[PATCH v15 0/2] add debugfs to migration driver

[PATCH v15 0/2] add debugfs to migration driver

[liulongfang]

Add a debugfs function to the migration driver in VFIO to provide
a step-by-step debugfs information for the migration driver.

Changes v14 -> v15
	Update the output status value of live migration.

Changes v13 -> v14
	Split the patchset and keep the vfio debugfs frame.

Changes v12 -> v13
	Solve the problem of open and close competition to debugfs.

Changes v11 -> v12
	Update loading conditions of vfio debugfs.

Changes v10 -> v11
	Delete the device restore function in debugfs.

Changes v9 -> v10
	Update the debugfs file of the live migration driver.

Changes v8 -> v9
	Update the debugfs directory structure of vfio.

Changes v7 -> v8
	Add support for platform devices.

Changes v6 -> v7
	Fix some code style issues.

Changes v5 -> v6
	Control the creation of debugfs through the CONFIG_DEBUG_FS.

Changes v4 -> v5
	Remove the newly added vfio_migration_ops and use seq_printf
	to optimize the implementation of debugfs.

Changes v3 -> v4
	Change the migration_debug_operate interface to debug_root file.

Changes v2 -> v3
	Extend the debugfs function from hisilicon device to vfio.

Changes v1 -> v2
	Change the registration method of root_debugfs to register
	with module initialization.

Longfang Liu (2):
  vfio/migration: Add debugfs to live migration driver
  Documentation: add debugfs description for vfio

 Documentation/ABI/testing/debugfs-vfio | 25 ++++++++
 MAINTAINERS                            |  1 +
 drivers/vfio/Makefile                  |  1 +
 drivers/vfio/vfio.h                    | 14 +++++
 drivers/vfio/vfio_debugfs.c            | 80 ++++++++++++++++++++++++++
 drivers/vfio/vfio_main.c               |  5 +-
 include/linux/vfio.h                   |  7 +++
 7 files changed, 132 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/debugfs-vfio
 create mode 100644 drivers/vfio/vfio_debugfs.c

-- 
2.24.0

[PATCH v15 1/2] vfio/migration: Add debugfs to live migration driver

[liulongfang]

From: Longfang Liu <liulongfang@huawei.com>

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"
Finally, create a directory file based on the device type,
and then create the device's own debugging files under
this directory file.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
---
 drivers/vfio/Makefile       |  1 +
 drivers/vfio/vfio.h         | 14 +++++++
 drivers/vfio/vfio_debugfs.c | 80 +++++++++++++++++++++++++++++++++++++
 drivers/vfio/vfio_main.c    |  5 ++-
 include/linux/vfio.h        |  7 ++++
 5 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 drivers/vfio/vfio_debugfs.c

diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
index c82ea032d352..7934ac829989 100644
--- a/drivers/vfio/Makefile
+++ b/drivers/vfio/Makefile
@@ -8,6 +8,7 @@ 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_DEBUG_FS) += vfio_debugfs.o
 
 obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
 obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 307e3f29b527..09b00757d0bb 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -448,4 +448,18 @@ static inline void vfio_device_put_kvm(struct vfio_device *device)
 }
 #endif
 
