[PATCH RFC 02/19] iommufd: Dirty tracking for io_pagetable

[Joao Martins <joao.m.martins@oracle.com>]

Add an io_pagetable kernel API to toggle dirty tracking:

* iopt_set_dirty_tracking(iopt, [domain], state)

It receives either NULL (which means all domains) or an
iommu_domain. The intended caller of this is via the hw_pagetable
object that is created on device attach, which passes an
iommu_domain. For now, the all-domains is left for vfio-compat.

The hw protection domain dirty control is favored over the IOVA-range
alternative. For the latter, it iterates over all IOVA areas and calls
iommu domain op to enable/disable for the range.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 drivers/iommu/iommufd/io_pagetable.c    | 71 +++++++++++++++++++++++++
 drivers/iommu/iommufd/iommufd_private.h |  3 ++
 2 files changed, 74 insertions(+)

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index f9f3b06946bf..f4609ef369e0 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -276,6 +276,77 @@ int iopt_map_user_pages(struct io_pagetable *iopt, unsigned long *iova,
 	return 0;
 }
 
+static int __set_dirty_tracking_range_locked(struct iommu_domain *domain,
+					     struct io_pagetable *iopt,
+					     bool enable)
+{
+	const struct iommu_domain_ops *ops = domain->ops;
+	struct iommu_iotlb_gather gather;
+	struct iopt_area *area;
+	int ret = -EOPNOTSUPP;
+	unsigned long iova;
+	size_t size;
+
+	iommu_iotlb_gather_init(&gather);
+
+	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX); area;
+	     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+		iova = iopt_area_iova(area);
+		size = iopt_area_last_iova(area) - iova;
+
+		if (ops->set_dirty_tracking_range) {
+			ret = ops->set_dirty_tracking_range(domain, iova,
+							    size, &gather,
+							    enable);
+			if (ret < 0)
+				break;
+		}
+	}
+
+	iommu_iotlb_sync(domain, &gather);
+
+	return ret;
+}
+
+static int iommu_set_dirty_tracking(struct iommu_domain *domain,
+				    struct io_pagetable *iopt, bool enable)
+{
+	const struct iommu_domain_ops *ops = domain->ops;
+	int ret = -EOPNOTSUPP;
+
+	if (ops->set_dirty_tracking)
+		ret = ops->set_dirty_tracking(domain, enable);
+	else if (ops->set_dirty_tracking_range)
+		ret = __set_dirty_tracking_range_locked(domain, iopt,
+							enable);
+
+	return ret;
+}
+
+int iopt_set_dirty_tracking(struct io_pagetable *iopt,
+			    struct iommu_domain *domain, bool enable)
+{
+	struct iommu_domain *dom;
+	unsigned long index;
+	int ret = -EOPNOTSUPP;
+
+	down_write(&iopt->iova_rwsem);
+	if (!domain) {
+		down_write(&iopt->domains_rwsem);
+		xa_for_each(&iopt->domains, index, dom) {
+			ret = iommu_set_dirty_tracking(dom, iopt, enable);
+			if (ret < 0)
+				break;
+		}
+		up_write(&iopt->domains_rwsem);
+	} else {
+		ret = iommu_set_dirty_tracking(domain, iopt, enable);
+	}
+
+	up_write(&iopt->iova_rwsem);
+	return ret;
+}
+
 struct iopt_pages *iopt_get_pages(struct io_pagetable *iopt, unsigned long iova,
 				  unsigned long *start_byte,
 				  unsigned long length)
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index f55654278ac4..d00ef3b785c5 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -49,6 +49,9 @@ int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
 		    unsigned long length);
 int iopt_unmap_all(struct io_pagetable *iopt);
 
+int iopt_set_dirty_tracking(struct io_pagetable *iopt,
+			    struct iommu_domain *domain, bool enable);
+
 int iopt_access_pages(struct io_pagetable *iopt, unsigned long iova,
 		      unsigned long npages, struct page **out_pages, bool write);
 void iopt_unaccess_pages(struct io_pagetable *iopt, unsigned long iova,
-- 
2.17.2

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