[RFC v3 7/8] vfio/type1: Add VFIO_IOMMU_CACHE_INVALIDATE

[Liu, Yi L]

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

For IOMMU with type VFIO_TYPE1_NESTING_IOMMU, guest "owns" the
first-level/stage-1 translation structures, the host IOMMU driver
has no knowledge of first-level/stage-1 structure cache 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 first-level/stage-1 IOMMU cache invalidations
to the host to keep IOMMU cache updated.

With this patch, vSVA (Virtual Shared Virtual Addressing) can be
used safely as the host IOMMU iotlb correctness are ensured.

Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Eric Auger <eric.auger@xxxxxxxxxx>
Cc: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
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 | 48 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       | 22 +++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5e715a9..2168318 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2448,6 +2448,15 @@ static long vfio_iommu_type1_unbind_gpasid(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 iommu_cache_invalidate_info *cache_inv_info =
+		(struct iommu_cache_invalidate_info *) dc->data;
+
+	return iommu_cache_invalidate(dc->domain, dev, cache_inv_info);
+}
+
 static long vfio_iommu_type1_ioctl(void *iommu_data,
 				   unsigned int cmd, unsigned long arg)
 {
@@ -2653,6 +2662,45 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 		default:
 			return -EINVAL;
 		}
+	} else if (cmd == VFIO_IOMMU_CACHE_INVALIDATE) {
+		struct vfio_iommu_type1_cache_invalidate cache_inv;
+		u32 version;
+		int info_size;
+		void *cache_info;
+		int ret;
+
+		minsz = offsetofend(struct vfio_iommu_type1_cache_invalidate,
+				    flags);
+
+		if (copy_from_user(&cache_inv, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (cache_inv.argsz < minsz || cache_inv.flags)
+			return -EINVAL;
+
+		/* Get the version of struct iommu_cache_invalidate_info */
+		if (copy_from_user(&version,
+			(void __user *) (arg + minsz), sizeof(version)))
+			return -EFAULT;
+
+		info_size = iommu_uapi_get_data_size(
+					IOMMU_UAPI_CACHE_INVAL, version);
+
+		cache_info = kzalloc(info_size, GFP_KERNEL);
+		if (!cache_info)
+			return -ENOMEM;
+
+		if (copy_from_user(cache_info,
+			(void __user *) (arg + minsz), info_size)) {
+			kfree(cache_info);
+			return -EFAULT;
+		}
+
+		mutex_lock(&iommu->lock);
+		ret = vfio_iommu_for_each_dev(iommu, vfio_cache_inv_fn,
+					    cache_info);
+		mutex_unlock(&iommu->lock);
+		return ret;
 	}
 
 	return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index b05fa97..b959d0a 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -920,6 +920,28 @@ struct vfio_iommu_type1_bind {
  */
 #define VFIO_IOMMU_BIND		_IO(VFIO_TYPE, VFIO_BASE + 25)
 
+/**
+ * VFIO_IOMMU_CACHE_INVALIDATE - _IOW(VFIO_TYPE, VFIO_BASE + 26,
+ *			struct vfio_iommu_type1_cache_invalidate)
+ *
+ * Propagate guest IOMMU cache invalidation to the host. The cache
+ * invalidation information is conveyed by @cache_info, the content
+ * format would be structures defined in uapi/linux/iommu.h. User
+ * should be aware of that the struct  iommu_cache_invalidate_info
+ * has a @version field, vfio needs to parse this field before getting
+ * data from userspace.
+ *
+ * Availability of this IOCTL is after VFIO_SET_IOMMU.
+ *
+ * returns: 0 on success, -errno on failure.
+ */
+struct vfio_iommu_type1_cache_invalidate {
+	__u32   argsz;
+	__u32   flags;
+	struct	iommu_cache_invalidate_info cache_info;
+};
+#define VFIO_IOMMU_CACHE_INVALIDATE      _IO(VFIO_TYPE, VFIO_BASE + 26)
+
 /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
 
 /*
-- 
2.7.4