+#ifdef CONFIG_DEBUG_FS
+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_DEBUG_FS */
+
 #endif
diff --git a/drivers/vfio/vfio_debugfs.c b/drivers/vfio/vfio_debugfs.c
new file mode 100644
index 000000000000..cd6c01437475
--- /dev/null
+++ b/drivers/vfio/vfio_debugfs.c
@@ -0,0 +1,80 @@
+// 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;
+
+	ret = vdev->mig_ops->migration_get_state(vdev, &state);
+	if (ret)
+		return -EINVAL;
+
+	switch (state) {
+	case VFIO_DEVICE_STATE_RUNNING:
+		seq_printf(seq, "%s\n", "RUNNING");
+		break;
+	case VFIO_DEVICE_STATE_STOP_COPY:
+		seq_printf(seq, "%s\n", "STOP_COPY");
+		break;
+	case VFIO_DEVICE_STATE_STOP:
+		seq_printf(seq, "%s\n", "STOP");
+		break;
+	case VFIO_DEVICE_STATE_RESUMING:
+		seq_printf(seq, "%s\n", "RESUMING");
+		break;
+	case VFIO_DEVICE_STATE_RUNNING_P2P:
+		seq_printf(seq, "%s\n", "RUNNING_P2P");
+		break;
+	case VFIO_DEVICE_STATE_ERROR:
+		seq_printf(seq, "%s\n", "ERROR");
+		break;
+	default:
+		seq_printf(seq, "%s\n", "Invalid");
+	}
+
+	return 0;
+}
+
+void vfio_device_debugfs_init(struct vfio_device *vdev)
+{
+	struct dentry *vfio_dev_migration = NULL;
+	struct device *dev = &vdev->device;
+
+	vdev->debug_root = debugfs_create_dir(dev_name(vdev->dev), vfio_debugfs_root);
+
+	if (vdev->mig_ops) {
+		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;
+}
+
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index cfad824d9aa2..8a7456f89842 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -309,7 +309,7 @@ static int __vfio_register_dev(struct vfio_device *device,
 
 	/* Refcounting can't start until the driver calls register */
 	refcount_set(&device->refcount, 1);
-
+	vfio_device_debugfs_init(device);
 	vfio_device_group_register(device);
 
 	return 0;
@@ -378,6 +378,7 @@ 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);
 }
@@ -1662,6 +1663,7 @@ 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;
 
@@ -1684,6 +1686,7 @@ static void __exit vfio_cleanup(void)
 	vfio_virqfd_exit();
 	vfio_group_cleanup();
 	xa_destroy(&vfio_device_set_xa);
+	vfio_debugfs_remove_root();
 }
 
 module_init(vfio_init);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 454e9295970c..769d7af86225 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -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
 };
 
 /**
-- 
2.24.0

[PATCH v15 2/2] Documentation: add debugfs description for vfio

[liulongfang]

From: Longfang Liu <liulongfang@huawei.com>

1.Add an debugfs document description file to help users understand
how to use the accelerator live migration driver's debugfs.
2.Update the file paths that need to be maintained in MAINTAINERS

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
---
 Documentation/ABI/testing/debugfs-vfio | 25 +++++++++++++++++++++++++
 MAINTAINERS                            |  1 +
 2 files changed, 26 insertions(+)
 create mode 100644 Documentation/ABI/testing/debugfs-vfio

diff --git a/Documentation/ABI/testing/debugfs-vfio b/Documentation/ABI/testing/debugfs-vfio
new file mode 100644
index 000000000000..086a8c52df35
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-vfio
@@ -0,0 +1,25 @@
+What:		/sys/kernel/debug/vfio
+Date:		Aug 2023
+KernelVersion:  6.6
+Contact:	Longfang Liu <liulongfang@huawei.com>
+Description:	This debugfs file directory is used for debugging
+		of vfio devices, it's a common directory for all vfio devices.
+		Each device should create a device subdirectory under this
+		directory by referencing the public registration interface.
+
+What:		/sys/kernel/debug/vfio/<device>/migration
+Date:		Aug 2023
+KernelVersion:  6.6
+Contact:	Longfang Liu <liulongfang@huawei.com>
+Description:	This debugfs file directory is used for debugging
+		of vfio devices that support live migration.
+		The debugfs of each vfio device that supports live migration
+		could be created under this directory.
+
+What:		/sys/kernel/debug/vfio/<device>/migration/state
+Date:		Aug 2023
+KernelVersion:  6.6
+Contact:	Longfang Liu <liulongfang@huawei.com>
+Description:	Read the live migration status of the vfio device.
+		The status of these live migrations includes:
+		ERROR, RUNNING, STOP, STOP_COPY, RESUMING.
diff --git a/MAINTAINERS b/MAINTAINERS
index 7b1306615fc0..bd01ca674c60 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22304,6 +22304,7 @@ L:	kvm@vger.kernel.org
 S:	Maintained
 T:	git https://github.com/awilliam/linux-vfio.git
 F:	Documentation/ABI/testing/sysfs-devices-vfio-dev
+F:	Documentation/ABI/testing/debugfs-vfio
 F:	Documentation/driver-api/vfio.rst
 F:	drivers/vfio/
 F:	include/linux/vfio.h
-- 
2.24.0

