Date:   Tue, 14 Mar 2023 19:21:29 +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 3/5] hisi_acc_vfio_pci: register debugfs for hisilicon
 migration driver

On 2023/3/14 19:04, liulongfang wrote:
> On 2023/3/11 7:40, Alex Williamson wrote:
>> On Fri, 17 Feb 2023 16:48:29 +0800
>> Longfang Liu <liulongfang@...wei.com> wrote:
>>
>>> On the debugfs framework of VFIO, if the CONFIG_DEBUG_FS macro is
>>> enabled, the debug function is registered for the live migration driver
>>> of the HiSilicon accelerator device.
>>>
>>> On the basis of the original public debug function, a private debug
>>> function is added:
>>>
>>> mig_data file: used to get the migration data of the live migration device
>>> mig_attr file: used to get device attributes of the live migration device
>>> debug file: used to test for acquiring and writing device state data
>>> for VF device.
>>>
>>> Signed-off-by: Longfang Liu <liulongfang@...wei.com>
>>> ---
>>>  .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    | 282 ++++++++++++++++++
>>>  .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h    |  11 +
>>>  2 files changed, 293 insertions(+)
>>>
>>> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> index a1589947e721..a0ecb1cd5707 100644
>>> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> @@ -15,6 +15,7 @@
>>>  #include <linux/anon_inodes.h>
>>>  
>>>  #include "hisi_acc_vfio_pci.h"
>>> +#include "../../vfio.h"
>>>  
>>>  /* Return 0 on VM acc device ready, -ETIMEDOUT hardware timeout */
>>>  static int qm_wait_dev_not_ready(struct hisi_qm *qm)
>>> @@ -606,6 +607,18 @@ hisi_acc_check_int_state(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>>  	}
>>>  }
>>>  
>>> +static void hisi_acc_vf_migf_save(struct hisi_acc_vf_migration_file *src_migf,
>>> +	struct hisi_acc_vf_migration_file *dst_migf)
>>> +{
>>> +	if (!dst_migf)
>>> +		return;
>>> +
>>> +	dst_migf->disabled = false;
>>> +	dst_migf->total_length = src_migf->total_length;
>>> +	memcpy(&dst_migf->vf_data, &src_migf->vf_data,
>>> +		    sizeof(struct acc_vf_data));
>>> +}
>>> +
>>>  static void hisi_acc_vf_disable_fd(struct hisi_acc_vf_migration_file *migf)
>>>  {
>>>  	mutex_lock(&migf->lock);
>>> @@ -618,12 +631,16 @@ static void hisi_acc_vf_disable_fd(struct hisi_acc_vf_migration_file *migf)
>>>  static void hisi_acc_vf_disable_fds(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>>  {
>>>  	if (hisi_acc_vdev->resuming_migf) {
>>> +		hisi_acc_vf_migf_save(hisi_acc_vdev->resuming_migf,
>>> +						hisi_acc_vdev->debug_migf);
>>>  		hisi_acc_vf_disable_fd(hisi_acc_vdev->resuming_migf);
>>>  		fput(hisi_acc_vdev->resuming_migf->filp);
>>>  		hisi_acc_vdev->resuming_migf = NULL;
>>>  	}
>>>  
>>>  	if (hisi_acc_vdev->saving_migf) {
>>> +		hisi_acc_vf_migf_save(hisi_acc_vdev->saving_migf,
>>> +						hisi_acc_vdev->debug_migf);
>>>  		hisi_acc_vf_disable_fd(hisi_acc_vdev->saving_migf);
>>>  		fput(hisi_acc_vdev->saving_migf->filp);
>>>  		hisi_acc_vdev->saving_migf = NULL;
>>> @@ -1303,6 +1320,265 @@ static long hisi_acc_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int
>>>  	return vfio_pci_core_ioctl(core_vdev, cmd, arg);
>>>  }
>>>  
>>> +static int hisi_acc_vf_debug_io(struct vfio_device *vdev)
>>> +{
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
>>> +	struct device *dev = vdev->dev;
>>> +	u64 data;
>>> +	int ret;
>>> +
>>> +	ret = qm_wait_dev_not_ready(vf_qm);
