vfio/type1: Add extension to test DMA cache coherence of IOMMU

Now that the type1 IOMMU backend can support IOMMU_CACHE, we need to
be able to test whether coherency is currently enforced.  Add an
extension for this.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8c7bb9befdab..1f90344d3e2c 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -867,6 +867,23 @@ static void vfio_iommu_type1_release(void *iommu_data)
         kfree(iommu);
 }
 
+static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
+{
+        struct vfio_domain *domain;
+        int ret = 1;
+
+        mutex_lock(&iommu->lock);
+        list_for_each_entry(domain, &iommu->domain_list, next) {
+                if (!(domain->prot & IOMMU_CACHE)) {
+                        ret = 0;
+                        break;
+                }
+        }
+        mutex_unlock(&iommu->lock);
+
+        return ret;
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
                                    unsigned int cmd, unsigned long arg)
 {
@@ -878,6 +895,10 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
                 case VFIO_TYPE1_IOMMU:
                 case VFIO_TYPE1v2_IOMMU:
                         return 1;
+                case VFIO_DMA_CC_IOMMU:
+                        if (!iommu)
+                                return 0;
+                        return vfio_domains_have_iommu_cache(iommu);
                 default:
                         return 0;
                 }