Re: [PATCH v15 0/2] add debugfs to migration driver

[liulongfang]

On 2023/9/1 10:36, liulongfang wrote:
> Add a debugfs function to the migration driver in VFIO to provide
> a step-by-step debugfs information for the migration driver.
> 
> Changes v14 -> v15
> 	Update the output status value of live migration.
> 
> Changes v13 -> v14
> 	Split the patchset and keep the vfio debugfs frame.
> 
> Changes v12 -> v13
> 	Solve the problem of open and close competition to debugfs.
> 
> Changes v11 -> v12
> 	Update loading conditions of vfio debugfs.
> 
> Changes v10 -> v11
> 	Delete the device restore function in debugfs.
> 
> Changes v9 -> v10
> 	Update the debugfs file of the live migration driver.
> 
> Changes v8 -> v9
> 	Update the debugfs directory structure of vfio.
> 
> Changes v7 -> v8
> 	Add support for platform devices.
> 
> Changes v6 -> v7
> 	Fix some code style issues.
> 
> Changes v5 -> v6
> 	Control the creation of debugfs through the CONFIG_DEBUG_FS.
> 
> Changes v4 -> v5
> 	Remove the newly added vfio_migration_ops and use seq_printf
> 	to optimize the implementation of debugfs.
> 
> Changes v3 -> v4
> 	Change the migration_debug_operate interface to debug_root file.
> 
> Changes v2 -> v3
> 	Extend the debugfs function from hisilicon device to vfio.
> 
> Changes v1 -> v2
> 	Change the registration method of root_debugfs to register
> 	with module initialization.
> 
> Longfang Liu (2):
>   vfio/migration: Add debugfs to live migration driver
>   Documentation: add debugfs description for vfio
> 
>  Documentation/ABI/testing/debugfs-vfio | 25 ++++++++
>  MAINTAINERS                            |  1 +
>  drivers/vfio/Makefile                  |  1 +
>  drivers/vfio/vfio.h                    | 14 +++++
>  drivers/vfio/vfio_debugfs.c            | 80 ++++++++++++++++++++++++++
>  drivers/vfio/vfio_main.c               |  5 +-
>  include/linux/vfio.h                   |  7 +++
>  7 files changed, 132 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/ABI/testing/debugfs-vfio
>  create mode 100644 drivers/vfio/vfio_debugfs.c
> 

Hi, Alex.
Is there anything else that needs to be modified in this patchset?

Thanks,
Longfang.

Re: [PATCH v15 1/2] vfio/migration: Add debugfs to live migration driver

[Alex Williamson]

On Fri, 1 Sep 2023 10:36:05 +0800
liulongfang <liulongfang@huawei.com> wrote:

