iommu: Make IOVA domain low limit flexible

To share the IOVA allocator with other architectures, it needs to
accommodate more general aperture restrictions; move the lower limit
from a compile-time constant to a runtime domain property to allow
IOVA domains with different requirements to co-exist.

Also reword the slightly unclear description of alloc_iova since we're
touching it anyway.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e758d8ed8fb5..86f9e82b015b 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -71,6 +71,9 @@
                                 __DOMAIN_MAX_PFN(gaw), (unsigned long)-1))
 #define DOMAIN_MAX_ADDR(gaw)    (((uint64_t)__DOMAIN_MAX_PFN(gaw)) << VTD_PAGE_SHIFT)
 
+/* IO virtual address start page frame number */
+#define IOVA_START_PFN          (1)
+
 #define IOVA_PFN(addr)          ((addr) >> PAGE_SHIFT)
 #define DMA_32BIT_PFN           IOVA_PFN(DMA_BIT_MASK(32))
 #define DMA_64BIT_PFN           IOVA_PFN(DMA_BIT_MASK(64))
@@ -1632,7 +1635,7 @@ static int dmar_init_reserved_ranges(void)
         struct iova *iova;
         int i;
 
-        init_iova_domain(&reserved_iova_list, DMA_32BIT_PFN);
+        init_iova_domain(&reserved_iova_list, IOVA_START_PFN, DMA_32BIT_PFN);
 
         lockdep_set_class(&reserved_iova_list.iova_rbtree_lock,
                 &reserved_rbtree_key);
@@ -1690,7 +1693,7 @@ static int domain_init(struct dmar_domain *domain, int guest_width)
         int adjust_width, agaw;
         unsigned long sagaw;
 
-        init_iova_domain(&domain->iovad, DMA_32BIT_PFN);
+        init_iova_domain(&domain->iovad, IOVA_START_PFN, DMA_32BIT_PFN);
         domain_reserve_special_ranges(domain);
 
         /* calculate AGAW */
@@ -4313,7 +4316,7 @@ static int md_domain_init(struct dmar_domain *domain, int guest_width)
 {
         int adjust_width;
 
-        init_iova_domain(&domain->iovad, DMA_32BIT_PFN);
+        init_iova_domain(&domain->iovad, IOVA_START_PFN, DMA_32BIT_PFN);
         domain_reserve_special_ranges(domain);
 
         /* calculate AGAW */