Re: [PATCH v11 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver

liulongfang
2024-11-04T08:31:27Z

On 2024/11/4 15:54, liulongfang wrote:
> On 2024/11/1 6:04, Alex Williamson wrote:
>> On Fri, 25 Oct 2024 17:01:42 +0800
>> Longfang Liu <liulongfang@huawei.com> wrote:
>>
>>> On the debugfs framework of VFIO, if the CONFIG_VFIO_DEBUGFS macro is
>>> enabled, the debug function is registered for the live migration driver
>>> of the HiSilicon accelerator device.
>>>
>>> After registering the HiSilicon accelerator device on the debugfs
>>> framework of live migration of vfio, a directory file "hisi_acc"
>>> of debugfs is created, and then three debug function files are
>>> created in this directory:
>>>
>>> vfio
>>> |
>>> +---<dev_name1>
>>> | +---migration
>>> | +--state
>>> | +--hisi_acc
>>> | +--dev_data
>>> | +--migf_data
>>> | +--cmd_state
>>> |
>>> +---<dev_name2>
>>> +---migration
>>> +--state
>>> +--hisi_acc
>>> +--dev_data
>>> +--migf_data
>>> +--cmd_state
>>>
>>> dev_data file: read device data that needs to be migrated from the
>>> current device in real time
>>> migf_data file: read the migration data of the last live migration
>>> from the current driver.
>>> cmd_state: used to get the cmd channel state for the device.
>>>
>>> +----------------+ +--------------+ +---------------+
>>> | migration dev | | src dev | | dst dev |
>>> +-------+--------+ +------+-------+ +-------+-------+
>>> | | |
>>> | +------v-------+ +-------v-------+
>>> | | saving_migf | | resuming_migf |
>>> read | | file | | file |
>>> | +------+-------+ +-------+-------+
>>> | | copy |
>>> | +------------+----------+
>>> | |
>>> +-------v--------+ +-------v--------+
>>> | data buffer | | debug_migf |
>>> +-------+--------+ +-------+--------+
>>> | |
>>> cat | cat |
>>> +-------v--------+ +-------v--------+
>>> | dev_data | | migf_data |
>>> +----------------+ +----------------+
>>>
>>> When accessing debugfs, user can obtain the most recent status data
>>> of the device through the "dev_data" file. It can read recent
>>> complete status data of the device. If the current device is being
>>> migrated, it will wait for it to complete.
>>> The data for the last completed migration function will be stored
>>> in debug_migf. Users can read it via "migf_data".
>>>
>>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>>> Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
>>> ---
>>> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 204 ++++++++++++++++++
>>> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 7 +
>>> 2 files changed, 211 insertions(+)
>>>
>>> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> index a8c53952d82e..0577d4ddfb34 100644
>>> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
>>> @@ -627,15 +627,30 @@ static void hisi_acc_vf_disable_fd(struct hisi_acc_vf_migration_file *migf)
>>> mutex_unlock(&migf->lock);
>>> }
>>>
>>> +static void hisi_acc_debug_migf_copy(struct hisi_acc_vf_core_device *hisi_acc_vdev,
>>> + struct hisi_acc_vf_migration_file *src_migf)
>>> +{
>>> + struct hisi_acc_vf_migration_file *dst_migf = hisi_acc_vdev->debug_migf;
>>> +
>>> + if (!dst_migf)
>>> + return;
>>> +
>>> + 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_fds(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>> {
>>> if (hisi_acc_vdev->resuming_migf) {
>>> + hisi_acc_debug_migf_copy(hisi_acc_vdev, hisi_acc_vdev->resuming_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_debug_migf_copy(hisi_acc_vdev, hisi_acc_vdev->saving_migf);
>>> hisi_acc_vf_disable_fd(hisi_acc_vdev->saving_migf);
>>> fput(hisi_acc_vdev->saving_migf->filp);
>>> hisi_acc_vdev->saving_migf = NULL;
>>> @@ -1294,6 +1309,140 @@ 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_check(struct seq_file *seq, 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;
>>> + int ret;
>>> +
>>> + lockdep_assert_held(&hisi_acc_vdev->open_mutex);
>>> + /*
>>> + * When the device is not opened, the io_base is not mapped.
>>> + * The driver cannot perform device read and write operations.
>>> + */
>>> + if (!hisi_acc_vdev->dev_opened) {
>>> + seq_printf(seq, "device not opened!\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> + ret = qm_wait_dev_not_ready(vf_qm);
>>> + if (ret) {
>>> + seq_printf(seq, "VF device not ready!\n");
>>> + return -EBUSY;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vf_debug_cmd(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_qm *vf_qm = &hisi_acc_vdev->vf_qm;
>>> + u64 value;
>>> + int ret;
>>> +
>>> + mutex_lock(&hisi_acc_vdev->open_mutex);
>>> + ret = hisi_acc_vf_debug_check(seq, vdev);
>>> + if (ret) {
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> + return ret;
>>> + }
>>> +
>>> + value = readl(vf_qm->io_base + QM_MB_CMD_SEND_BASE);
>>> + if (value == QM_MB_CMD_NOT_READY) {
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> + seq_printf(seq, "mailbox cmd channel not ready!\n");
>>> + return -EINVAL;
>>> + }
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> + seq_printf(seq, "mailbox cmd channel ready!\n");
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int hisi_acc_vf_dev_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);
>>> + size_t vf_data_sz = offsetofend(struct acc_vf_data, padding);
>>> + struct acc_vf_data *vf_data = NULL;
>>
>> Nit, this initialization is unnecessary.
>>
>
> OK, delete it in next version.
>
>>> + int ret;
>>> +
>>> + mutex_lock(&hisi_acc_vdev->open_mutex);
>>> + ret = hisi_acc_vf_debug_check(seq, vdev);
>>> + if (ret) {
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> + return ret;
>>> + }
>>> +
>>> + mutex_lock(&hisi_acc_vdev->state_mutex);
>>> + vf_data = kzalloc(sizeof(struct acc_vf_data), GFP_KERNEL);
>>> + if (!vf_data) {
>>> + ret = -ENOMEM;
>>> + goto mutex_release;
>>> + }
>>> +
>>> + vf_data->vf_qm_state = hisi_acc_vdev->vf_qm_state;
>>> + ret = vf_qm_read_data(&hisi_acc_vdev->vf_qm, vf_data);
>>> + if (ret)
>>> + goto migf_err;
>>> +
>>> + seq_hex_dump(seq, "Dev Data:", DUMP_PREFIX_OFFSET, 16, 1,
>>> + (unsigned char *)vf_data,
>>
>> Casting to (const void *) would match the prototype. This line should
>> also wrap to just inside the opening parenthesis of the previous line, 2
>> tabs, 5 spaces.
>>
>
> OK, I will adjust it in the next version.
>
>>> + vf_data_sz, false);
>>> +
>>> + seq_printf(seq,
>>> + "acc device:\n"
>>> + "guest driver load: %u\n"
>>> + "data size: %lu\n",
>>> + hisi_acc_vdev->vf_qm_state,
>>> + sizeof(struct acc_vf_data));
>>
>> Same here and throughout, wrap aligned to the relevant parenthesis.
>>
>
> OK.
>
>> I know you've described vf_qm_state as indicating whether or not the
>> guest driver is loaded, but I still can't figure out how to discern
>> that from the code. It's largely only set based on the return value of
>> qm_wait_dev_not_ready(), which tests QM_VF_STATE, and describes the
>> function as testing if the device is ready. Improved comments would
>> help future reviews.
>>
>
> This QM_VF_STATE register will be written to QM_READY when the acc device
> driver is loaded, and QM_NOT_READY will be written after the device
> driver is unloaded.
>> I will add a comment where vf_qm_state is declared.
>
>> What's the purpose of the "acc device:" prefix?
>>
>
> OK, it can be deleted.
>
>>> +
>>> +migf_err:
>>> + kfree(vf_data);
>>> +mutex_release:
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>>
>> Locks should be released in the reverse order they were acquired.
>>
>
> OK.
>
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static int hisi_acc_vf_migf_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);
>>> + size_t vf_data_sz = offsetofend(struct acc_vf_data, padding);
>>> + struct hisi_acc_vf_migration_file *debug_migf = hisi_acc_vdev->debug_migf;
>>> +
>>> + /* Check whether the live migration operation has been performed */
>>> + if (debug_migf->total_length < QM_MATCH_SIZE) {
>>> + seq_printf(seq, "device not migrated!\n");
>>> + return -EAGAIN;
>>> + }
>>> +
>>> + seq_hex_dump(seq, "Mig Data:", DUMP_PREFIX_OFFSET, 16, 1,
>>> + (unsigned char *)&debug_migf->vf_data,
>>> + vf_data_sz, false);
>>> +
>>> + seq_printf(seq,
>>> + "acc device:\n"
>>> + "guest driver load: %u\n"
>>> + "device opened: %d\n"
>>> + "migrate data length: %lu\n",
>>> + hisi_acc_vdev->vf_qm_state,
>>> + hisi_acc_vdev->dev_opened,
>>> + debug_migf->total_length);
>>
>> This debugfs entry is described as returning the data from the last
>> migration, but vf_qm_state and dev_opened are relative to the current
>> device/guest driver state. Both seem to have no relevance to the data
>> in debug_migf.
>>
>
> The benefit of dev_opened retention is that user can obtain the device status
> during the cat migf_data operation.
>

