[PATCH v11 1/8] iommu: Add iommu_domain_msi_geometry and DOMAIN_ATTR_MSI_GEOMETRY

[Eric Auger]

Introduce a new DOMAIN_ATTR_MSI_GEOMETRY domain attribute. It enables
to query the aperture of the IOVA window dedicated to MSIs and
test whether the MSIs must be mapped with the IOMMU-MSI API.

x86 IOMMUs will typically expose an MSI aperture matching the 1MB
region [FEE0_0000h - FEF0_000h] corresponding to the the APIC
configuration space and no support of the IOMMU-MSI API.

On ARM, the support of the IOMMU-MSI API will be advertised. Aperture
will refect the setting performed with the IOMMU-MSI API.

A helper function is added to allow testing if the aperture is valid.

Signed-off-by: Eric Auger <eric.au...@redhat.com>
Suggested-by: Alex Williamson <alex.william...@redhat.com>

---
v8 -> v9:
- rename programmable into iommu_msi_supported
- add iommu_domain_msi_aperture_valid

v8: creation
- deprecates DOMAIN_ATTR_MSI_MAPPING flag
---
 drivers/iommu/iommu.c |  5 +++++
 include/linux/iommu.h | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3000051..feab3cc 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1496,6 +1496,7 @@ int iommu_domain_get_attr(struct iommu_domain *domain,
                          enum iommu_attr attr, void *data)
 {
        struct iommu_domain_geometry *geometry;
+       struct iommu_domain_msi_geometry *msi_geometry;
        bool *paging;
        int ret = 0;
        u32 *count;
@@ -1506,6 +1507,10 @@ int iommu_domain_get_attr(struct iommu_domain *domain,
                *geometry = domain->geometry;
 
                break;
+       case DOMAIN_ATTR_MSI_GEOMETRY:
+               msi_geometry  = data;
+               *msi_geometry = domain->msi_geometry;
+               break;
        case DOMAIN_ATTR_PAGING:
                paging  = data;
                *paging = (domain->pgsize_bitmap != 0UL);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 664683a..1b553ee 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -52,6 +52,12 @@ struct iommu_domain_geometry {
        bool force_aperture;       /* DMA only allowed in mappable range? */
 };
 
+struct iommu_domain_msi_geometry {
+       dma_addr_t aperture_start; /* First address used for MSI IOVA    */
+       dma_addr_t aperture_end;   /* Last address used for MSI IOVA     */
+       bool iommu_msi_supported;  /* Is MSI mapping supported?          */
+};
+
 /* Domain feature flags */
 #define __IOMMU_DOMAIN_PAGING  (1U << 0)  /* Support for iommu_map/unmap */
 #define __IOMMU_DOMAIN_DMA_API (1U << 1)  /* Domain for use in DMA-API
@@ -83,6 +89,7 @@ struct iommu_domain {
        iommu_fault_handler_t handler;
        void *handler_token;
        struct iommu_domain_geometry geometry;
+       struct iommu_domain_msi_geometry msi_geometry;
        void *iova_cookie;
 };
 
@@ -108,6 +115,7 @@ enum iommu_cap {
 
 enum iommu_attr {
        DOMAIN_ATTR_GEOMETRY,
+       DOMAIN_ATTR_MSI_GEOMETRY,
        DOMAIN_ATTR_PAGING,
        DOMAIN_ATTR_WINDOWS,
        DOMAIN_ATTR_FSL_PAMU_STASH,
@@ -328,6 +336,12 @@ extern struct iommu_group *pci_device_group(struct device 
*dev);
 /* Generic device grouping function */
 extern struct iommu_group *generic_device_group(struct device *dev);
 
+static inline bool iommu_domain_msi_aperture_valid(struct iommu_domain *domain)
+{
+       return (domain->msi_geometry.aperture_end >
+               domain->msi_geometry.aperture_start);
+}
+
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
-- 
1.9.1

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