D32591.id97214.diff
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D32591.id97214.diff
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	Index: sys/x86/iommu/intel_utils.c
	===================================================================
	--- sys/x86/iommu/intel_utils.c
	+++ sys/x86/iommu/intel_utils.c
	@@ -489,6 +489,33 @@
	return (error);
	}

	+/*
	+ * Some BIOSes protect memory region they reside in by using DMAR to
	+ * prevent devices from doing any DMA transactions to that part of RAM.
	+ * AMI refers to this as "DMA Control Guarantee".
	+ * We need to disable this right after address translation is enabled.
	+ */
	+static int
	+dmar_disable_protected_regions(struct dmar_unit *unit)
	+{
	+ uint32_t reg;
	+ int error;
	+
	+ DMAR_ASSERT_LOCKED(unit);
	+
	+ /* Check if we support the feature. */
	+ if (!(unit->hw_cap & (DMAR_CAP_PLMR \| DMAR_CAP_PHMR)))
	+ return (0);
	+
	+ reg = dmar_read4(unit, DMAR_PMEN_REG);
	+ reg &= ~DMAR_PMEN_EPM;
	+ dmar_write4(unit, DMAR_PMEN_REG, reg);
	+ DMAR_WAIT_UNTIL(((dmar_read4(unit, DMAR_PMEN_REG) & DMAR_PMEN_PRS)
	+ != 0));
	+
	+ return (error);
	+}
	+
	int
	dmar_enable_translation(struct dmar_unit *unit)
	{
	@@ -499,7 +526,10 @@
	dmar_write4(unit, DMAR_GCMD_REG, unit->hw_gcmd);
	DMAR_WAIT_UNTIL(((dmar_read4(unit, DMAR_GSTS_REG) & DMAR_GSTS_TES)
	!= 0));
	- return (error);
	+ if (error != 0)
	+ return (error);
	+
	+ return (dmar_disable_protected_regions(unit));
	}

	int