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Subject[PATCH v2] iommu/vt-d: respect max guest address width in agaw
Date
Supported guest address witdh (SGAW) only indicates
what the iommu's capabilities are wrt page table levels
for second level page-tables. IOMMU should pick the
right level depending on the Maximum Guest Address Width
(MGAW).

For pass-through translation type, address width must be
programmed with the largest AGAW supported by the HW.

Reported-by: Ramos Falcon, Ernesto R <ernesto.r.ramos.falcon@intel.com>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
drivers/iommu/intel-iommu.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 140d6ab..f16db3b 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -719,7 +719,11 @@ int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
*/
int iommu_calculate_agaw(struct intel_iommu *iommu)
{
- return __iommu_calculate_agaw(iommu, DEFAULT_DOMAIN_ADDRESS_WIDTH);
+ unsigned long mgaw;
+
+ /* Respect Max Guest Address Width */
+ mgaw = min(cap_mgaw(iommu->cap), DEFAULT_DOMAIN_ADDRESS_WIDTH);
+ return __iommu_calculate_agaw(iommu, mgaw);
}

/* This functionin only returns single iommu in a domain */
--
2.7.4
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