iommu: Make IOVA domain page size explicit

Systems may contain heterogeneous IOMMUs supporting differing minimum
page sizes, which may also not be common with the CPU page size.
Thus it is practical to have an explicit notion of IOVA granularity
to simplify handling of mapping and allocation constraints.

As an initial step, move the IOVA page granularity from an implicit
compile-time constant to a per-domain property so we can make use
of it in IOVA domain context at runtime. To keep the abstraction tidy,
extend the little API of inline iova_* helpers to parallel some of the
equivalent PAGE_* macros.

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

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 86f9e82b015b6041fa570250d5b68a2c9290b72c..ae4c1a854e57896fc64e33668369bebc23f70945 100644 (file)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1635,7 +1635,8 @@ static int dmar_init_reserved_ranges(void)
        struct iova *iova;
        int i;
 
-       init_iova_domain(&reserved_iova_list, IOVA_START_PFN, DMA_32BIT_PFN);
+       init_iova_domain(&reserved_iova_list, VTD_PAGE_SIZE, IOVA_START_PFN,
+                       DMA_32BIT_PFN);
 
        lockdep_set_class(&reserved_iova_list.iova_rbtree_lock,
                &reserved_rbtree_key);
@@ -1693,7 +1694,8 @@ static int domain_init(struct dmar_domain *domain, int guest_width)
        int adjust_width, agaw;
        unsigned long sagaw;
 
-       init_iova_domain(&domain->iovad, IOVA_START_PFN, DMA_32BIT_PFN);
+       init_iova_domain(&domain->iovad, VTD_PAGE_SIZE, IOVA_START_PFN,
+                       DMA_32BIT_PFN);
        domain_reserve_special_ranges(domain);
 
        /* calculate AGAW */
@@ -4316,7 +4318,8 @@ static int md_domain_init(struct dmar_domain *domain, int guest_width)
 {
        int adjust_width;
 
-       init_iova_domain(&domain->iovad, IOVA_START_PFN, DMA_32BIT_PFN);
+       init_iova_domain(&domain->iovad, VTD_PAGE_SIZE, IOVA_START_PFN,
+                       DMA_32BIT_PFN);
        domain_reserve_special_ranges(domain);
 
        /* calculate AGAW */

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index a3dbba8caa19f8a77d3031624b7d4f76a0674b7d..9dd8208312c2e75874ce70dcc6008a166eb5ffca 100644 (file)
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -55,12 +55,20 @@ void free_iova_mem(struct iova *iova)
 }
 
 void
-init_iova_domain(struct iova_domain *iovad, unsigned long start_pfn,
-       unsigned long pfn_32bit)
+init_iova_domain(struct iova_domain *iovad, unsigned long granule,
+       unsigned long start_pfn, unsigned long pfn_32bit)
 {
+       /*
+        * IOVA granularity will normally be equal to the smallest
+        * supported IOMMU page size; both *must* be capable of
+        * representing individual CPU pages exactly.
+        */
+       BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule));
+
        spin_lock_init(&iovad->iova_rbtree_lock);
        iovad->rbroot = RB_ROOT;
        iovad->cached32_node = NULL;
+       iovad->granule = granule;
        iovad->start_pfn = start_pfn;
        iovad->dma_32bit_pfn = pfn_32bit;
 }

diff --git a/include/linux/iova.h b/include/linux/iova.h
index 591b19626b4653b4bd391e68bc969107b54ec0ab..3920a19d819415bc3109a491171e32388f9bda18 100644 (file)
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -28,6 +28,7 @@ struct iova_domain {
        spinlock_t      iova_rbtree_lock; /* Lock to protect update of rbtree */
        struct rb_root  rbroot;         /* iova domain rbtree root */
        struct rb_node  *cached32_node; /* Save last alloced node */
+       unsigned long   granule;        /* pfn granularity for this domain */
        unsigned long   start_pfn;      /* Lower limit for this domain */
        unsigned long   dma_32bit_pfn;
 };
@@ -37,6 +38,36 @@ static inline unsigned long iova_size(struct iova *iova)
        return iova->pfn_hi - iova->pfn_lo + 1;
 }
 
+static inline unsigned long iova_shift(struct iova_domain *iovad)
+{
+       return __ffs(iovad->granule);
+}
+
+static inline unsigned long iova_mask(struct iova_domain *iovad)
+{
+       return iovad->granule - 1;
+}
+
+static inline size_t iova_offset(struct iova_domain *iovad, dma_addr_t iova)
+{
+       return iova & iova_mask(iovad);
+}
+
+static inline size_t iova_align(struct iova_domain *iovad, size_t size)
+{
+       return ALIGN(size, iovad->granule);
+}
+
+static inline dma_addr_t iova_dma_addr(struct iova_domain *iovad, struct iova *iova)
+{
+       return (dma_addr_t)iova->pfn_lo << iova_shift(iovad);
+}
+
+static inline unsigned long iova_pfn(struct iova_domain *iovad, dma_addr_t iova)
+{
+       return iova >> iova_shift(iovad);
+}
+
 int iommu_iova_cache_init(void);
 void iommu_iova_cache_destroy(void);
 
@@ -50,8 +81,8 @@ struct iova *alloc_iova(struct iova_domain *iovad, unsigned long size,
 struct iova *reserve_iova(struct iova_domain *iovad, unsigned long pfn_lo,
        unsigned long pfn_hi);
 void copy_reserved_iova(struct iova_domain *from, struct iova_domain *to);
-void init_iova_domain(struct iova_domain *iovad, unsigned long start_pfn,
-       unsigned long pfn_32bit);
+void init_iova_domain(struct iova_domain *iovad, unsigned long granule,
+       unsigned long start_pfn, unsigned long pfn_32bit);
 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn);
 void put_iova_domain(struct iova_domain *iovad);
 struct iova *split_and_remove_iova(struct iova_domain *iovad,