[PATCH v5 6/9] iommu/vt-d: Make first level IOVA canonical

Lu Baolu
2019-12-24T07:46:26Z

First-level translation restricts the input-address to a canonical
address (i.e., address bits 63:N have the same value as address
bit [N-1], where N is 48-bits with 4-level paging and 57-bits with
5-level paging). (section 3.6 in the spec)

This makes first level IOVA canonical by using IOVA with bit [N-1]
always cleared.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/intel-iommu.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 54db6bc0b281..1ebf5ed460cf 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3505,8 +3505,21 @@ static unsigned long intel_alloc_iova(struct device *dev,
{
unsigned long iova_pfn;

- /* Restrict dma_mask to the width that the iommu can handle */
- dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw), dma_mask);
+ /*
+ * Restrict dma_mask to the width that the iommu can handle.
+ * First-level translation restricts the input-address to a
+ * canonical address (i.e., address bits 63:N have the same
+ * value as address bit [N-1], where N is 48-bits with 4-level
+ * paging and 57-bits with 5-level paging). Hence, skip bit
+ * [N-1].
+ */
+ if (domain_use_first_level(domain))
+ dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw - 1),
+ dma_mask);
+ else
+ dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw),
+ dma_mask);
+
/* Ensure we reserve the whole size-aligned region */
nrpages = __roundup_pow_of_two(nrpages);