.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Control)
00:1d.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Control)
00:1d.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Contro)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 92)
00:1f.0 ISA bridge: Intel Corporation 82801IB (ICH9) LPC Interface Controller ()
00:1f.2 IDE interface: Intel Corporation 82801IB (ICH9) 2 port SATA IDE Control)
01:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit )
01:00.1 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit )
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit )
02:00.1 Ethernet controller: Broadcom Corporation NetXtreme II BCM5709 Gigabit )
03:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 0)
04:00.0 InfiniBand: Mellanox Technologies MT26428 [ConnectX VPI PCIe 2.0 5GT/s )
08:03.0 VGA compatible controller: Matrox Graphics, Inc. MGA G200eW WPCM450 (re)
fe:00.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture)
fe:00.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture)
fe:02.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 0 (rev 05)
fe:02.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 0 (rev 05)
fe:02.4 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 1 (rev 05)
fe:02.5 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 1 (rev 05)
fe:03.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:03.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:03.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:03.4 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:04.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:04.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:04.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:04.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:05.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:05.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:05.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:05.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:06.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:06.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:06.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
fe:06.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:00.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture)
ff:00.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture)
ff:02.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 0 (rev 05)
ff:02.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 0 (rev 05)
ff:02.4 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 1 (rev 05)
ff:02.5 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 1 (rev 05)
ff:03.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:03.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:03.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:03.4 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:04.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:04.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:04.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:04.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:05.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:05.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:05.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:05.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:06.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:06.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:06.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
ff:06.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Cont)
[root@mrg-04 ~]#