diff mbox series

[v5,1/5] vfio/migration: Add debugfs to live migration driver

Message ID 20221217063248.6735-2-liulongfang@huawei.com
State New
Headers
Series add debugfs to migration driver |

Commit Message

liulongfang Dec. 17, 2022, 6:32 a.m. UTC 
  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 VF |                | dst VF |
     +-+------+                +-+------+
       |   ^                     |   ^
       v   |                     v   |
 +-------+-+------+        +-------+-+------+
 |Debugfs|state   |        |Debugfs|state   |
 +-------+--------+        +-------+--------+
 |   debug_root   |        |   debug_root   |
 +-------+--------+        +-------+--------+

debugfs will create a public root directory "vfio_mig" file.
then create a "debug_root" file for each live migration VF device.
state file: used to get the status of the live migration device.
debug_root: used to create your own custom debug files for live
migration device drivers.

The live migration function of the current device can be tested by
operating the debug files, and the functional status of the equipment
and software at each stage can be tested step by step without
performing the complete live migration function. And after the live
migration is performed, the migration device data of the live migration
can be obtained through the debug files.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
---
 drivers/vfio/pci/Makefile           |  4 ++
 drivers/vfio/pci/vfio_pci_core.c    |  3 ++
 drivers/vfio/pci/vfio_pci_debugfs.c | 76 +++++++++++++++++++++++++++++
 drivers/vfio/pci/vfio_pci_debugfs.h | 30 ++++++++++++
 include/linux/vfio.h                |  6 +++
 5 files changed, 119 insertions(+)
 create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.c
 create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.h

Comments

Jason Gunthorpe Jan. 3, 2023, 3:05 p.m. UTC | #1 
On Sat, Dec 17, 2022 at 02:32:44PM +0800, Longfang Liu wrote:
> 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 VF |                | dst VF |
>      +-+------+                +-+------+
>        |   ^                     |   ^
>        v   |                     v   |
>  +-------+-+------+        +-------+-+------+
>  |Debugfs|state   |        |Debugfs|state   |
>  +-------+--------+        +-------+--------+
>  |   debug_root   |        |   debug_root   |
>  +-------+--------+        +-------+--------+
> 
> debugfs will create a public root directory "vfio_mig" file.
> then create a "debug_root" file for each live migration VF device.
> state file: used to get the status of the live migration device.
> debug_root: used to create your own custom debug files for live
> migration device drivers.
> 
> The live migration function of the current device can be tested by
> operating the debug files, and the functional status of the equipment
> and software at each stage can be tested step by step without
> performing the complete live migration function. And after the live
> migration is performed, the migration device data of the live migration
> can be obtained through the debug files.
> 
> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
> ---
>  drivers/vfio/pci/Makefile           |  4 ++
>  drivers/vfio/pci/vfio_pci_core.c    |  3 ++
>  drivers/vfio/pci/vfio_pci_debugfs.c | 76 +++++++++++++++++++++++++++++
>  drivers/vfio/pci/vfio_pci_debugfs.h | 30 ++++++++++++
>  include/linux/vfio.h                |  6 +++
>  5 files changed, 119 insertions(+)
>  create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.c
>  create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.h
> 
> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> index 24c524224da5..efe032623664 100644
> --- a/drivers/vfio/pci/Makefile
> +++ b/drivers/vfio/pci/Makefile
> @@ -4,6 +4,10 @@ vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_con
>  vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o
>  obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o
>  
> +ifneq ($(CONFIG_DEBUG_FS),)
> +	vfio-pci-core-y += vfio_pci_debugfs.o
> +endif

This is now how makefile should be written

vfio-pci-core-$(CONFIG_DEBUG_FS) += vfio_pci_debugfs.o

> +static int vfio_pci_vf_state_read(struct seq_file *seq, void *data)
> +{
> +	struct device *vf_dev = seq->private;
> +	struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev);
> +	struct vfio_device	*vdev = &core_device->vdev;
> +	enum vfio_device_mig_state state;
> +
> +	(void)vdev->mig_ops->migration_get_state(vdev, &state);

Do not use (void) like this, and why not handle the error?

