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>

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8c7bb9befdab574622af413f68d555d6822a9cfa..1f90344d3e2c11bd47816ae7a54012b62bd3238f 100644 (file)
--- 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;
                }

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 460fdf2e26f10864a981b7ad08d6449fb5569c06..cb9023d4f06361cc77785cf86fc005c405bfdb27 100644 (file)
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -24,6 +24,11 @@
 #define VFIO_TYPE1_IOMMU               1
 #define VFIO_SPAPR_TCE_IOMMU           2
 #define VFIO_TYPE1v2_IOMMU             3
+/*
+ * IOMMU enforces DMA cache coherence (ex. PCIe NoSnoop stripping).  This
+ * capability is subject to change as groups are added or removed.
+ */
+#define VFIO_DMA_CC_IOMMU              4
 
 /*
  * The IOCTL interface is designed for extensibility by embedding the