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iommu/vt-d: Check capability before disabling protected memory

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[ Upstream commit 5bb71fc790a88d063507dc5d445ab8b14e845591 ]

The spec states in 10.4.16 that the Protected Memory Enable
Register should be treated as read-only for implementations
not supporting protected memory regions (PLMR and PHMR fields
reported as Clear in the Capability register).

Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: mark gross <mgross@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Fixes: f8bab73515ca5 ("intel-iommu: PMEN support")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Lu Baolu 2019-03-20 09:58:33 +08:00 committed by Greg Kroah-Hartman
parent 2e91bfe2a8
commit 41f08cc5a1
1 changed files with 3 additions and 0 deletions
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3
drivers/iommu/intel-iommu.c
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@ -1636,6 +1636,9 @@ static void iommu_disable_protect_mem_regions(struct intel_iommu *iommu)
u32 pmen;
unsigned long flags;
if (!cap_plmr(iommu->cap) && !cap_phmr(iommu->cap))
return;
raw_spin_lock_irqsave(&iommu->register_lock, flags);
pmen = readl(iommu->reg + DMAR_PMEN_REG);
pmen &= ~DMA_PMEN_EPM;