X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=drivers%2Fvfio%2Fvfio_iommu_type1.c;h=59d47cb638d5d18aac6700157ecc9be918772f91;hb=04527fdafe2e12ad2d89bfd0f0bb7fe481687976;hp=57d8c37a002b0e0b8d49891536b8ddfab64afc6b;hpb=9e441639d1ed78245600191f0fa45e106935a9dc;p=firefly-linux-kernel-4.4.55.git

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 57d8c37a002b..59d47cb638d5 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -403,13 +403,26 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
 static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
 {
 	struct vfio_domain *domain;
-	unsigned long bitmap = PAGE_MASK;
+	unsigned long bitmap = ULONG_MAX;
 
 	mutex_lock(&iommu->lock);
 	list_for_each_entry(domain, &iommu->domain_list, next)
 		bitmap &= domain->domain->ops->pgsize_bitmap;
 	mutex_unlock(&iommu->lock);
 
+	/*
+	 * In case the IOMMU supports page sizes smaller than PAGE_SIZE
+	 * we pretend PAGE_SIZE is supported and hide sub-PAGE_SIZE sizes.
+	 * That way the user will be able to map/unmap buffers whose size/
+	 * start address is aligned with PAGE_SIZE. Pinning code uses that
+	 * granularity while iommu driver can use the sub-PAGE_SIZE size
+	 * to map the buffer.
+	 */
+	if (bitmap & ~PAGE_MASK) {
+		bitmap &= PAGE_MASK;
+		bitmap |= PAGE_SIZE;
+	}
+
 	return bitmap;
 }