linux-kernel - [RFC PATCH v2 22/32] iommu: Implement IOMMU FLB retrieve and finish ops

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Message-ID: <20251202230303.1017519-23-skhawaja@google.com>
Date: Tue,  2 Dec 2025 23:02:52 +0000
From: Samiullah Khawaja <skhawaja@...gle.com>
To: David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>, 
	Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>, 
	Pasha Tatashin <pasha.tatashin@...een.com>, Jason Gunthorpe <jgg@...pe.ca>, iommu@...ts.linux.dev
Cc: Samiullah Khawaja <skhawaja@...gle.com>, Robin Murphy <robin.murphy@....com>, 
	Pratyush Yadav <pratyush@...nel.org>, Kevin Tian <kevin.tian@...el.com>, 
	Alex Williamson <alex@...zbot.org>, linux-kernel@...r.kernel.org, 
	Saeed Mahameed <saeedm@...dia.com>, Adithya Jayachandran <ajayachandra@...dia.com>, 
	Parav Pandit <parav@...dia.com>, Leon Romanovsky <leonro@...dia.com>, William Tu <witu@...dia.com>, 
	Vipin Sharma <vipinsh@...gle.com>, dmatlack@...gle.com, YiFei Zhu <zhuyifei@...gle.com>, 
	Chris Li <chrisl@...nel.org>, praan@...gle.com
Subject: [RFC PATCH v2 22/32] iommu: Implement IOMMU FLB retrieve and finish ops

Add implementation of the IOMMU LU FLB retrieve and finish ops. During
retrieve walk through the preserved objs nodes and restore each folio.
Also recreate the FLB obj.

Signed-off-by: Samiullah Khawaja <skhawaja@...gle.com>
---
 drivers/iommu/liveupdate.c | 48 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/liveupdate.c b/drivers/iommu/liveupdate.c
index 5780761a7024..0dfa03673178 100644
--- a/drivers/iommu/liveupdate.c
+++ b/drivers/iommu/liveupdate.c
@@ -14,6 +14,17 @@
 #include <linux/pci.h>
 #include <linux/errno.h>
 
+static void iommu_liveupdate_restore_objs(u64 next)
+{
+	struct iommu_objs_ser *objs;
+
+	while (next) {
+		BUG_ON(!kho_restore_folio(next));
+		objs = __va(next);
+		next = objs->next_objs;
+	}
+}
+
 static void iommu_liveupdate_free_objs(u64 next, bool incoming)
 {
 	struct iommu_objs_ser *objs;
@@ -98,11 +109,46 @@ static void iommu_liveupdate_flb_unpreserve(struct liveupdate_flb_op_args *argp)
 
 static void iommu_liveupdate_flb_finish(struct liveupdate_flb_op_args *argp)
 {
+	struct iommu_lu_flb_obj *obj = argp->obj;
+
+	if (obj->iommu_domains)
+		iommu_liveupdate_free_objs(obj->ser->iommu_domains_phys, true);
+
+	if (obj->devices)
+		iommu_liveupdate_free_objs(obj->ser->devices_phys, true);
+
+	if (obj->iommus)
+		iommu_liveupdate_free_objs(obj->ser->iommus_phys, true);
+
+	folio_put(virt_to_folio(obj->ser));
 }
 
 static int iommu_liveupdate_flb_retrieve(struct liveupdate_flb_op_args *argp)
 {
-	return -EOPNOTSUPP;
+	struct iommu_lu_flb_obj *obj;
+	struct iommu_lu_flb_ser *ser;
+
+	obj = kzalloc(sizeof(*obj), GFP_ATOMIC);
+	if (!obj)
+		return -ENOMEM;
+
+	mutex_init(&obj->lock);
+	BUG_ON(!kho_restore_folio(argp->data));
+	ser = phys_to_virt(argp->data);
+	obj->ser = ser;
+
+	iommu_liveupdate_restore_objs(ser->iommu_domains_phys);
+	obj->iommu_domains = phys_to_virt(ser->iommu_domains_phys);
+
+	iommu_liveupdate_restore_objs(ser->devices_phys);
+	obj->devices = phys_to_virt(ser->devices_phys);
+
+	iommu_liveupdate_restore_objs(ser->iommus_phys);
+	obj->iommus = phys_to_virt(ser->iommus_phys);
+
+	argp->obj = obj;
+
+	return 0;
 }
 
 static struct liveupdate_flb_ops iommu_flb_ops = {
-- 
2.52.0.158.g65b55ccf14-goog