Re: [PATCH V5 31/38] vfio/iommufd: cpr state

[Steven Sistare]

On 6/23/2025 6:45 AM, Duan, Zhenzhong wrote:

-----Original Message-----
From: Steve Sistare <steven.sist...@oracle.com>
Subject: [PATCH V5 31/38] vfio/iommufd: cpr state

VFIO iommufd devices will need access to ioas_id, devid, and hwpt_id in
new QEMU at realize time, so add them to CPR state.  Define CprVFIODevice
as the object which holds the state and is serialized to the vmstate file.
Define accessors to copy state between VFIODevice and CprVFIODevice.

Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
include/hw/vfio/vfio-cpr.h |  3 ++
hw/vfio/cpr-iommufd.c      | 96
+++++++++++++++++++++++++++++++++++++++++++++-
hw/vfio/iommufd.c          |  2 +
3 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/include/hw/vfio/vfio-cpr.h b/include/hw/vfio/vfio-cpr.h
index 619af07..f88e4ba 100644
--- a/include/hw/vfio/vfio-cpr.h
+++ b/include/hw/vfio/vfio-cpr.h
@@ -33,6 +33,8 @@ typedef struct VFIOContainerCPR {
typedef struct VFIODeviceCPR {
     Error *mdev_blocker;
     Error *id_blocker;
+    uint32_t hwpt_id;
+    uint32_t ioas_id;
} VFIODeviceCPR;

bool vfio_legacy_cpr_register_container(struct VFIOContainer *container,
@@ -54,6 +56,7 @@ bool vfio_iommufd_cpr_register_iommufd(struct
IOMMUFDBackend *be, Error **errp);
void vfio_iommufd_cpr_unregister_iommufd(struct IOMMUFDBackend *be);
void vfio_iommufd_cpr_register_device(struct VFIODevice *vbasedev);
void vfio_iommufd_cpr_unregister_device(struct VFIODevice *vbasedev);
+void vfio_cpr_load_device(struct VFIODevice *vbasedev);

int vfio_cpr_group_get_device_fd(int d, const char *name);

diff --git a/hw/vfio/cpr-iommufd.c b/hw/vfio/cpr-iommufd.c
index 3e78265..2eca8a6 100644
--- a/hw/vfio/cpr-iommufd.c
+++ b/hw/vfio/cpr-iommufd.c
@@ -7,6 +7,7 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/vfio/vfio-cpr.h"
+#include "hw/vfio/vfio-device.h"
#include "migration/blocker.h"
#include "migration/cpr.h"
#include "migration/migration.h"
@@ -14,7 +15,88 @@
#include "system/iommufd.h"
#include "vfio-iommufd.h"

-const VMStateDescription vmstate_cpr_vfio_devices;  /* TBD in a later patch */
+typedef struct CprVFIODevice {
+    char *name;
+    unsigned int namelen;
+    uint32_t ioas_id;
+    int devid;
+    uint32_t hwpt_id;
+    QLIST_ENTRY(CprVFIODevice) next;
+} CprVFIODevice;
+
+static const VMStateDescription vmstate_cpr_vfio_device = {
+    .name = "cpr vfio device",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(namelen, CprVFIODevice),
+        VMSTATE_VBUFFER_ALLOC_UINT32(name, CprVFIODevice, 0, NULL,
namelen),
+        VMSTATE_INT32(devid, CprVFIODevice),
+        VMSTATE_UINT32(ioas_id, CprVFIODevice),
+        VMSTATE_UINT32(hwpt_id, CprVFIODevice),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+const VMStateDescription vmstate_cpr_vfio_devices = {
+    .name = CPR_STATE "/vfio devices",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]){
+        VMSTATE_QLIST_V(vfio_devices, CprState, 1, vmstate_cpr_vfio_device,
+                        CprVFIODevice, next),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void vfio_cpr_save_device(VFIODevice *vbasedev)
+{
+    CprVFIODevice *elem = g_new0(CprVFIODevice, 1);
+
+    elem->name = g_strdup(vbasedev->name);
+    elem->namelen = strlen(vbasedev->name) + 1;
+    elem->ioas_id = vbasedev->cpr.ioas_id;
+    elem->devid = vbasedev->devid;
+    elem->hwpt_id = vbasedev->cpr.hwpt_id;
+    QLIST_INSERT_HEAD(&cpr_state.vfio_devices, elem, next);
+}
+
+static CprVFIODevice *find_device(const char *name)
+{
+    CprVFIODeviceList *head = &cpr_state.vfio_devices;
+    CprVFIODevice *elem;
+
+    QLIST_FOREACH(elem, head, next) {
+        if (!strcmp(elem->name, name)) {
+            return elem;
+        }
+    }
+    return NULL;
+}
+
+static void vfio_cpr_delete_device(const char *name)
+{
+    CprVFIODevice *elem = find_device(name);
+
+    if (elem) {
+        QLIST_REMOVE(elem, next);
+        g_free(elem->name);
+        g_free(elem);
+    }
+}
+
+static bool vfio_cpr_find_device(VFIODevice *vbasedev)

Better to rename as vfio_cpr_load_device

This is already called by a function named vfio_cpr_load_device.
The usage is the same as cpr_find_fd, so "find" is a consistent name.

+{
+    CprVFIODevice *elem = find_device(vbasedev->name);
+
+    if (elem) {
+        vbasedev->cpr.ioas_id = elem->ioas_id;
+        vbasedev->devid = elem->devid;
+        vbasedev->cpr.hwpt_id = elem->hwpt_id;
+        return true;
+    }
+    return false;
+}

static bool vfio_cpr_supported(IOMMUFDBackend *be, Error **errp)
{
@@ -79,8 +161,20 @@ void
vfio_iommufd_cpr_unregister_container(VFIOIOMMUFDContainer *container)

void vfio_iommufd_cpr_register_device(VFIODevice *vbasedev)
{
+    if (!cpr_is_incoming()) {
+        vfio_cpr_save_device(vbasedev);
+    }
}

void vfio_iommufd_cpr_unregister_device(VFIODevice *vbasedev)
{
+    vfio_cpr_delete_device(vbasedev->name);
+}
+
+void vfio_cpr_load_device(VFIODevice *vbasedev)
+{
+    if (cpr_is_incoming()) {
+        bool ret = vfio_cpr_find_device(vbasedev);
+        g_assert(ret);
+    }
}
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index ff291be..f0d57ea 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -515,6 +515,8 @@ static bool iommufd_cdev_attach(const char *name,
VFIODevice *vbasedev,
     const VFIOIOMMUClass *iommufd_vioc =

VFIO_IOMMU_CLASS(object_class_by_name(TYPE_VFIO_IOMMU_IOMMUFD));

+    vfio_cpr_load_device(vbasedev);

This can be open coded.

vfio_cpr_load_device grows in patch "preserve descriptors", so I would
rather keep it closed.

- Steve

+
     if (vbasedev->fd < 0) {
         devfd = iommufd_cdev_getfd(vbasedev->sysfsdev, errp);
         if (devfd < 0) {
--
1.8.3.1