iommu/core: split mapping to page sizes as supported by the hardware

When mapping a memory region, split it to page sizes as supported
by the iommu hardware. Always prefer bigger pages, when possible,
in order to reduce the TLB pressure.

The logic to do that is now added to the IOMMU core, so neither the iommu
drivers themselves nor users of the IOMMU API have to duplicate it.

This allows a more lenient granularity of mappings; traditionally the
IOMMU API took 'order' (of a page) as a mapping size, and directly let
the low level iommu drivers handle the mapping, but now that the IOMMU
core can split arbitrary memory regions into pages, we can remove this
limitation, so users don't have to split those regions by themselves.

Currently the supported page sizes are advertised once and they then
remain static. That works well for OMAP and MSM but it would probably
not fly well with intel's hardware, where the page size capabilities
seem to have the potential to be different between several DMA
remapping devices.

register_iommu() currently sets a default pgsize behavior, so we can convert
the IOMMU drivers in subsequent patches. After all the drivers
are converted, the temporary default settings will be removed.

Mainline users of the IOMMU API (kvm and omap-iovmm) are adopted
to deal with bytes instead of page order.

Many thanks to Joerg Roedel <Joerg.Roedel@amd.com> for significant review!

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Joerg Roedel <Joerg.Roedel@amd.com>
Cc: Stepan Moskovchenko <stepanm@codeaurora.org>
Cc: KyongHo Cho <pullip.cho@samsung.com>
Cc: Hiroshi DOYU <hdoyu@nvidia.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index d5ebf3f4dd53..cc26f89c4ee6 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -48,6 +48,19 @@ struct iommu_domain {
 
 #ifdef CONFIG_IOMMU_API
 
+/**
+ * struct iommu_ops - iommu ops and capabilities
+ * @domain_init: init iommu domain
+ * @domain_destroy: destroy iommu domain
+ * @attach_dev: attach device to an iommu domain
+ * @detach_dev: detach device from an iommu domain
+ * @map: map a physically contiguous memory region to an iommu domain
+ * @unmap: unmap a physically contiguous memory region from an iommu domain
+ * @iova_to_phys: translate iova to physical address
+ * @domain_has_cap: domain capabilities query
+ * @commit: commit iommu domain
+ * @pgsize_bitmap: bitmap of supported page sizes
+ */
 struct iommu_ops {
         int (*domain_init)(struct iommu_domain *domain);
         void (*domain_destroy)(struct iommu_domain *domain);
@@ -61,6 +74,7 @@ struct iommu_ops {
                                     unsigned long iova);
         int (*domain_has_cap)(struct iommu_domain *domain,
                               unsigned long cap);
+        unsigned long pgsize_bitmap;
 };
 
 extern int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
@@ -72,9 +86,9 @@ extern int iommu_attach_device(struct iommu_domain *domain,
 extern void iommu_detach_device(struct iommu_domain *domain,
                                 struct device *dev);
 extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
-                     phys_addr_t paddr, int gfp_order, int prot);
-extern int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
-                       int gfp_order);
+                     phys_addr_t paddr, size_t size, int prot);
+extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
+                       size_t size);
 extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
                                       unsigned long iova);
 extern int iommu_domain_has_cap(struct iommu_domain *domain,