> From: Longfang Liu <liulongfang@huawei.com>
> 
> 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"
> Finally, create a directory file based on the device type,
> and then create the device's own debugging files under
> this directory file.
> 
> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
> ---
>  drivers/vfio/Makefile       |  1 +
>  drivers/vfio/vfio.h         | 14 +++++++
>  drivers/vfio/vfio_debugfs.c | 80 +++++++++++++++++++++++++++++++++++++
>  drivers/vfio/vfio_main.c    |  5 ++-
>  include/linux/vfio.h        |  7 ++++
>  5 files changed, 106 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/vfio/vfio_debugfs.c
> 
> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
> index c82ea032d352..7934ac829989 100644
> --- a/drivers/vfio/Makefile
> +++ b/drivers/vfio/Makefile
> @@ -8,6 +8,7 @@ vfio-$(CONFIG_VFIO_GROUP) += group.o
>  vfio-$(CONFIG_IOMMUFD) += iommufd.o
>  vfio-$(CONFIG_VFIO_CONTAINER) += container.o
>  vfio-$(CONFIG_VFIO_VIRQFD) += virqfd.o
> +vfio-$(CONFIG_DEBUG_FS) += vfio_debugfs.o
>  
>  obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
>  obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 307e3f29b527..09b00757d0bb 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -448,4 +448,18 @@ static inline void vfio_device_put_kvm(struct vfio_device *device)
>  }
>  #endif
>  
> +#ifdef CONFIG_DEBUG_FS
> +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_DEBUG_FS */
> +
>  #endif
> diff --git a/drivers/vfio/vfio_debugfs.c b/drivers/vfio/vfio_debugfs.c
> new file mode 100644
> index 000000000000..cd6c01437475
> --- /dev/null
> +++ b/drivers/vfio/vfio_debugfs.c
> @@ -0,0 +1,80 @@
> +// 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;
> +
> +	ret = vdev->mig_ops->migration_get_state(vdev, &state);
> +	if (ret)
> +		return -EINVAL;
> +
> +	switch (state) {
> +	case VFIO_DEVICE_STATE_RUNNING:
> +		seq_printf(seq, "%s\n", "RUNNING");
> +		break;
> +	case VFIO_DEVICE_STATE_STOP_COPY:
> +		seq_printf(seq, "%s\n", "STOP_COPY");
> +		break;
> +	case VFIO_DEVICE_STATE_STOP:
> +		seq_printf(seq, "%s\n", "STOP");
> +		break;
> +	case VFIO_DEVICE_STATE_RESUMING:
> +		seq_printf(seq, "%s\n", "RESUMING");
> +		break;
> +	case VFIO_DEVICE_STATE_RUNNING_P2P:
> +		seq_printf(seq, "%s\n", "RUNNING_P2P");
> +		break;
> +	case VFIO_DEVICE_STATE_ERROR:
> +		seq_printf(seq, "%s\n", "ERROR");

Please order these the same as enum vfio_device_mig_state, we're also
missing a couple states, ie. PRE_COPY and PRE_COPY_P2P.  Can we use any
compiler tricks to create a build error when these are out of sync?

> +		break;
> +	default:
> +		seq_printf(seq, "%s\n", "Invalid");
> +	}
> +
> +	return 0;
> +}
> +
> +void vfio_device_debugfs_init(struct vfio_device *vdev)
> +{
> +	struct dentry *vfio_dev_migration = NULL;
> +	struct device *dev = &vdev->device;

Nit, both of these could be defined within the scope of the mig_ops
test below.

> +
> +	vdev->debug_root = debugfs_create_dir(dev_name(vdev->dev), vfio_debugfs_root);
> +
> +	if (vdev->mig_ops) {
> +		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;
> +}
> +
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index cfad824d9aa2..8a7456f89842 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -309,7 +309,7 @@ static int __vfio_register_dev(struct vfio_device *device,
>  
>  	/* Refcounting can't start until the driver calls register */
>  	refcount_set(&device->refcount, 1);
> -
> +	vfio_device_debugfs_init(device);
>  	vfio_device_group_register(device);
>  
>  	return 0;
> @@ -378,6 +378,7 @@ 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);
>  }

init/exit calls should try to be symmetric, if we call init before
vfio_device_group_register() then we should call exit after
vfio_device_group_unregister().  In this case, why shouldn't init be
the last call in __vfio_register_dev() and exit the first call in
vfio_unregister_group_dev()?

> @@ -1662,6 +1663,7 @@ 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;
>  
> @@ -1684,6 +1686,7 @@ static void __exit vfio_cleanup(void)
>  	vfio_virqfd_exit();
>  	vfio_group_cleanup();
>  	xa_destroy(&vfio_device_set_xa);
> +	vfio_debugfs_remove_root();
>  }

Same, if we create it last, let's remove it first.  The above creates
it last and removes it last.  Thanks,

Alex

>  
>  module_init(vfio_init);
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 454e9295970c..769d7af86225 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -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
>  };
>  
>  /**

Re: [PATCH v15 2/2] Documentation: add debugfs description for vfio

[Alex Williamson]