> +	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", "RESUMING_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_pci_vf_debugfs_init(struct vfio_device *vdev)
> +{
> +	struct device *dev = vdev->dev;
> +
> +	vdev->debug_root = debugfs_create_dir(dev_name(dev), vfio_pci_debugfs_root);
> +
> +	debugfs_create_devm_seqfile(dev, "state", vdev->debug_root,
> +				  vfio_pci_vf_state_read);
> +}
> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_init);
> +
> +void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev)
> +{
> +	debugfs_remove_recursive(vdev->debug_root);
> +}
> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_exit);
> +
> +void  vfio_pci_debugfs_create_root(void)
> +{
> +	vfio_pci_debugfs_root = debugfs_create_dir("vfio_mig", NULL);
> +}
> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_create_root);
> +
> +void  vfio_pci_debugfs_remove_root(void)
> +{
> +	debugfs_remove_recursive(vfio_pci_debugfs_root);
> +	vfio_pci_debugfs_root = NULL;
> +}
> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_remove_root);

Why are these exported symbols? The core code should handle this on
its own.

If the device defines migration_get_state() then the debugfs should be
created.

Mabye you need an op to populate the driver's debugfs to also trigger
creating the directory

Jason
liulongfang Jan. 4, 2023, 3:10 a.m. UTC | #2 
On 2023/1/3 23:05, Jason Gunthorpe Wrote:
> On Sat, Dec 17, 2022 at 02:32:44PM +0800, Longfang Liu wrote:
>> 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 VF |                | dst VF |
>>      +-+------+                +-+------+
>>        |   ^                     |   ^
>>        v   |                     v   |
>>  +-------+-+------+        +-------+-+------+
>>  |Debugfs|state   |        |Debugfs|state   |
>>  +-------+--------+        +-------+--------+
>>  |   debug_root   |        |   debug_root   |
>>  +-------+--------+        +-------+--------+
>>
>> debugfs will create a public root directory "vfio_mig" file.
>> then create a "debug_root" file for each live migration VF device.
>> state file: used to get the status of the live migration device.
>> debug_root: used to create your own custom debug files for live
>> migration device drivers.
>>
>> The live migration function of the current device can be tested by
>> operating the debug files, and the functional status of the equipment
>> and software at each stage can be tested step by step without
>> performing the complete live migration function. And after the live
>> migration is performed, the migration device data of the live migration
>> can be obtained through the debug files.
>>
>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>> ---
>>  drivers/vfio/pci/Makefile           |  4 ++
>>  drivers/vfio/pci/vfio_pci_core.c    |  3 ++
>>  drivers/vfio/pci/vfio_pci_debugfs.c | 76 +++++++++++++++++++++++++++++
>>  drivers/vfio/pci/vfio_pci_debugfs.h | 30 ++++++++++++
>>  include/linux/vfio.h                |  6 +++
>>  5 files changed, 119 insertions(+)
>>  create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.c
>>  create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.h
>>
>> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
>> index 24c524224da5..efe032623664 100644
>> --- a/drivers/vfio/pci/Makefile
>> +++ b/drivers/vfio/pci/Makefile
>> @@ -4,6 +4,10 @@ vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_con
>>  vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o
>>  obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o
>>  
>> +ifneq ($(CONFIG_DEBUG_FS),)
>> +	vfio-pci-core-y += vfio_pci_debugfs.o
>> +endif
> 
> This is now how makefile should be written
> 
> vfio-pci-core-$(CONFIG_DEBUG_FS) += vfio_pci_debugfs.o
> 

Ok, here it will be changed on the next patch version.

