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Message-Id: <20250728-luo-pci-v1-23-955b078dd653@kernel.org>
Date: Mon, 28 Jul 2025 01:24:53 -0700
From: chrisl@...nel.org
To: Bjorn Helgaas <bhelgaas@...gle.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>,
Len Brown <lenb@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, David Matlack <dmatlack@...gle.com>,
Pasha Tatashin <tatashin@...gle.com>, Jason Miu <jasonmiu@...gle.com>,
Vipin Sharma <vipinsh@...gle.com>, Saeed Mahameed <saeedm@...dia.com>,
Adithya Jayachandran <ajayachandra@...dia.com>,
Parav Pandit <parav@...dia.com>, William Tu <witu@...dia.com>,
Mike Rapoport <rppt@...nel.org>, Chris Li <chrisl@...nel.org>,
Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>
Subject: [PATCH RFC 23/25] PCI/LUO: Check the PCI bus state after
restoration
From: Jason Miu <jasonmiu@...gle.com>
After the LUO reboot, check if the bus topology assoicated with the
current PCI device is matching with the bus states saved in LUO. We like
to verify:
- The domain and bus numbers.
- The parent bus domain and number.
- The bus type, which can be PCI-PCI bridge, host bridge, or virtual bus.
- PCI bridge resource of host bridge, as different from PCI-PCI bridge
which the resource is restorated from the PCI bridge device, we check
if the host bridge resource is changed from the last boot.
Tested:
- QEMU VM liveupdate boot test with pci-lu-stub
Signed-off-by: Chris Li <chrisl@...nel.org>
---
drivers/pci/liveupdate.c | 123 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 110 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/liveupdate.c b/drivers/pci/liveupdate.c
index be22af7a2db3a9bb06d8e100603a59f11b7fa5f8..739de5f655dba04024c9cf8db2bf6ea5e136cf5f 100644
--- a/drivers/pci/liveupdate.c
+++ b/drivers/pci/liveupdate.c
@@ -43,6 +43,45 @@ struct pci_ser {
/* struct pci_bus_ser buses[] */
};
+static struct pci_bus_ser *get_saved_pci_bus_state(struct pci_ser *state,
+ u16 domain, u8 number)
+{
+ int i;
+ struct pci_bus_ser *bus_state =
+ (struct pci_bus_ser *)(state->devs + state->dev_count);
+
+ for (i = 0; i < state->bus_count; i++, bus_state++) {
+ if (bus_state->domain == domain &&
+ bus_state->number == number)
+ return bus_state;
+ }
+
+ return NULL;
+}
+
+static enum pci_bus_ser_bridge_type get_bus_ser_bridge_type(struct pci_bus *bus)
+{
+ /* This bus is a virtual bus if no physical bridge is being referred. */
+ if (!bus->bridge)
+ return PCI_BUS_SER_NULL_BRIDGE;
+
+ return pci_is_root_bus(bus) ?
+ PCI_BUS_SER_PCI_HOST_BRIDGE : PCI_BUS_SER_PCI_BRIDGE;
+}
+
+static char *bus_ser_bridge_type_to_string(enum pci_bus_ser_bridge_type bt)
+{
+ switch (bt) {
+ case PCI_BUS_SER_NULL_BRIDGE:
+ return "PCI_BUS_SER_NULL_BRIDGE";
+ case PCI_BUS_SER_PCI_BRIDGE:
+ return "PCI_BUS_SER_PCI_BRIDGE";
+ case PCI_BUS_SER_PCI_HOST_BRIDGE:
+ return "PCI_BUS_SER_PCI_HOST_BRIDGE";
+ }
+ return "PCI_BUS_SER_INVALID";
+}
+
static void stack_push_buses(struct list_head *stack, struct list_head *buses)
{
struct pci_bus *bus;
@@ -183,6 +222,71 @@ static void save_device_resource(struct pci_resource_ser *dest,
dest->desc = src->desc;
}
+static void check_saved_bus_state(struct pci_dev *dev, struct pci_ser *pci_state)
+{
+ int i;
+ const struct resource *res;
+ const struct pci_resource_ser *saved_res;
+ const struct pci_bus_ser *bus_state =
+ get_saved_pci_bus_state(pci_state,