On Fri, 1 Sep 2023 10:36:06 +0800
liulongfang <liulongfang@huawei.com> wrote:

> From: Longfang Liu <liulongfang@huawei.com>
> 
> 1.Add an debugfs document description file to help users understand
> how to use the accelerator live migration driver's debugfs.
> 2.Update the file paths that need to be maintained in MAINTAINERS
> 
> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
> ---
>  Documentation/ABI/testing/debugfs-vfio | 25 +++++++++++++++++++++++++
>  MAINTAINERS                            |  1 +
>  2 files changed, 26 insertions(+)
>  create mode 100644 Documentation/ABI/testing/debugfs-vfio
> 
> diff --git a/Documentation/ABI/testing/debugfs-vfio b/Documentation/ABI/testing/debugfs-vfio
> new file mode 100644
> index 000000000000..086a8c52df35
> --- /dev/null
> +++ b/Documentation/ABI/testing/debugfs-vfio
> @@ -0,0 +1,25 @@
> +What:		/sys/kernel/debug/vfio
> +Date:		Aug 2023
> +KernelVersion:  6.6

This is all 6.7 material now and we might be conservative and mark it
for Oct 2023.

> +Contact:	Longfang Liu <liulongfang@huawei.com>
> +Description:	This debugfs file directory is used for debugging
> +		of vfio devices, it's a common directory for all vfio devices.
> +		Each device should create a device subdirectory under this
> +		directory by referencing the public registration interface.

The device sub-directory is already provided by the core.  Thanks,

Alex

> +
> +What:		/sys/kernel/debug/vfio/<device>/migration
> +Date:		Aug 2023
> +KernelVersion:  6.6
> +Contact:	Longfang Liu <liulongfang@huawei.com>
> +Description:	This debugfs file directory is used for debugging
> +		of vfio devices that support live migration.
> +		The debugfs of each vfio device that supports live migration
> +		could be created under this directory.
> +
> +What:		/sys/kernel/debug/vfio/<device>/migration/state
> +Date:		Aug 2023
> +KernelVersion:  6.6
> +Contact:	Longfang Liu <liulongfang@huawei.com>
> +Description:	Read the live migration status of the vfio device.
> +		The status of these live migrations includes:
> +		ERROR, RUNNING, STOP, STOP_COPY, RESUMING.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7b1306615fc0..bd01ca674c60 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22304,6 +22304,7 @@ L:	kvm@vger.kernel.org
>  S:	Maintained
>  T:	git https://github.com/awilliam/linux-vfio.git
>  F:	Documentation/ABI/testing/sysfs-devices-vfio-dev
> +F:	Documentation/ABI/testing/debugfs-vfio
>  F:	Documentation/driver-api/vfio.rst
>  F:	drivers/vfio/
>  F:	include/linux/vfio.h

Re: [PATCH v15 1/2] vfio/migration: Add debugfs to live migration driver

[liulongfang]

