[RFC v3 05/21] vfio: VFIO_IOMMU_CACHE_INVALIDATE

[Eric Auger]

From: "Liu, Yi L" <yi.l.liu@xxxxxxxxxxxxxxx>

When the guest "owns" the stage 1 translation structures,  the host
IOMMU driver has no knowledge of caching structure updates unless
the guest invalidation requests are trapped and passed down to the
host.

This patch adds the VFIO_IOMMU_CACHE_INVALIDATE ioctl with aims
at propagating guest stage1 IOMMU cache invalidations to the host.

Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>

---

v2 -> v3:
- introduce vfio_iommu_for_each_dev back in this patch

v1 -> v2:
- s/TLB/CACHE
- remove vfio_iommu_task usage
- commit message rewording
---
 drivers/vfio/vfio_iommu_type1.c | 47 +++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  7 +++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index d9dd23f64f00..c3ba3f249438 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -113,6 +113,26 @@ struct vfio_regions {
 #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
 					(!list_empty(&iommu->domain_list))
 
+/* iommu->lock must be held */
+static int
+vfio_iommu_for_each_dev(struct vfio_iommu *iommu, void *data,
+			int (*fn)(struct device *, void *))
+{
+	struct vfio_domain *d;
+	struct vfio_group *g;
+	int ret = 0;
+
+	list_for_each_entry(d, &iommu->domain_list, next) {
+		list_for_each_entry(g, &d->group_list, next) {
+			ret = iommu_group_for_each_dev(g->iommu_group,
+						       data, fn);
+			if (ret)
+				break;
+		}
+	}
+	return ret;
+}
+
 static int put_pfn(unsigned long pfn, int prot);
 
 /*
@@ -1644,6 +1664,15 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
 	return ret;
 }
 
+static int vfio_cache_inv_fn(struct device *dev, void *data)
+{
+	struct vfio_iommu_type1_cache_invalidate *ustruct =
+		(struct vfio_iommu_type1_cache_invalidate *)data;
+	struct iommu_domain *d = iommu_get_domain_for_dev(dev);
+
+	return iommu_cache_invalidate(d, dev, &ustruct->info);
+}
+
 static int
 vfio_set_pasid_table(struct vfio_iommu *iommu,
 		      struct vfio_iommu_type1_set_pasid_table *ustruct)
@@ -1745,6 +1774,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 			return -EINVAL;
 
 		return vfio_set_pasid_table(iommu, &ustruct);
+	} else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
+		struct vfio_iommu_type1_cache_invalidate ustruct;
+		int ret;
+
+		minsz = offsetofend(struct vfio_iommu_type1_cache_invalidate,
+				    info);
+
+		if (copy_from_user(&ustruct, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (ustruct.argsz < minsz || ustruct.flags)
+			return -EINVAL;
+
+		mutex_lock(&iommu->lock);
+		ret = vfio_iommu_for_each_dev(iommu, &ustruct,
+					      vfio_cache_inv_fn);
+		mutex_unlock(&iommu->lock);
+		return ret;
 	}
 
 	return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 0d9f4090c95d..11a07165e7e1 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -767,6 +767,13 @@ struct vfio_iommu_type1_set_pasid_table {
 };
 #define VFIO_IOMMU_SET_PASID_TABLE	_IO(VFIO_TYPE, VFIO_BASE + 22)
 
+struct vfio_iommu_type1_cache_invalidate {
+	__u32   argsz;
+	__u32   flags;
+	struct iommu_cache_invalidate_info info;
+};
+#define VFIO_IOMMU_CACHE_INVALIDATE      _IO(VFIO_TYPE, VFIO_BASE + 23)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.17.2