vfio/migration: Add debugfs to live migration driver

There are multiple devices, software and operational steps involved
in the process of live migration. An error occurred on any node may
cause the live migration operation to fail.
This complex process makes it very difficult to locate and analyze
the cause when the function fails.

In order to quickly locate the cause of the problem when the
live migration fails, I added a set of debugfs to the vfio
live migration driver.

    +-------------------------------------------+
    |                                           |
    |                                           |
    |                  QEMU                     |
    |                                           |
    |                                           |
    +---+----------------------------+----------+
        |      ^                     |      ^
        |      |                     |      |
        |      |                     |      |
        v      |                     v      |
     +---------+--+               +---------+--+
     |src vfio_dev|               |dst vfio_dev|
     +--+---------+               +--+---------+
        |      ^                     |      ^
        |      |                     |      |
        v      |                     |      |
   +-----------+----+           +-----------+----+
   |src dev debugfs |           |dst dev debugfs |
   +----------------+           +----------------+

The entire debugfs directory will be based on the definition of
the CONFIG_DEBUG_FS macro. If this macro is not enabled, the
interfaces in vfio.h will be empty definitions, and the creation
and initialization of the debugfs directory will not be executed.

   vfio
    |
    +---<dev_name1>
    |    +---migration
    |        +--state
    |
    +---<dev_name2>
         +---migration
             +--state

debugfs will create a public root directory "vfio" file.
then create a dev_name() file for each live migration device.
First, create a unified state acquisition file of "migration"
in this device directory.
Then, create a public live migration state lookup file "state".

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20231106072225.28577-2-liulongfang@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Longfang Liu 2023-11-06 15:22:23 +08:00 committed by Alex Williamson
parent 33cc938e65
commit 2202844e44
7 changed files with 129 additions and 0 deletions

View file

@ -80,6 +80,16 @@ config VFIO_VIRQFD
select EVENTFD
default n
config VFIO_DEBUGFS
bool "Export VFIO internals in DebugFS"
depends on DEBUG_FS
help
Allows exposure of VFIO device internals. This option enables
the use of debugfs by VFIO drivers as required. The device can
cause the VFIO code create a top-level debug/vfio directory
during initialization, and then populate a subdirectory with
entries as required.
source "drivers/vfio/pci/Kconfig"
source "drivers/vfio/platform/Kconfig"
source "drivers/vfio/mdev/Kconfig"

View file

@ -7,6 +7,7 @@ vfio-$(CONFIG_VFIO_GROUP) += group.o
vfio-$(CONFIG_IOMMUFD) += iommufd.o
vfio-$(CONFIG_VFIO_CONTAINER) += container.o
vfio-$(CONFIG_VFIO_VIRQFD) += virqfd.o
vfio-$(CONFIG_VFIO_DEBUGFS) += debugfs.o
obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o

