From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxxxx>
Cc: mark gross <mgross@xxxxxxxxx>
Suggested-by: Ashok Raj <ashok.raj@xxxxxxxxx>
Fixes: f8bab73515ca5 ("intel-iommu: PMEN support")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/iommu/intel-iommu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 8b4a4d95669a..3e97c4b2ebed 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1598,6 +1598,9 @@ 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;
--
2.19.1
