[RFC v2 05/20] 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>

---

v1 -> v2:
- s/TLB/CACHE
- remove vfio_iommu_task usage
- commit message rewording
---
 drivers/vfio/vfio_iommu_type1.c | 44 +++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  7 ++++++
 2 files changed, 51 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 044d3a046125..14529233f774 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1673,6 +1673,37 @@ 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_cache_invalidate(struct vfio_iommu *iommu,
+		      struct vfio_iommu_type1_cache_invalidate *ustruct)
+{
+	struct vfio_domain *d;
+	struct vfio_group *g;
+	int ret = 0;
+
+	mutex_lock(&iommu->lock);
+
+	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, ustruct,
+						       vfio_cache_inv_fn);
+			if (ret)
+				break;
+		}
+	}
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
 static int
 vfio_bind_pasid_table(struct vfio_iommu *iommu,
 		      struct vfio_iommu_type1_bind_pasid_table *ustruct)
@@ -1774,6 +1805,19 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 			return -EINVAL;
 
 		return vfio_bind_pasid_table(iommu, &ustruct);
+	} else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
+		struct vfio_iommu_type1_cache_invalidate ustruct;
+
+		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;
+
+		return vfio_cache_invalidate(iommu, &ustruct);
 	}
 
 	return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index f81ce0a75c01..2a38d0bca0ca 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -673,6 +673,13 @@ struct vfio_iommu_type1_bind_pasid_table {
 };
 #define VFIO_IOMMU_BIND_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 -------- */
 
 /*
-- 
2.17.1