[5/7] iommu/dma: Make limit checks self-contained

Commit Message

Robin Murphy Nov. 29, 2023, 5:43 p.m. UTC

It's now easy to retrieve the device's DMA limits if we want to check
them against the domain aperture, so do that ourselves instead of
relying on them being passed through the callchain.

Signed-off-by: Robin Murphy <[e-mail]>
---
 drivers/iommu/dma-iommu.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

Comments

Jason Gunthorpe Nov. 29, 2023, 8:43 p.m. UTC | #1

On Wed, Nov 29, 2023 at 05:43:02PM +0000, Robin Murphy wrote:
> It's now easy to retrieve the device's DMA limits if we want to check
> them against the domain aperture, so do that ourselves instead of
> relying on them being passed through the callchain.
> 
> Signed-off-by: Robin Murphy <[e-mail]>
> ---
>  drivers/iommu/dma-iommu.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)

When I spent some time noodling on this a few weeks ago I was looking
at putting the dma_range_map_min() effectively as a new reserved
region in the common reserved region code so it naturally flows out to
all the right places.

But this is no worse in that regard than what we have right now:

Reviewed-by: Jason Gunthorpe <[e-mail]>

>  	/* Check the domain allows at least some access to the device... */
> -	if (domain->geometry.force_aperture) {
> +	if (map) {

Oh, I've been sitting on a patch to delete force_aperture now too..

Jason

Patch

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5dc012220ca9..7745e7e17010 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -659,8 +659,6 @@  static void iommu_dma_init_options(struct iommu_dma_options *options,
 /**
  * iommu_dma_init_domain - Initialise a DMA mapping domain
  * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
- * @base: IOVA at which the mappable address space starts
- * @limit: Last address of the IOVA space
  * @dev: Device the domain is being initialised for
  *
  * @base and @limit + 1 should be exact multiples of IOMMU page granularity to
@@ -668,10 +666,10 @@  static void iommu_dma_init_options(struct iommu_dma_options *options,
  * to ensure it is an invalid IOVA. It is safe to reinitialise a domain, but
  * any change which could make prior IOVAs invalid will fail.
  */
-static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
-				 dma_addr_t limit, struct device *dev)
+static int iommu_dma_init_domain(struct iommu_domain *domain, struct device *dev)
 {
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	const struct bus_dma_region *map = dev->dma_range_map;
 	unsigned long order, base_pfn;
 	struct iova_domain *iovad;
 	int ret;
@@ -683,18 +681,18 @@  static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
 
 	/* Use the smallest supported page size for IOVA granularity */
 	order = __ffs(domain->pgsize_bitmap);
-	base_pfn = max_t(unsigned long, 1, base >> order);
+	base_pfn = 1;
 
 	/* Check the domain allows at least some access to the device... */
-	if (domain->geometry.force_aperture) {
+	if (map) {
+		dma_addr_t base = dma_range_map_min(map);
 		if (base > domain->geometry.aperture_end ||
-		    limit < domain->geometry.aperture_start) {
+		    dma_range_map_max(map) < domain->geometry.aperture_start) {
 			pr_warn("specified DMA range outside IOMMU capability\n");
 			return -EFAULT;
 		}
 		/* ...then finally give it a kicking to make sure it fits */
-		base_pfn = max_t(unsigned long, base_pfn,
-				domain->geometry.aperture_start >> order);
+		base_pfn = max(base, domain->geometry.aperture_start) >> order;
 	}
 
 	/* start_pfn is always nonzero for an already-initialised domain */
@@ -1743,7 +1741,7 @@  void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit)
 	 * underlying IOMMU driver needs to support via the dma-iommu layer.
 	 */
 	if (iommu_is_dma_domain(domain)) {
-		if (iommu_dma_init_domain(domain, dma_base, dma_limit, dev))
+		if (iommu_dma_init_domain(domain, dev))
 			goto out_err;
 		dev->dma_ops = &iommu_dma_ops;
 	}