>>> +	if (ret)
>>> +		dev_err(dev, "VF device not ready!\n");
>>> +
>>> +	data = readl(vf_qm->io_base + QM_MB_CMD_SEND_BASE);
>>> +	dev_info(dev, "debug mailbox val: 0x%llx\n", data);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int hisi_acc_vf_debug_resume(struct vfio_device *vdev)
>>> +{
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf;
>>> +	struct device *dev = vdev->dev;
>>> +	int ret;
>>> +
>>> +	ret = vf_qm_state_save(hisi_acc_vdev, migf);
>>> +	if (ret) {
>>> +		dev_err(dev, "failed to save device data!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	ret = vf_qm_check_match(hisi_acc_vdev, migf);
>>> +	if (ret) {
>>> +		dev_err(dev, "failed to match the VF!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	ret = vf_qm_load_data(hisi_acc_vdev, migf);
>>> +	if (ret) {
>>> +		dev_err(dev, "failed to recover the VF!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	vf_qm_fun_reset(&hisi_acc_vdev->vf_qm);
>>> +	dev_info(dev, "successful to resume device data!\n");
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vf_debug_save(struct vfio_device *vdev)
>>> +{
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf;
>>> +	struct device *dev = vdev->dev;
>>> +	int ret;
>>> +
>>> +	ret = vf_qm_state_save(hisi_acc_vdev, migf);
>>> +	if (ret) {
>>> +		dev_err(dev, "failed to save device data!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +	dev_info(dev, "successful to save device data!\n");
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int
>>> +hisi_acc_vf_debug_operate(struct vfio_device *vdev, unsigned int cmd)
>>> +{
>>> +	int ret;
>>> +
>>> +	switch (cmd) {
>>> +	case STATE_SAVE:
>>> +		ret = hisi_acc_vf_debug_save(vdev);
>>> +		if (ret)
>>> +			return ret;
>>> +		break;
>>> +	case STATE_RESUME:
>>> +		ret = hisi_acc_vf_debug_resume(vdev);
>>> +		if (ret)
>>> +			return ret;
>>> +		break;
>>> +	case RW_IO_TEST:
>>> +		ret = hisi_acc_vf_debug_io(vdev);
>>> +		if (ret)
>>> +			return ret;
>>> +		break;
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vf_debug_check(struct vfio_device *vdev)
>>> +{
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf;
>>> +	enum vfio_device_mig_state state;
>>> +
>>> +	if (!vdev->mig_ops || !migf) {
>>> +		dev_err(vdev->dev, "device not support debugfs!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	/* If device not opened, the debugfs operation will trigger calltrace */
>>> +	(void)vdev->mig_ops->migration_get_state(vdev, &state);
>>> +	if (state == VFIO_DEVICE_STATE_ERROR ||
>>> +	    state == VFIO_DEVICE_STATE_STOP) {
>>> +		dev_err(vdev->dev, "device not opened!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static ssize_t hisi_acc_vf_debug_write(struct file *filp, const char __user *buffer,
>>> +			    size_t count, loff_t *pos)
>>> +{
>>> +	struct vfio_device	*vdev = filp->private_data;
>>> +	char tbuf[VFIO_DEV_DBG_LEN];
>>> +	unsigned long cmd;
>>> +	int len, ret;
>>> +
>>> +	if (*pos)
>>> +		return 0;
>>> +
>>> +	if (count >= VFIO_DEV_DBG_LEN)
>>> +		return -ENOSPC;
>>> +
>>> +	ret = hisi_acc_vf_debug_check(vdev);
>>> +	if (ret)
>>> +		return -EINVAL;
>>> +
>>> +	len = simple_write_to_buffer(tbuf, VFIO_DEV_DBG_LEN - 1,
>>> +					pos, buffer, count);
>>> +	if (len < 0 || len > VFIO_DEV_DBG_LEN - 1)
>>> +		return -EINVAL;
>>> +	tbuf[len] = '\0';
>>> +	if (kstrtoul(tbuf, 0, &cmd))
>>> +		return -EFAULT;
>>> +
