[RFC 03/11] iommu: Introduce IOMMU_DOMAIN_MIXED

[Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

We introduce a new IOMMU domain type, dubbed IOMMU_DOMAIN_MIXED.
It is bound to be used as a replacement of IOMMU_DOMAIN_UNMANAGED
when the IOMMU translates MSI addresses. Such domain hosts
"unmanaged" reserved IOVA ranges chosen by the iommu-api user,
dished out as part of alloc_iova. Rest if available for internal
iova needs such as MSI frame IOVA allocation.

Signed-off-by: Eric Auger <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 include/linux/iommu.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5c2673a..44fe213 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -62,6 +62,9 @@ struct iommu_domain_msi_geometry {
 #define __IOMMU_DOMAIN_DMA_API	(1U << 1)  /* Domain for use in DMA-API
 					      implementation              */
 #define __IOMMU_DOMAIN_PT	(1U << 2)  /* Domain is identity mapped   */
+#define __IOMMU_DOMAIN_MIXED	(1U << 3)  /* Domain mixing unmanaged and
+					    * managed IOVAS
+					    */
 
 /*
  * This are the possible domain-types
@@ -71,6 +74,9 @@ struct iommu_domain_msi_geometry {
  *	IOMMU_DOMAIN_IDENTITY	- DMA addresses are system physical addresses
  *	IOMMU_DOMAIN_UNMANAGED	- DMA mappings managed by IOMMU-API user, used
  *				  for VMs
+ *	IOMMU_DOMAIN_MIXED	- Most DMA mappings are managed by IOMMU-API
+ *				  users and holes are left available for
+				  internal use such as MSI frame IOVA allocation
  *	IOMMU_DOMAIN_DMA	- Internally used for DMA-API implementations.
  *				  This flag allows IOMMU drivers to implement
  *				  certain optimizations for these domains
@@ -80,6 +86,9 @@ struct iommu_domain_msi_geometry {
 #define IOMMU_DOMAIN_UNMANAGED	(__IOMMU_DOMAIN_PAGING)
 #define IOMMU_DOMAIN_DMA	(__IOMMU_DOMAIN_PAGING |	\
 				 __IOMMU_DOMAIN_DMA_API)
+#define IOMMU_DOMAIN_MIXED	(__IOMMU_DOMAIN_MIXED |		\
+				 __IOMMU_DOMAIN_PAGING |	\
+				 __IOMMU_DOMAIN_DMA_API)
 
 struct iommu_domain {
 	unsigned type;
-- 
1.9.1