[RFC v2 1/3] vfio: VFIO_IOMMU_CACHE_INVALIDATE

[Liu Yi L <yi.l.liu@xxxxxxxxx>]

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.

Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/vfio/vfio_iommu_type1.c | 55 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       | 13 ++++++++++
 2 files changed, 68 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 96fddc1d..cd8d3a5 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -124,6 +124,34 @@ struct vfio_regions {
 #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
 					(!list_empty(&iommu->domain_list))
 
+struct domain_capsule {
+	struct iommu_domain *domain;
+	void *data;
+};
+
+/* iommu->lock must be held */
+static int
+vfio_iommu_lookup_dev(struct vfio_iommu *iommu,
+		      int (*fn)(struct device *dev, void *data),
+		      void *data)
+{
+	struct domain_capsule dc = {.data = data};
+	struct vfio_domain *d;
+	struct vfio_group *g;
+	int ret = 0;
+
+	list_for_each_entry(d, &iommu->domain_list, next) {
+		dc.domain = d->domain;
+		list_for_each_entry(g, &d->group_list, next) {
+			ret = iommu_group_for_each_dev(g->iommu_group,
+						       &dc, fn);
+			if (ret)
+				break;
+		}
+	}
+	return ret;
+}
+
 static int put_pfn(unsigned long pfn, int prot);
 
 /*
@@ -2211,6 +2239,15 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
 	return ret;
 }
 
+static int vfio_cache_inv_fn(struct device *dev, void *data)
+{
+	struct domain_capsule *dc = (struct domain_capsule *)data;
+	struct vfio_iommu_type1_cache_invalidate *ustruct =
+		(struct vfio_iommu_type1_cache_invalidate *)dc->data;
+
+	return iommu_cache_invalidate(dc->domain, dev, &ustruct->info);
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
 				   unsigned int cmd, unsigned long arg)
 {
@@ -2315,6 +2352,24 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 
 		return copy_to_user((void __user *)arg, &unmap, minsz) ?
 			-EFAULT : 0;
+	} 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_lookup_dev(iommu, vfio_cache_inv_fn,
+					    &ustruct);
+		mutex_unlock(&iommu->lock);
+		return ret;
 	}
 
 	return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9e843a1..ccf60a2 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -794,6 +794,19 @@ struct vfio_iommu_type1_dma_unmap {
 #define VFIO_IOMMU_ENABLE	_IO(VFIO_TYPE, VFIO_BASE + 15)
 #define VFIO_IOMMU_DISABLE	_IO(VFIO_TYPE, VFIO_BASE + 16)
 
+/**
+ * VFIO_IOMMU_CACHE_INVALIDATE - _IOWR(VFIO_TYPE, VFIO_BASE + 24,
+ *			struct vfio_iommu_type1_cache_invalidate)
+ *
+ * Propagate guest IOMMU cache invalidation to the host.
+ */
+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 + 24)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.4