>>> +	ret = hisi_acc_vf_debug_operate(vdev, cmd);
>>> +	if (ret) {
>>> +		dev_err(vdev->dev, "device debug test failed!\n");
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	return count;
>>> +}
>>> +
>>> +static const struct file_operations hisi_acc_vf_debug_fops = {
>>> +	.owner = THIS_MODULE,
>>> +	.open = simple_open,
>>> +	.write = hisi_acc_vf_debug_write,
>>> +};
>>> +
>>> +static void seq_print_hex_data(struct seq_file *seq, const void *buf, size_t len)
>>> +{
>>> +#define HEX_LINE_SIZE		131
>>> +#define HEX_ROW_SIZE		16
>>> +	unsigned char linebuf[HEX_LINE_SIZE];
>>> +	int i, linelen, remaining = len;
>>> +	const u8 *ptr = buf;
>>> +
>>> +	for (i = 0; i < len; i += HEX_ROW_SIZE) {
>>> +		linelen = min(remaining, HEX_ROW_SIZE);
>>> +		remaining -= HEX_ROW_SIZE;
>>> +
>>> +		hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE, 1,
>>> +					linebuf, sizeof(linebuf), false);
>>> +
>>> +		seq_printf(seq, "%s%.8x: %s\n", "Mig Data:", i, linebuf);
>>> +	}
>>> +}
>>> +
>>> +static int hisi_acc_vf_data_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;
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_acc_vf_migration_file *debug_migf = hisi_acc_vdev->debug_migf;
>>> +	size_t vf_data_sz = offsetofend(struct acc_vf_data, padding);
>>> +
>>> +	if (debug_migf && debug_migf->total_length)
>>> +		seq_print_hex_data(seq, (unsigned char *)&debug_migf->vf_data,
>>> +				vf_data_sz);
>>> +	else
>>> +		seq_printf(seq, "%s\n", "device not migrated!");
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vf_attr_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;
>>> +	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev);
>>> +	struct hisi_acc_vf_migration_file *debug_migf = hisi_acc_vdev->debug_migf;
>>> +
>>> +	if (debug_migf && debug_migf->total_length) {
>>> +		seq_printf(seq,
>>> +			 "acc device:\n"
>>> +			 "device  state: %d\n"
>>> +			 "device  ready: %u\n"
>>> +			 "data    valid: %d\n"
>>> +			 "data     size: %lu\n",
>>> +			 hisi_acc_vdev->mig_state,
>>> +			 hisi_acc_vdev->vf_qm_state,
>>> +			 debug_migf->disabled,
>>> +			 debug_migf->total_length);
>>> +	} else {
>>> +		seq_printf(seq, "%s\n", "device not migrated!");
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vfio_debug_init(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>> +{
>>> +	struct vfio_device *vdev = &hisi_acc_vdev->core_device.vdev;
>>> +	struct device *dev = vdev->dev;
>>> +	void *migf = NULL;
>>> +
>>> +	if (!debugfs_initialized())
>>> +		return 0;
>>> +
>>> +	vfio_vf_debugfs_init(vdev);
>>> +
>>> +	migf = kzalloc(sizeof(struct hisi_acc_vf_migration_file), GFP_KERNEL);
>>> +	if (!migf)
>>> +		return -ENOMEM;
>>> +
>>> +	hisi_acc_vdev->debug_migf = migf;
>>> +
>>> +	debugfs_create_devm_seqfile(dev, "migration_data", vdev->debug_root,
>>> +				  hisi_acc_vf_data_read);
>>> +	debugfs_create_devm_seqfile(dev, "migration_attr", vdev->debug_root,
>>> +				  hisi_acc_vf_attr_read);
>>> +
>>> +	debugfs_create_file("migration_debug", 0200, vdev->debug_root,
>>> +				  vdev, &hisi_acc_vf_debug_fops);
>>> +
>>
>> All of these are going to be device specific, right?  So do we really
>> want a debugfs file structure that looks like:
>>
>> vfio
>> └── migration
>>     ├── hisi_acc
>>     │   ├── attr
>>     │   ├── data
>>     │   └── debug
>>     └── state
>>
> 
> According to this directory structure, I also need to change.
> 
> Thanks
> Longfang.

