[RFC PATCH v2 23/32] iommu: Add an API get the preserved state of an IOMMU

[Samiullah Khawaja]

After liveupdate kexec during boot, the state of the preserved IOMMU
needs to be restored. Since the state needs to be restored by the IOMMU
drivers during initialization/registration with the IOMMU core, add an
API that can be used by the IOMMU drivers to fetch the preserved state.

Signed-off-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
---
 drivers/iommu/liveupdate.c | 29 +++++++++++++++++++++++++++++
 include/linux/iommu-lu.h   |  1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/iommu/liveupdate.c b/drivers/iommu/liveupdate.c
index 0dfa03673178..e7ecf2e9aa4e 100644
--- a/drivers/iommu/liveupdate.c
+++ b/drivers/iommu/liveupdate.c
@@ -175,6 +175,35 @@ int iommu_liveupdate_unregister_flb(struct liveupdate_file_handler *handler)
 }
 EXPORT_SYMBOL(iommu_liveupdate_unregister_flb);
 
+struct iommu_ser *iommu_get_preserved_data(u64 token, enum iommu_lu_type type)
+{
+	struct iommu_lu_flb_obj *obj;
+	struct iommus_ser *iommus;
+	int ret, i, idx;
+
+	ret = liveupdate_flb_get_incoming(&iommu_flb, (void **)&obj);
+	if (ret)
+		return NULL;
+
+	iommus = __va(obj->ser->iommus_phys);
+	for (i = 0, idx = 0; i < obj->ser->nr_iommus; ++i, ++idx) {
+		if (idx >= MAX_IOMMU_SERS) {
+			iommus = __va(iommus->objs.next_objs);
+			idx = 0;
+		}
+
+		if (iommus->iommus[idx].obj.deleted)
+			continue;
+
+		if (iommus->iommus[idx].token == token &&
+		    iommus->iommus[idx].type == type)
+			return &iommus->iommus[idx];
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(iommu_get_preserved_data);
+
 static int reserve_obj_ser(struct iommu_objs_ser **objs_ptr, u64 max_objs)
 {
 	struct iommu_objs_ser *next_objs, *objs = *objs_ptr;
diff --git a/include/linux/iommu-lu.h b/include/linux/iommu-lu.h
index 08a659de8553..ffce7043e997 100644
--- a/include/linux/iommu-lu.h
+++ b/include/linux/iommu-lu.h
@@ -78,6 +78,7 @@ static inline void *iommu_domain_restored_state(struct iommu_domain *domain)
 }
 #endif
 
+struct iommu_ser *iommu_get_preserved_data(u64 token, enum iommu_lu_type type);
 int iommu_domain_preserve(struct iommu_domain *domain, struct iommu_domain_ser **ser);
 int iommu_domain_unpreserve(struct iommu_domain *domain);
 int iommu_preserve_device(struct iommu_domain *domain, struct device *dev);
-- 
2.52.0.158.g65b55ccf14-goog