intel_iommu: disable all VT-d PMRs when TXT launched
Intel VT-d Protected Memory Regions (PMRs) are supposed to be disabled, on each VT-d engine, after DMA remapping is enabled on the engines. This is because the behavior of having both enabled is not deterministic and because, if TXT has been used to launch the kernel, the PMRs may be programmed to cover memory regions that will be used for DMA. Under some circumstances (certain quirks detected, lack of multiple devices, etc.), the current code does not set up DMA remapping on some VT-d engines. In such cases it also skips disabling the PMRs. This causes failures when the kernel is launched with TXT (most often this occurs on the graphics engine and results in colored vertical bars on the display). This patch detects when the kernel has been launched with TXT and then disables the PMRs on all VT-d engines. In some cases where the reason that remapping is not being enabled is due to possible ACPI DMAR table errors, the VT-d engine addresses may not be correct and thus not able to be safely programmed even to disable PMRs. Because part of the TXT launch process is the verification of these addresses, it will always be safe to disable PMRs if the TXT launch has succeeded and hence only doing this in such cases. Signed-off-by: NJoseph Cihula <joseph.cihula@intel.com> Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
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