>-----Original Message-----
>From: Steve Sistare <steven.sist...@oracle.com>
>Subject: [PATCH V5 30/38] migration: vfio cpr state hook
>
>Define a list of vfio devices in CPR state, in a subsection so that
>older QEMU can be live updated to this version. However, new QEMU
>will not be live updateable to old QEMU. This is acceptable because
>CPR is not yet commonly used, and updates to older versions are unusual.
I'm not familiar with migration, may I ask how subsection help blocking
migration
from new to old QEMU?
>
>The contents of each device object will be defined by the vfio subsystem
>in a subsequent patch.
>
>Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
>---
> include/hw/vfio/vfio-cpr.h | 1 +
> include/migration/cpr.h | 12 ++++++++++++
> hw/vfio/cpr-iommufd.c | 2 ++
> hw/vfio/iommufd-stubs.c | 18 ++++++++++++++++++
> migration/cpr.c | 14 +++++---------
> hw/vfio/meson.build | 1 +
> 6 files changed, 39 insertions(+), 9 deletions(-)
> create mode 100644 hw/vfio/iommufd-stubs.c
>
>diff --git a/include/hw/vfio/vfio-cpr.h b/include/hw/vfio/vfio-cpr.h
>index b9b77ae..619af07 100644
>--- a/include/hw/vfio/vfio-cpr.h
>+++ b/include/hw/vfio/vfio-cpr.h
>@@ -74,5 +74,6 @@ void vfio_cpr_delete_vector_fd(struct VFIOPCIDevice *vdev,
>const char *name,
> int nr);
>
> extern const VMStateDescription vfio_cpr_pci_vmstate;
>+extern const VMStateDescription vmstate_cpr_vfio_devices;
>
> #endif /* HW_VFIO_VFIO_CPR_H */
>diff --git a/include/migration/cpr.h b/include/migration/cpr.h
>index 7fd8065..8fd8bfe 100644
>--- a/include/migration/cpr.h
>+++ b/include/migration/cpr.h
>@@ -9,11 +9,23 @@
> #define MIGRATION_CPR_H
>
> #include "qapi/qapi-types-migration.h"
>+#include "qemu/queue.h"
>
> #define MIG_MODE_NONE -1
>
> #define QEMU_CPR_FILE_MAGIC 0x51435052
> #define QEMU_CPR_FILE_VERSION 0x00000001
>+#define CPR_STATE "CprState"
>+
>+typedef QLIST_HEAD(CprFdList, CprFd) CprFdList;
>+typedef QLIST_HEAD(CprVFIODeviceList, CprVFIODevice) CprVFIODeviceList;
>+
>+typedef struct CprState {
>+ CprFdList fds;
>+ CprVFIODeviceList vfio_devices;
>+} CprState;
>+
>+extern CprState cpr_state;
>
> void cpr_save_fd(const char *name, int id, int fd);
> void cpr_delete_fd(const char *name, int id);
>diff --git a/hw/vfio/cpr-iommufd.c b/hw/vfio/cpr-iommufd.c
>index 60bd7e8..3e78265 100644
>--- a/hw/vfio/cpr-iommufd.c
>+++ b/hw/vfio/cpr-iommufd.c
>@@ -14,6 +14,8 @@
> #include "system/iommufd.h"
> #include "vfio-iommufd.h"
>
>+const VMStateDescription vmstate_cpr_vfio_devices; /* TBD in a later patch */
>+
> static bool vfio_cpr_supported(IOMMUFDBackend *be, Error **errp)
> {
> if (!iommufd_change_process_capable(be)) {
>diff --git a/hw/vfio/iommufd-stubs.c b/hw/vfio/iommufd-stubs.c
>new file mode 100644
>index 0000000..0be5276
>--- /dev/null
>+++ b/hw/vfio/iommufd-stubs.c
>@@ -0,0 +1,18 @@
>+/*
>+ * Copyright (c) 2025 Oracle and/or its affiliates.
>+ *
>+ * SPDX-License-Identifier: GPL-2.0-or-later
>+ */
>+
>+#include "qemu/osdep.h"
>+#include "migration/cpr.h"
>+#include "migration/vmstate.h"
>+
>+const VMStateDescription vmstate_cpr_vfio_devices = {
>+ .name = CPR_STATE "/vfio devices",
>+ .version_id = 1,
>+ .minimum_version_id = 1,
Is there difference if version_id=minimum_version_id=0?
Thanks
Zhenzhong
>+ .fields = (const VMStateField[]){
>+ VMSTATE_END_OF_LIST()
>+ }
>+};
>diff --git a/migration/cpr.c b/migration/cpr.c
>index 4574608..47898ab 100644
>--- a/migration/cpr.c
>+++ b/migration/cpr.c
>@@ -22,13 +22,7 @@
>
>/*****************************************************************
>********/
> /* cpr state container for all information to be saved. */
>
>-typedef QLIST_HEAD(CprFdList, CprFd) CprFdList;
>-
>-typedef struct CprState {
>- CprFdList fds;
>-} CprState;
>-
>-static CprState cpr_state;
>+CprState cpr_state;
>
>
>/*****************************************************************
>***********/
>
>@@ -129,8 +123,6 @@ int cpr_open_fd(const char *path, int flags, const char
>*name, int id,
> }
>
>
>/*****************************************************************
>********/
>-#define CPR_STATE "CprState"
>-
> static const VMStateDescription vmstate_cpr_state = {
> .name = CPR_STATE,
> .version_id = 1,
>@@ -138,6 +130,10 @@ static const VMStateDescription vmstate_cpr_state = {
> .fields = (VMStateField[]) {
> VMSTATE_QLIST_V(fds, CprState, 1, vmstate_cpr_fd, CprFd, next),
> VMSTATE_END_OF_LIST()
>+ },
>+ .subsections = (const VMStateDescription * const []) {
>+ &vmstate_cpr_vfio_devices,
>+ NULL
> }
> };
>
>/*****************************************************************
>********/
>diff --git a/hw/vfio/meson.build b/hw/vfio/meson.build
>index 56373e3..b9420cf 100644
>--- a/hw/vfio/meson.build
>+++ b/hw/vfio/meson.build
>@@ -33,6 +33,7 @@ system_ss.add(when: ['CONFIG_VFIO',
>'CONFIG_IOMMUFD'], if_true: files(
> 'iommufd.c',
> 'cpr-iommufd.c',
> ))
>+system_ss.add(when: 'CONFIG_IOMMUFD', if_false: files('iommufd-stubs.c'))
> system_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
> 'display.c',
> ))
>--
>1.8.3.1
