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@xxxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 21 +++++++++++++++++++++
include/uapi/linux/vfio.h | 5 +++++
2 files changed, 26 insertions(+)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8c7bb9b..1f90344 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;
}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 460fdf2..cb9023d 100644
--- 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
--
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