[PATCH v3 10/14] vfio/type1: Allow invalidating first-level/stage IOMMU cache

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

This patch provides an interface allowing the userspace to invalidate
IOMMU cache for first-level page table. It is required when the first
level IOMMU page table is not managed by the host kernel in the nested
translation setup.

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@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
v1 -> v2:
*) rename from "vfio/type1: Flush stage-1 IOMMU cache for nesting type"
*) rename vfio_cache_inv_fn() to vfio_dev_cache_invalidate_fn()
*) vfio_dev_cache_inv_fn() always successful
*) remove VFIO_IOMMU_CACHE_INVALIDATE, and reuse VFIO_IOMMU_NESTING_OP
---
 drivers/vfio/vfio_iommu_type1.c | 52 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  3 +++
 2 files changed, 55 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5926533..4c21300 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -3080,6 +3080,53 @@ static long vfio_iommu_handle_pgtbl_op(struct vfio_iommu *iommu,
 	return ret;
 }
 
+static int vfio_dev_cache_invalidate_fn(struct device *dev, void *data)
+{
+	struct domain_capsule *dc = (struct domain_capsule *)data;
+	unsigned long arg = *(unsigned long *) dc->data;
+
+	iommu_cache_invalidate(dc->domain, dev, (void __user *) arg);
+	return 0;
+}
+
+static long vfio_iommu_invalidate_cache(struct vfio_iommu *iommu,
+					unsigned long arg)
+{
+	struct domain_capsule dc = { .data = &arg };
+	struct vfio_group *group;
+	struct vfio_domain *domain;
+	int ret = 0;
+	struct iommu_nesting_info *info;
+
+	mutex_lock(&iommu->lock);
+	/*
+	 * Cache invalidation is required for any nesting IOMMU,
+	 * so no need to check system-wide PASID support.
+	 */
+	info = iommu->nesting_info;
+	if (!info || !(info->features & IOMMU_NESTING_FEAT_CACHE_INVLD)) {
+		ret = -ENOTSUPP;
+		goto out_unlock;
+	}
+
+	group = vfio_find_nesting_group(iommu);
+	if (!group) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	domain = list_first_entry(&iommu->domain_list,
+				      struct vfio_domain, next);
+	dc.group = group;
+	dc.domain = domain->domain;
+	iommu_group_for_each_dev(group->iommu_group, &dc,
+				 vfio_dev_cache_invalidate_fn);
+
+out_unlock:
+	mutex_unlock(&iommu->lock);
+	return ret;
+}
+
 static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
 					unsigned long arg)
 {
@@ -3102,6 +3149,11 @@ static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
 	case VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL:
 		ret = vfio_iommu_handle_pgtbl_op(iommu, false, arg + minsz);
 		break;
+	case VFIO_IOMMU_NESTING_OP_CACHE_INVLD:
+	{
+		ret = vfio_iommu_invalidate_cache(iommu, arg + minsz);
+		break;
+	}
 	default:
 		ret = -EINVAL;
 	}
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 2c9def8..7f8678e 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -1213,6 +1213,8 @@ struct vfio_iommu_type1_pasid_request {
  * +-----------------+-----------------------------------------------+
  * | UNBIND_PGTBL    |      struct iommu_gpasid_bind_data            |
  * +-----------------+-----------------------------------------------+
+ * | CACHE_INVLD     |      struct iommu_cache_invalidate_info       |
+ * +-----------------+-----------------------------------------------+
  *
  * returns: 0 on success, -errno on failure.
  */
@@ -1225,6 +1227,7 @@ struct vfio_iommu_type1_nesting_op {
 
 #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL	(0)
 #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL	(1)
+#define VFIO_IOMMU_NESTING_OP_CACHE_INVLD	(2)
 
 #define VFIO_IOMMU_NESTING_OP		_IO(VFIO_TYPE, VFIO_BASE + 19)
 
-- 
2.7.4