+ pci_domain_nr(dev->bus),
+ dev->bus->number);
+ struct pci_bus *bus = dev->bus;
+
+ if (!bus_state) {
+ panic("The bus of PCI device %s was not preserved by Liveupdate",
+ pci_name(dev));
+ }
+
+ if (get_bus_ser_bridge_type(bus) != bus_state->bridge_type) {
+ panic("The bus (%04x:%02x) bridge type (%s) of PCI device (%s) is changed. "
+ "Liveupdate preserved %s",
+ pci_domain_nr(bus), bus->number,
+ bus_ser_bridge_type_to_string(get_bus_ser_bridge_type(bus)),
+ pci_name(dev),
+ bus_ser_bridge_type_to_string(bus_state->bridge_type));
+ }
+
+ if (bus->parent) {
+ if (pci_domain_nr(bus->parent) != bus_state->parent_domain ||
+ bus->parent->number != bus_state->parent_number) {
+ panic("The parent bus (%04x:%02x) of PCI device (%s) is changed. "
+ "Liveupdate preserved %04x:%02x",
+ pci_domain_nr(bus->parent), bus->parent->number,
+ pci_name(dev),
+ bus_state->parent_domain, bus_state->parent_number);
+ }
+
+ /* Checkings of PCI-PCI bridge and Virtual bus ends. */
+ return;
+ }
+
+ /* This is a host bridge device */
+ for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) {
+
+ res = bus->resource[i];
+ if (res == NULL ||
+ res->name == NULL ||
+ strlen(res->name) == 0)
+ continue;
+
+ /* check its PCI bridge resource */
+ saved_res = &bus_state->resource[i];
+ if (res->start != saved_res->start ||
+ res->end != saved_res->end ||
+ res->flags != saved_res->flags ||
+ res->desc != saved_res->desc ||
+ strncmp(res->name, saved_res->name, sizeof(saved_res->name)) != 0) {
+ panic("Host bridge resource %pr is changed. "
+ "Liveupdate preserved "
+ "[mem 0x%016llx-0x%016llx flags 0x%016llx desc 0x%016llx name %s]",
+ res,
+ saved_res->start, saved_res->end,
+ saved_res->flags, saved_res->desc, saved_res->name);
+ }
+ }
+}
+
static int pci_save_device_state(struct device *dev, struct pci_dev_ser *s)
{
struct pci_dev *pdev = to_pci_dev(dev);
@@ -238,22 +342,13 @@ static void pci_save_bus_state(struct pci_bus *bus, struct pci_bus_ser *s)
s->domain = pci_domain_nr(bus);
s->number = bus->number;
+ s->bridge_type = get_bus_ser_bridge_type(bus);
+
if (bus->parent) {
s->parent_domain = pci_domain_nr(bus->parent);
s->parent_number = bus->parent->number;
}
- /* This bus is a virtual bus if no physical bridge is being referred. */
- if (!bus->bridge) {
- s->bridge_type = PCI_BUS_SER_NULL_BRIDGE;
- return;
- }
-
- if (!pci_is_root_bus(bus)) {
- s->bridge_type = PCI_BUS_SER_PCI_BRIDGE;
- return;
- }
-
/* This bridge is a PCI host bridge. Saves its resource. */
for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) {
/* This resource region is not claimed, skip. */
@@ -264,7 +359,6 @@ static void pci_save_bus_state(struct pci_bus *bus, struct pci_bus_ser *s)
save_device_resource(s->resource + i, bus->resource[i]);
}
- s->bridge_type = PCI_BUS_SER_PCI_HOST_BRIDGE;
}
static int pci_call_prepare(struct pci_ser *pci_state,
@@ -531,8 +625,11 @@ void pci_liveupdate_restore(struct pci_dev *dev)
s = pci_state->devs;
end = s + pci_state->dev_count;
for (; s < end; s++)
- if (s->path == path)
+ if (s->path == path) {
+ /* If the bus state checking fails, kernel panics */
+ check_saved_bus_state(dev, pci_state);
return pci_dev_do_restore(dev, s);
+ }
}
int pci_liveupdate_get_driver_data(struct pci_dev *pdev, u64 *data)
--
2.50.1.487.gc89ff58d15-goog
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