>> +static int vfio_pci_vf_state_read(struct seq_file *seq, void *data)
>> +{
>> +	struct device *vf_dev = seq->private;
>> +	struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev);
>> +	struct vfio_device	*vdev = &core_device->vdev;
>> +	enum vfio_device_mig_state state;
>> +
>> +	(void)vdev->mig_ops->migration_get_state(vdev, &state);
> 
> Do not use (void) like this, and why not handle the error?
> 

Ok, here I will add an error handling.

>> +	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", "RESUMING_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_pci_vf_debugfs_init(struct vfio_device *vdev)
>> +{
>> +	struct device *dev = vdev->dev;
>> +
>> +	vdev->debug_root = debugfs_create_dir(dev_name(dev), vfio_pci_debugfs_root);
>> +
>> +	debugfs_create_devm_seqfile(dev, "state", vdev->debug_root,
>> +				  vfio_pci_vf_state_read);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_init);
>> +
>> +void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev)
>> +{
>> +	debugfs_remove_recursive(vdev->debug_root);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_exit);
>> +
>> +void  vfio_pci_debugfs_create_root(void)
>> +{
>> +	vfio_pci_debugfs_root = debugfs_create_dir("vfio_mig", NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_create_root);
>> +
>> +void  vfio_pci_debugfs_remove_root(void)
>> +{
>> +	debugfs_remove_recursive(vfio_pci_debugfs_root);
>> +	vfio_pci_debugfs_root = NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_remove_root);
> 
> Why are these exported symbols? The core code should handle this on
> its own.
> 

I included this set of interfaces through the #ifdef CONFIG_DEBUG_FS macro
in vfio_pci_debugfs.h.
If EXPORT_SYMBOL_GPL is not added here, a compilation error will appear:

ERROR: modpost: "vfio_pci_vf_debugfs_exit" [drivers/vfio/pci/hisilicon/hisi-acc-vfio-pci.ko] undefined!
ERROR: modpost: "vfio_pci_vf_debugfs_init" [drivers/vfio/pci/hisilicon/hisi-acc-vfio-pci.ko] undefined!
scripts/Makefile.modpost:126: recipe for target 'Module.symvers' failed

> If the device defines migration_get_state() then the debugfs should be
> created.
> 

The trigger strategy created by the current debugfs is determined in the device
driver according to the setting method of vfio_device_ops.
If vfio_device_ops is enabled with live migration, then its migration_get_state()
will also be enabled.

> Mabye you need an op to populate the driver's debugfs to also trigger
> creating the directory
>

It is also possible to put this trigger strategy in the corresponding device driver, right?
Putting this strategy in this public vfio_pci_debugfs.c will also increase the implementation
complexity of this function.

> Jason
> .
> 
Thanks,
Longfang.
diff mbox series

Patch

diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
index 24c524224da5..efe032623664 100644
--- a/drivers/vfio/pci/Makefile
+++ b/drivers/vfio/pci/Makefile
@@ -4,6 +4,10 @@  vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_con
 vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o
 obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o
 
+ifneq ($(CONFIG_DEBUG_FS),)
+	vfio-pci-core-y += vfio_pci_debugfs.o
+endif
+
 vfio-pci-y := vfio_pci.o
 vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
 obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index f9365a5bc961..e85df2deb8e6 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -31,6 +31,7 @@ 
 #include <asm/eeh.h>
 #endif
 
+#include "vfio_pci_debugfs.h"
 #include "vfio_pci_priv.h"
 
