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Date: Tue, 14 Mar 2023 17:42:03 +0800
From: liulongfang <liulongfang@...wei.com>
To: Alex Williamson <alex.williamson@...hat.com>
CC: <jgg@...dia.com>, <shameerali.kolothum.thodi@...wei.com>,
<jonathan.cameron@...wei.com>, <cohuck@...hat.com>,
<linux-kernel@...r.kernel.org>, <linuxarm@...neuler.org>
Subject: Re: [PATCH v8 1/5] vfio/migration: Add debugfs to live migration
driver
On 2023/3/11 7:40, Alex Williamson wrote:
> On Fri, 17 Feb 2023 16:48:27 +0800
> Longfang Liu <liulongfang@...wei.com> 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 |
>> | |
>> | |
>> +---+----------------------------+----------+
>> | ^ | ^
>> | | | |
>> +--------+ | | | |
>> | vfio | v | v |
>> +--------+ +---------+--+ +---------+--+
>> ^ |src vfio_dev| |dst vfio_dev|
>> | +--+---------+ +--+---------+
>> | | ^ | ^
>> | | | | |
>> | v | | |
>> | +-----------+ +-----------+----+ | |
>> +--+<bdf>file_x+<----+---+migration_attr | | |
>> | +-----------+ | +----------------+ | |
>> | +---+migration_data | | |
>> | | +----------------+ | |
>> | +---+migration_debug | | |
>> | | +----------------+ | |
>> | | +----------------+ | |
>> | +---+migration_state | | |
>> | +----------------+ | |
>> | | |
>> | +-----------+ +----------------+ | |
>> +--+<bdf>file_y|<----+---+migration_attr | | |
>> +-----------+ | +----------------+ | |
>> +---+migration_data | | |
>> | +----------------+<---------------+ |
>> +---+migration_debug | |
>> | +----------------+ |
>> | +----------------+ |
>> +---+migration_state +-----------------------+
>> +----------------+
>>
>> 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.
>>
>> debugfs will create a public root directory "vfio" file.
>> then create a device <bdf> named file for each live migration device.
>
> dev_name(), it's only <sbdf> for PCI devices.
>
Yes, this description needs revision.
>> First, create a unified state acquisition file of "migration_state"
>> in this device directory.
>> Then, create your own debugging files independently according to
>> the functional requirements of each device.
>>
>> Here, HiSilicon accelerator creates three debug files:
>> migration_attr: used to obtain the attribute parameters of the
>> current live migration device.
>> migration_data: used to get the live migration data of the current
>> live migration device.
>> migration_debug: Used to debug the current live migration device
>> through commands.
>>
>> 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@...wei.com>
>> ---
>> drivers/vfio/Makefile | 2 +-
>> drivers/vfio/vfio.h | 14 +++++++
>> drivers/vfio/vfio_debugfs.c | 82 +++++++++++++++++++++++++++++++++++++
>> drivers/vfio/vfio_main.c | 5 +++
>> include/linux/vfio.h | 8 ++++
>> 5 files changed, 110 insertions(+), 1 deletion(-)
>> create mode 100644 drivers/vfio/vfio_debugfs.c
>>
>> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
>> index 70e7dcb302ef..1debcff31d30 100644
>> --- a/drivers/vfio/Makefile
>> +++ b/drivers/vfio/Makefile
>> @@ -7,7 +7,7 @@ vfio-y += vfio_main.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
>> obj-$(CONFIG_VFIO_PCI) += pci/
>> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
>> index e9721d8424bc..66c00f97e9cc 100644
>> --- a/drivers/vfio/vfio.h
>> +++ b/drivers/vfio/vfio.h
>> @@ -258,4 +258,18 @@ 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_vf_debugfs_init(struct vfio_device *vdev);
>> +void vfio_vf_debugfs_exit(struct vfio_device *vdev);
>
> s/vf_// throughout.
>
Yes, it is not vf anymore, the function name needs to be modified
>> +#else
>> +static inline void vfio_debugfs_create_root(void) { }
>> +static inline void vfio_debugfs_remove_root(void) { }
>> +
>> +static inline void vfio_vf_debugfs_init(struct vfio_device *vdev) { }
>> +static inline void vfio_vf_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..c5df1496fe0e
>> --- /dev/null
>> +++ b/drivers/vfio/vfio_debugfs.c
>> @@ -0,0 +1,82 @@
>> +// 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_vf_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) {
>> + dev_err(vf_dev, "failed to get device migration state");
>
> Isn't the errno below sufficient? No need to add the ability to fill
> logs as well.
>
OK，I will remove it in the next version.
>> + 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", "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_vf_debugfs_init(struct vfio_device *vdev)
>> +{
>> + struct device *dev = &vdev->device;
>> +
>> + vdev->debug_root = debugfs_create_dir(dev_name(vdev->dev), vfio_debugfs_root);
>> +
>> + debugfs_create_devm_seqfile(dev, "migration_state", vdev->debug_root,
>> + vfio_vf_state_read);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_vf_debugfs_init);
>> +
>> +void vfio_vf_debugfs_exit(struct vfio_device *vdev)
>> +{
>> + debugfs_remove_recursive(vdev->debug_root);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_vf_debugfs_exit);
>
> The above two should probably be vfio_device_debugfs_{init,exit}().
>
OK
>> +
>> +void vfio_debugfs_create_root(void)
>> +{
>> + vfio_debugfs_root = debugfs_create_dir("vfio", NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_debugfs_create_root);
>> +
>> +void vfio_debugfs_remove_root(void)
>> +{
>> + debugfs_remove_recursive(vfio_debugfs_root);
>> + vfio_debugfs_root = NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(vfio_debugfs_remove_root);
>
> As Jason notes, this becomes part of the vfio module, these latter two
> don't need to be exported to be called by vfio_main.
>
Let me re-debug to see if I can delete the following exports
> Thanks,
> Alex
>
Thanks，
Longfang
>> +
>> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
>> index 3a597e799918..09772fd3a396 100644
>> --- a/drivers/vfio/vfio_main.c
>> +++ b/drivers/vfio/vfio_main.c
>> @@ -1408,6 +1408,9 @@ static int __init vfio_init(void)
>> }
>>
>> pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
>> +
>> + vfio_debugfs_create_root();
>> +
>> return 0;
>>
>> err_dev_class:
>> @@ -1425,6 +1428,8 @@ 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 93134b023968..fa6b898ebb58 100644
>> --- a/include/linux/vfio.h
>> +++ b/include/linux/vfio.h
>> @@ -63,6 +63,14 @@ struct vfio_device {
>> struct iommufd_ctx *iommufd_ictx;
>> bool iommufd_attached;
>> #endif
>> +
>> +#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
>> };
>>
>> /**
>
> .
>
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