linux-kernel - [RFC PATCH v2 09/32] iommu: Implement IOMMU LU FLB preserve/unpreserve callbacks

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Message-ID: <20251202230303.1017519-10-skhawaja@google.com>
Date: Tue,  2 Dec 2025 23:02:39 +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 09/32] iommu: Implement IOMMU LU FLB
 preserve/unpreserve callbacks

Use KHO preserve memory alloc/free helper functions to allocate memory
for the IOMMU LU FLB. The serialization structs for device, domain and
iommu are allocated.

Signed-off-by: Samiullah Khawaja <skhawaja@...gle.com>
---
 drivers/iommu/liveupdate.c | 71 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/liveupdate.c b/drivers/iommu/liveupdate.c
index 93e5691a8c1f..21ce7be9b87e 100644
--- a/drivers/iommu/liveupdate.c
+++ b/drivers/iommu/liveupdate.c
@@ -10,15 +10,84 @@
 #include <linux/kexec_handover.h>
 #include <linux/liveupdate.h>
 #include <linux/iommu-lu.h>
+#include <linux/iommu.h>
 #include <linux/errno.h>
 
+static void iommu_liveupdate_free_objs(u64 next, bool incoming)
+{
+	struct iommu_objs_ser *objs;
+
+	while (next) {
+		objs = __va(next);
+		next = objs->next_objs;
+
+		if (!incoming)
+			kho_unpreserve_free(objs);
+		else
+			folio_put(virt_to_folio(objs));
+	}
+}
+
 static void iommu_liveupdate_flb_free(struct iommu_lu_flb_obj *obj)
 {
+	if (obj->iommu_domains)
+		iommu_liveupdate_free_objs(obj->ser->iommu_domains_phys, false);
+
+	if (obj->devices)
+		iommu_liveupdate_free_objs(obj->ser->devices_phys, false);
+
+	if (obj->iommus)
+		iommu_liveupdate_free_objs(obj->ser->iommus_phys, false);
+
+	kho_unpreserve_free(obj->ser);
 }
 
 static int iommu_liveupdate_flb_preserve(struct liveupdate_flb_op_args *argp)
 {
-	return -EOPNOTSUPP;
+	struct iommu_lu_flb_obj *obj;
+	struct iommu_lu_flb_ser *ser;
+	void *mem;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (!obj)
+		return -ENOMEM;
+
+	mutex_init(&obj->lock);
+	mem = kho_alloc_preserve(sizeof(*ser));
+	if (IS_ERR(mem))
+		goto err_free;
+
+	ser = mem;
+	obj->ser = ser;
+
+	mem = kho_alloc_preserve(PAGE_SIZE);
+	if (IS_ERR(mem))
+		goto err_free;
+
+	obj->iommu_domains = mem;
+	ser->iommu_domains_phys = virt_to_phys(obj->iommu_domains);
+
+	mem = kho_alloc_preserve(PAGE_SIZE);
+	if (IS_ERR(mem))
+		goto err_free;
+
+	obj->devices = mem;
+	ser->devices_phys = virt_to_phys(obj->devices);
+
+	mem = kho_alloc_preserve(PAGE_SIZE);
+	if (IS_ERR(mem))
+		goto err_free;
+
+	obj->iommus = mem;
+	ser->iommus_phys = virt_to_phys(obj->iommus);
+
+	argp->obj = obj;
+	argp->data = virt_to_phys(ser);
+	return 0;
+
+err_free:
+	iommu_liveupdate_flb_free(obj);
+	return PTR_ERR(mem);
 }
 
 static void iommu_liveupdate_flb_unpreserve(struct liveupdate_flb_op_args *argp)
-- 
2.52.0.158.g65b55ccf14-goog