On 2023/9/16 5:00, Alex Williamson wrote:
> On Fri, 1 Sep 2023 10:36:05 +0800
> liulongfang <liulongfang@huawei.com> wrote:
> 
>> From: Longfang Liu <liulongfang@huawei.com>
>>
>> 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"
>> Finally, create a directory file based on the device type,
>> and then create the device's own debugging files under
>> this directory file.
>>
>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>> ---
>>  drivers/vfio/Makefile       |  1 +
>>  drivers/vfio/vfio.h         | 14 +++++++
>>  drivers/vfio/vfio_debugfs.c | 80 +++++++++++++++++++++++++++++++++++++
>>  drivers/vfio/vfio_main.c    |  5 ++-
>>  include/linux/vfio.h        |  7 ++++
>>  5 files changed, 106 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/vfio/vfio_debugfs.c
>>
>> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
>> index c82ea032d352..7934ac829989 100644
>> --- a/drivers/vfio/Makefile
>> +++ b/drivers/vfio/Makefile
>> @@ -8,6 +8,7 @@ vfio-$(CONFIG_VFIO_GROUP) += group.o
>>  vfio-$(CONFIG_IOMMUFD) += iommufd.o
>>  vfio-$(CONFIG_VFIO_CONTAINER) += container.o
>>  vfio-$(CONFIG_VFIO_VIRQFD) += virqfd.o
>> +vfio-$(CONFIG_DEBUG_FS) += vfio_debugfs.o
>>  
>>  obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
>>  obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
>> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
>> index 307e3f29b527..09b00757d0bb 100644
>> --- a/drivers/vfio/vfio.h
>> +++ b/drivers/vfio/vfio.h
>> @@ -448,4 +448,18 @@ static inline void vfio_device_put_kvm(struct vfio_device *device)
>>  }
>>  #endif
>>  
>> +#ifdef CONFIG_DEBUG_FS
>> +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_DEBUG_FS */
>> +
>>  #endif
>> diff --git a/drivers/vfio/vfio_debugfs.c b/drivers/vfio/vfio_debugfs.c
>> new file mode 100644
>> index 000000000000..cd6c01437475
>> --- /dev/null
>> +++ b/drivers/vfio/vfio_debugfs.c
>> @@ -0,0 +1,80 @@
>> +// 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;
>> +
>> +	ret = vdev->mig_ops->migration_get_state(vdev, &state);
>> +	if (ret)
>> +		return -EINVAL;
>> +
>> +	switch (state) {
>> +	case VFIO_DEVICE_STATE_RUNNING:
>> +		seq_printf(seq, "%s\n", "RUNNING");
>> +		break;
>> +	case VFIO_DEVICE_STATE_STOP_COPY:
>> +		seq_printf(seq, "%s\n", "STOP_COPY");
>> +		break;
>> +	case VFIO_DEVICE_STATE_STOP:
>> +		seq_printf(seq, "%s\n", "STOP");
>> +		break;
>> +	case VFIO_DEVICE_STATE_RESUMING:
>> +		seq_printf(seq, "%s\n", "RESUMING");
>> +		break;
>> +	case VFIO_DEVICE_STATE_RUNNING_P2P:
>> +		seq_printf(seq, "%s\n", "RUNNING_P2P");
>> +		break;
>> +	case VFIO_DEVICE_STATE_ERROR:
>> +		seq_printf(seq, "%s\n", "ERROR");
> 
> Please order these the same as enum vfio_device_mig_state, we're also
> missing a couple states, ie. PRE_COPY and PRE_COPY_P2P.  Can we use any
OK, I'll add them to the next version.

> compiler tricks to create a build error when these are out of sync?
>When these states are out of range, they should enter "default" processing.

>> +		break;
>> +	default:
>> +		seq_printf(seq, "%s\n", "Invalid");
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +void vfio_device_debugfs_init(struct vfio_device *vdev)
>> +{
>> +	struct dentry *vfio_dev_migration = NULL;
>> +	struct device *dev = &vdev->device;
> 
> Nit, both of these could be defined within the scope of the mig_ops
> test below.
>

"vfio_dev_migration" can be placed under mig_ops, but "dev" is public.
Also, there should be no problem declaring variables like this.

>> +
>> +	vdev->debug_root = debugfs_create_dir(dev_name(vdev->dev), vfio_debugfs_root);
>> +
>> +	if (vdev->mig_ops) {
>> +		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;
>> +}
>> +
>> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
>> index cfad824d9aa2..8a7456f89842 100644
>> --- a/drivers/vfio/vfio_main.c
>> +++ b/drivers/vfio/vfio_main.c
>> @@ -309,7 +309,7 @@ static int __vfio_register_dev(struct vfio_device *device,
>>  
>>  	/* Refcounting can't start until the driver calls register */
>>  	refcount_set(&device->refcount, 1);
>> -
>> +	vfio_device_debugfs_init(device);
>>  	vfio_device_group_register(device);
>>  
>>  	return 0;
>> @@ -378,6 +378,7 @@ 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);
>>  }
> 
> init/exit calls should try to be symmetric, if we call init before
> vfio_device_group_register() then we should call exit after
> vfio_device_group_unregister().  In this case, why shouldn't init be
> the last call in __vfio_register_dev() and exit the first call in
> vfio_unregister_group_dev()?
> 

OK, I would put vfio_device_debugfs_init() into vfio_device_group_register().

