[PATCH 4.19 048/110] iommu/vt-d: Check capability before disabling protected memory
From: Greg Kroah-Hartman
Date: Thu Apr 18 2019 - 14:00:12 EST
[ 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 2b8f5ebae821..603bf5233a99 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1624,6 +1624,9 @@ 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