If there are multiple devices participating in live migration, their current directory structure
is like this:
vfio
├── hisi_acc_1
│     ├── attr
│     ├── data
│     ├── debug
│     └── state
│
└── hisi_acc_2
       ├── attr
       ├── data
       ├── debug
       └── state


If you want to change to the above directory structure, which directory should the
‘state’ file be placed in the case of multiple devices?
vfio
 └─ migration
     ├── hisi_acc
     │     ├── attr
     │     ├── data
     │     └── debug
     └── state

Like this or other directory structure?
vfio
└─ migration
    ├── hisi_acc_1
    │     ├── attr
    │     ├── data
    │     └── debug
    ├── hisi_acc_2
    │     ├── attr
    │     ├── data
    │     └── debug
    └── state
	   ├── hisi_acc_1
	   └── hisi_acc_2

Thanks，
Longfang.

>> Thanks,
>> Alex
>>
>>> +	return 0;
>>> +}
>>> +
>>> +static void hisi_acc_vf_debugfs_exit(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>> +{
>>> +	struct vfio_device *vdev = &hisi_acc_vdev->core_device.vdev;
>>> +
>>> +	if (!debugfs_initialized())
>>> +		return;
>>> +
>>> +	vfio_vf_debugfs_exit(vdev);
>>> +	kfree(hisi_acc_vdev->debug_migf);
>>> +}
>>> +
>>>  static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
>>>  {
>>>  	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev);
>>> @@ -1416,6 +1692,9 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device
>>>  	if (IS_ERR(hisi_acc_vdev))
>>>  		return PTR_ERR(hisi_acc_vdev);
>>>  
>>> +	if (ops == &hisi_acc_vfio_pci_migrn_ops)
>>> +		hisi_acc_vfio_debug_init(hisi_acc_vdev);
>>> +
>>>  	dev_set_drvdata(&pdev->dev, &hisi_acc_vdev->core_device);
>>>  	ret = vfio_pci_core_register_device(&hisi_acc_vdev->core_device);
>>>  	if (ret)
>>> @@ -1423,6 +1702,8 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device
>>>  	return 0;
>>>  
>>>  out_put_vdev:
>>> +	if (ops == &hisi_acc_vfio_pci_migrn_ops)
>>> +		hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
>>>  	vfio_put_device(&hisi_acc_vdev->core_device.vdev);
>>>  	return ret;
>>>  }
>>> @@ -1431,6 +1712,7 @@ static void hisi_acc_vfio_pci_remove(struct pci_dev *pdev)
>>>  {
>>>  	struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev);
>>>  
>>> +	hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
>>>  	vfio_pci_core_unregister_device(&hisi_acc_vdev->core_device);
>>>  	vfio_put_device(&hisi_acc_vdev->core_device.vdev);
>>>  }
>>> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
>>> index dcabfeec6ca1..ef50b12f018d 100644
>>> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
>>> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
>>> @@ -49,6 +49,14 @@
>>>  #define QM_EQC_DW0		0X8000
>>>  #define QM_AEQC_DW0		0X8020
>>>  
>>> +#define VFIO_DEV_DBG_LEN		256
>>> +
>>> +enum mig_debug_cmd {
>>> +	STATE_SAVE,
>>> +	STATE_RESUME,
>>> +	RW_IO_TEST,
>>> +};
>>> +
>>>  struct acc_vf_data {
>>>  #define QM_MATCH_SIZE offsetofend(struct acc_vf_data, qm_rsv_state)
>>>  	/* QM match information */
>>> @@ -113,5 +121,8 @@ struct hisi_acc_vf_core_device {
>>>  	spinlock_t reset_lock;
>>>  	struct hisi_acc_vf_migration_file *resuming_migf;
>>>  	struct hisi_acc_vf_migration_file *saving_migf;
>>> +
>>> +	/* For debugfs */
>>> +	struct hisi_acc_vf_migration_file *debug_migf;
>>>  };
>>>  #endif /* HISI_ACC_VFIO_PCI_H */
>>
>> .
>>

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