>> @@ -1662,6 +1663,7 @@ 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;
>>  
>> @@ -1684,6 +1686,7 @@ static void __exit vfio_cleanup(void)
>>  	vfio_virqfd_exit();
>>  	vfio_group_cleanup();
>>  	xa_destroy(&vfio_device_set_xa);
>> +	vfio_debugfs_remove_root();
>>  }
> 
> Same, if we create it last, let's remove it first.  The above creates
> it last and removes it last.  Thanks,
>

OK, I will adjust the order of vfio_debugfs_remove_root() in vfio_cleanup().

Thanks,
Longfang.

> Alex
> 
>>  
>>  module_init(vfio_init);
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>> index 454e9295970c..769d7af86225 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -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
>>  };
>>  
>>  /**
> 
> .
> 

Re: [PATCH v15 2/2] Documentation: add debugfs description for vfio

[liulongfang]

On 2023/9/16 5:00, Alex Williamson wrote:
> On Fri, 1 Sep 2023 10:36:06 +0800
> liulongfang <liulongfang@huawei.com> wrote:
> 
>> From: Longfang Liu <liulongfang@huawei.com>
>>
>> 1.Add an debugfs document description file to help users understand
>> how to use the accelerator live migration driver's debugfs.
>> 2.Update the file paths that need to be maintained in MAINTAINERS
>>
>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>> ---
>>  Documentation/ABI/testing/debugfs-vfio | 25 +++++++++++++++++++++++++
>>  MAINTAINERS                            |  1 +
>>  2 files changed, 26 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/debugfs-vfio
>>
>> diff --git a/Documentation/ABI/testing/debugfs-vfio b/Documentation/ABI/testing/debugfs-vfio
>> new file mode 100644
>> index 000000000000..086a8c52df35
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/debugfs-vfio
>> @@ -0,0 +1,25 @@
>> +What:		/sys/kernel/debug/vfio
>> +Date:		Aug 2023
>> +KernelVersion:  6.6
> 
> This is all 6.7 material now and we might be conservative and mark it
> for Oct 2023.
>
OK, I'll modify them all.

>> +Contact:	Longfang Liu <liulongfang@huawei.com>
>> +Description:	This debugfs file directory is used for debugging
>> +		of vfio devices, it's a common directory for all vfio devices.
>> +		Each device should create a device subdirectory under this
>> +		directory by referencing the public registration interface.
> 
> The device sub-directory is already provided by the core.  Thanks,
>

OK, I'll modify it.

Thanks,
Longfang.

> Alex
> 
>> +
>> +What:		/sys/kernel/debug/vfio/<device>/migration
>> +Date:		Aug 2023
>> +KernelVersion:  6.6
>> +Contact:	Longfang Liu <liulongfang@huawei.com>
>> +Description:	This debugfs file directory is used for debugging
>> +		of vfio devices that support live migration.
>> +		The debugfs of each vfio device that supports live migration
>> +		could be created under this directory.
>> +
>> +What:		/sys/kernel/debug/vfio/<device>/migration/state
>> +Date:		Aug 2023
>> +KernelVersion:  6.6
>> +Contact:	Longfang Liu <liulongfang@huawei.com>
>> +Description:	Read the live migration status of the vfio device.
>> +		The status of these live migrations includes:
>> +		ERROR, RUNNING, STOP, STOP_COPY, RESUMING.
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 7b1306615fc0..bd01ca674c60 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -22304,6 +22304,7 @@ L:	kvm@vger.kernel.org
>>  S:	Maintained
>>  T:	git https://github.com/awilliam/linux-vfio.git
>>  F:	Documentation/ABI/testing/sysfs-devices-vfio-dev
>> +F:	Documentation/ABI/testing/debugfs-vfio
>>  F:	Documentation/driver-api/vfio.rst
>>  F:	drivers/vfio/
>>  F:	include/linux/vfio.h
> 
> .
>