92
drivers/vfio/debugfs.c Normal file
View file

@ -0,0 +1,92 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2023, HiSilicon Ltd.
*/
#include <linux/device.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/vfio.h>
#include "vfio.h"
static struct dentry *vfio_debugfs_root;
static int vfio_device_state_read(struct seq_file *seq, void *data)
{
struct device *vf_dev = seq->private;
struct vfio_device *vdev = container_of(vf_dev,
struct vfio_device, device);
enum vfio_device_mig_state state;
int ret;
BUILD_BUG_ON(VFIO_DEVICE_STATE_NR !=
VFIO_DEVICE_STATE_PRE_COPY_P2P + 1);
ret = vdev->mig_ops->migration_get_state(vdev, &state);
if (ret)
return -EINVAL;
switch (state) {
case VFIO_DEVICE_STATE_ERROR:
seq_puts(seq, "ERROR\n");
break;
case VFIO_DEVICE_STATE_STOP:
seq_puts(seq, "STOP\n");
break;
case VFIO_DEVICE_STATE_RUNNING:
seq_puts(seq, "RUNNING\n");
break;
case VFIO_DEVICE_STATE_STOP_COPY:
seq_puts(seq, "STOP_COPY\n");
break;
case VFIO_DEVICE_STATE_RESUMING:
seq_puts(seq, "RESUMING\n");
break;
case VFIO_DEVICE_STATE_RUNNING_P2P:
seq_puts(seq, "RUNNING_P2P\n");
break;
case VFIO_DEVICE_STATE_PRE_COPY:
seq_puts(seq, "PRE_COPY\n");
break;
case VFIO_DEVICE_STATE_PRE_COPY_P2P:
seq_puts(seq, "PRE_COPY_P2P\n");
break;
default:
seq_puts(seq, "Invalid\n");
}
return 0;
}
void vfio_device_debugfs_init(struct vfio_device *vdev)
{
struct device *dev = &vdev->device;
vdev->debug_root = debugfs_create_dir(dev_name(vdev->dev),
vfio_debugfs_root);
if (vdev->mig_ops) {
struct dentry *vfio_dev_migration = NULL;
vfio_dev_migration = debugfs_create_dir("migration",
vdev->debug_root);
debugfs_create_devm_seqfile(dev, "state", vfio_dev_migration,
vfio_device_state_read);
}
}
void vfio_device_debugfs_exit(struct vfio_device *vdev)
{
debugfs_remove_recursive(vdev->debug_root);
}
void vfio_debugfs_create_root(void)
{
vfio_debugfs_root = debugfs_create_dir("vfio", NULL);
}
void vfio_debugfs_remove_root(void)
{
debugfs_remove_recursive(vfio_debugfs_root);
vfio_debugfs_root = NULL;
}

View file

@ -448,4 +448,18 @@ static inline void vfio_device_put_kvm(struct vfio_device *device)
}
#endif
#ifdef CONFIG_VFIO_DEBUGFS
void vfio_debugfs_create_root(void);
void vfio_debugfs_remove_root(void);
void vfio_device_debugfs_init(struct vfio_device *vdev);
void vfio_device_debugfs_exit(struct vfio_device *vdev);
#else
static inline void vfio_debugfs_create_root(void) { }
static inline void vfio_debugfs_remove_root(void) { }
static inline void vfio_device_debugfs_init(struct vfio_device *vdev) { }
static inline void vfio_device_debugfs_exit(struct vfio_device *vdev) { }
#endif /* CONFIG_VFIO_DEBUGFS */
#endif

View file

@ -311,6 +311,7 @@ static int __vfio_register_dev(struct vfio_device *device,
refcount_set(&device->refcount, 1);
vfio_device_group_register(device);
vfio_device_debugfs_init(device);
return 0;
err_out:
@ -378,6 +379,7 @@ void vfio_unregister_group_dev(struct vfio_device *device)
}
}
vfio_device_debugfs_exit(device);
/* Balances vfio_device_set_group in register path */
vfio_device_remove_group(device);
}
@ -1676,6 +1678,7 @@ static int __init vfio_init(void)
if (ret)
goto err_alloc_dev_chrdev;
vfio_debugfs_create_root();
pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
return 0;
@ -1691,6 +1694,7 @@ static int __init vfio_init(void)
static void __exit vfio_cleanup(void)
{
vfio_debugfs_remove_root();
ida_destroy(&vfio.device_ida);
vfio_cdev_cleanup();
class_destroy(vfio.device_class);

View file

@ -69,6 +69,13 @@ struct vfio_device {
u8 iommufd_attached:1;
#endif
u8 cdev_opened:1;
#ifdef CONFIG_DEBUG_FS
/*
* debug_root is a static property of the vfio_device
* which must be set prior to registering the vfio_device.
*/
struct dentry *debug_root;
#endif
};
/**

View file

@ -1219,6 +1219,7 @@ enum vfio_device_mig_state {
VFIO_DEVICE_STATE_RUNNING_P2P = 5,
VFIO_DEVICE_STATE_PRE_COPY = 6,
VFIO_DEVICE_STATE_PRE_COPY_P2P = 7,
VFIO_DEVICE_STATE_NR,
};
/**