 #define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@redhat.com>"
@@ -2555,11 +2556,13 @@  EXPORT_SYMBOL_GPL(vfio_pci_core_set_params);
 
 static void vfio_pci_core_cleanup(void)
 {
+	vfio_pci_debugfs_remove_root();
 	vfio_pci_uninit_perm_bits();
 }
 
 static int __init vfio_pci_core_init(void)
 {
+	vfio_pci_debugfs_create_root();
 	/* Allocate shared config space permission data used by all devices */
 	return vfio_pci_init_perm_bits();
 }
diff --git a/drivers/vfio/pci/vfio_pci_debugfs.c b/drivers/vfio/pci/vfio_pci_debugfs.c
new file mode 100644
index 000000000000..33d663fb04f2
--- /dev/null
+++ b/drivers/vfio/pci/vfio_pci_debugfs.c
@@ -0,0 +1,76 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022, HiSilicon Ltd.
+ */
+
+#include <linux/pci.h>
+#include <linux/vfio_pci_core.h>
+
+#include "vfio_pci_debugfs.h"
+
+static struct dentry *vfio_pci_debugfs_root;
+
+static int vfio_pci_vf_state_read(struct seq_file *seq, void *data)
+{
+	struct device *vf_dev = seq->private;
+	struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev);
+	struct vfio_device	*vdev = &core_device->vdev;
+	enum vfio_device_mig_state state;
+
+	(void)vdev->mig_ops->migration_get_state(vdev, &state);
+	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", "RESUMING_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_pci_vf_debugfs_init(struct vfio_device *vdev)
+{
+	struct device *dev = vdev->dev;
+
+	vdev->debug_root = debugfs_create_dir(dev_name(dev), vfio_pci_debugfs_root);
+
+	debugfs_create_devm_seqfile(dev, "state", vdev->debug_root,
+				  vfio_pci_vf_state_read);
+}
+EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_init);
+
+void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev)
+{
+	debugfs_remove_recursive(vdev->debug_root);
+}
+EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_exit);
+
+void  vfio_pci_debugfs_create_root(void)
+{
+	vfio_pci_debugfs_root = debugfs_create_dir("vfio_mig", NULL);
+}
+EXPORT_SYMBOL_GPL(vfio_pci_debugfs_create_root);
+
+void  vfio_pci_debugfs_remove_root(void)
+{
+	debugfs_remove_recursive(vfio_pci_debugfs_root);
+	vfio_pci_debugfs_root = NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_pci_debugfs_remove_root);
+
diff --git a/drivers/vfio/pci/vfio_pci_debugfs.h b/drivers/vfio/pci/vfio_pci_debugfs.h
new file mode 100644
index 000000000000..8d1a4aef05db
--- /dev/null
+++ b/drivers/vfio/pci/vfio_pci_debugfs.h
@@ -0,0 +1,30 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * vfio_pci_debugfs.h - VFIO migration debugfs interface
+ *
+ * Copyright (c) 2022, HiSilicon Ltd.
+ *
+ * Author: Longfang Liu <liulongfang@huawei.com>
+ */
+
+#ifndef __VFIO_PCI_DEBUGFS_H
+#define __VFIO_PCI_DEBUGFS_H
+
+#include <linux/debugfs.h>
+#include <linux/vfio.h>
+
+#ifdef CONFIG_DEBUG_FS
+void  vfio_pci_debugfs_create_root(void);
+void  vfio_pci_debugfs_remove_root(void);
+
+void vfio_pci_vf_debugfs_init(struct vfio_device *vdev);
+void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev);
+#else
+static inline void vfio_pci_debugfs_create_root(void) { }
+static inline void vfio_pci_debugfs_remove_root(void) { }
+
+static inline void vfio_pci_vf_debugfs_init(struct vfio_device *vdev) { }
+static inline void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev) { }
+#endif /* CONFIG_DEBUG_FS */
+
+#endif /* __VFIO_PCI_DEBUGFS_H */
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b4d5d4ca3d7d..7d6d02f165cf 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -54,6 +54,12 @@  struct vfio_device {
 	struct completion comp;
 	struct list_head group_next;
 	struct list_head iommu_entry;
+
+	/*
+	 * debug_root is a static property of the vfio_device
+	 * which must be set prior to registering the vfio_device.
+	 */
+	struct dentry *debug_root;
 };
 
 /**