[RFC PATCH 05/13] iommufd: Serialise persisted iommufds and ioas

James Gowans
2024-09-16T11:33:01Z

Now actually implementing the serialise callback for iommufd.
On KHO activate, iterate through all persisted domains and write their
metadata to the device tree format. For now just a few fields are
serialised to demonstrate the concept. To actually make this useful a
lot more field and related objects will need to be serialised too.
---
drivers/iommu/iommufd/iommufd_private.h | 2 +
drivers/iommu/iommufd/main.c | 2 +-
drivers/iommu/iommufd/serialise.c | 81 ++++++++++++++++++++++++-
3 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index a26728646a22..ad8d180269bd 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -18,6 +18,8 @@ struct iommu_group;
struct iommu_option;
struct iommufd_device;

+extern struct xarray persistent_iommufds;
+
struct iommufd_ctx {
struct file *file;
struct xarray objects;
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index fa4f0fe336ad..21a7e1ad40d1 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -30,7 +30,7 @@ struct iommufd_object_ops {
static const struct iommufd_object_ops iommufd_object_ops[];
static struct miscdevice vfio_misc_dev;

-static DEFINE_XARRAY_ALLOC(persistent_iommufds);
+DEFINE_XARRAY_ALLOC(persistent_iommufds);

struct iommufd_object *_iommufd_object_alloc(struct iommufd_ctx *ictx,
size_t size,
diff --git a/drivers/iommu/iommufd/serialise.c b/drivers/iommu/iommufd/serialise.c
index 6e8bcc384771..6b4c306dce40 100644
--- a/drivers/iommu/iommufd/serialise.c
+++ b/drivers/iommu/iommufd/serialise.c
@@ -1,19 +1,94 @@
// SPDX-License-Identifier: GPL-2.0-only

#include <linux/kexec.h>
+#include <linux/libfdt.h>
#include "iommufd_private.h"
+#include "io_pagetable.h"
+
+/**
+ * Serialised format:
+ * /iommufd
+ * compatible = "iommufd-v0",
+ * iommufds = [
+ * persistent_id = {
+ * account_mode = u8
+ * ioases = [
+ * {
+ * areas = [
+ * ]
+ * }
+ * ]
+ * }
+ * ]
+ */
+static int serialise_iommufd(void *fdt, struct iommufd_ctx *ictx)
+{
+ int err = 0;
+ char name[24];
+ struct iommufd_object *obj;
+ unsigned long obj_idx;
+
+ snprintf(name, sizeof(name), "%lu", ictx->persistent_id);
+ err |= fdt_begin_node(fdt, name);
+ err |= fdt_begin_node(fdt, "ioases");
+ xa_for_each(&ictx->objects, obj_idx, obj) {
+ struct iommufd_ioas *ioas;
+ struct iopt_area *area;
+ int area_idx = 0;
+
+ if (obj->type != IOMMUFD_OBJ_IOAS)
+ continue;
+
+ ioas = (struct iommufd_ioas *) obj;
+ snprintf(name, sizeof(name), "%lu", obj_idx);
+ err |= fdt_begin_node(fdt, name);
+
+ for (area = iopt_area_iter_first(&ioas->iopt, 0, ULONG_MAX); area;
+ area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+ unsigned long iova_start, iova_len;
+
+ snprintf(name, sizeof(name), "%i", area_idx);
+ err |= fdt_begin_node(fdt, name);
+ iova_start = iopt_area_iova(area);
+ iova_len = iopt_area_length(area);
+ err |= fdt_property(fdt, "iova-start",
+ &iova_start, sizeof(iova_start));
+ err |= fdt_property(fdt, "iova-len",
+ &iova_len, sizeof(iova_len));
+ err |= fdt_property(fdt, "iommu-prot",
+ &area->iommu_prot, sizeof(area->iommu_prot));
+ err |= fdt_end_node(fdt); /* area_idx */
+ ++area_idx;
+ }
+ err |= fdt_end_node(fdt); /* ioas obj_idx */
+ }
+ err |= fdt_end_node(fdt); /* ioases*/
+ err |= fdt_end_node(fdt); /* ictx->persistent_id */
+ return 0;
+}

int iommufd_serialise_kho(struct notifier_block *self, unsigned long cmd,
void *fdt)
{
- pr_info("would serialise here\n");
+ static const char compatible[] = "iommufd-v0";
+ struct iommufd_ctx *ictx;
+ unsigned long xa_idx;
+ int err = 0;
+
switch (cmd) {
case KEXEC_KHO_ABORT:
/* Would do serialise rollback here. */
return NOTIFY_DONE;
case KEXEC_KHO_DUMP:
- /* Would do serialise here. */
- return NOTIFY_DONE;
+ err |= fdt_begin_node(fdt, "iommufd");
+ fdt_property(fdt, "compatible", compatible, sizeof(compatible));
+ err |= fdt_begin_node(fdt, "iommufds");
+ xa_for_each(&persistent_iommufds, xa_idx, ictx) {
+ err |= serialise_iommufd(fdt, ictx);
+ }
+ err |= fdt_end_node(fdt); /* iommufds */
+ err |= fdt_end_node(fdt); /* iommufd */
+ return err? NOTIFY_BAD : NOTIFY_DONE;
default:
return NOTIFY_BAD;
}
--
2.34.1