IOMMU fixes for Linux v3.8-rc5

One fix for the AMD IOMMU driver to work around broken BIOSes found in
the field. Some BIOSes forget to enable a workaround for a hardware
problem which might cause the IOMMU to stop working under high load
conditions. The fix makes sure this workaround is enabled.
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IOMMU, AMD Family15h Model10-1Fh erratum 746 Workaround

The IOMMU may stop processing page translations due to a perceived lack
of credits for writing upstream peripheral page service request (PPR)
or event logs. If the L2B miscellaneous clock gating feature is enabled
the IOMMU does not properly register credits after the log request has
completed, leading to a potential system hang.

BIOSes are supposed to disable L2B micellaneous clock gating by setting
L2_L2B_CK_GATE_CONTROL[CKGateL2BMiscDisable](D0F2xF4_x90[2]) = 1b. This
patch corrects that for those which do not enable this workaround.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Joerg Roedel <joro@8bytes.org>
1 file changed