I will remove dev_opened in the next version.
And hisi_acc_vdev->vf_qm_state is changed to debug_migf->vf_data.vf_qm_state
Keep information about whether the device driver in the Guest OS is loaded
when live migration occurs.

Thanks，
Longfang.

> And vf_qm_state does need to be retained.
> Because adding a driver or not adding a driver to the Guest OS has a great impact
> on the results of live migration, it is a key factor. It has a great impact on
> the success or failure of live migration.
>
> When adding a driver, live migration will read device status data, and data will
> be written back to device after the migration is completed.
> When no driver is added, live migration only executes a process. It does not
> perform data reading and data recovery operations.
>
>>> +
>>> + return 0;
>>> +}
>>> +
>>> 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);
>>> @@ -1305,12 +1454,16 @@ static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
>>> return ret;
>>>
>>> if (core_vdev->mig_ops) {
>>> + mutex_lock(&hisi_acc_vdev->open_mutex);
>>> ret = hisi_acc_vf_qm_init(hisi_acc_vdev);
>>> if (ret) {
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> vfio_pci_core_disable(vdev);
>>> return ret;
>>> }
>>> hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
>>> + hisi_acc_vdev->dev_opened = true;
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> }
>>>
>>> vfio_pci_core_finish_enable(vdev);
>>> @@ -1322,7 +1475,10 @@ static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev)
>>> struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev);
>>> struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
>>>
>>> + mutex_lock(&hisi_acc_vdev->open_mutex);
>>> + hisi_acc_vdev->dev_opened = false;
>>> iounmap(vf_qm->io_base);
>>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>>> vfio_pci_core_close_device(core_vdev);
>>> }
>>>
>>> @@ -1342,6 +1498,7 @@ static int hisi_acc_vfio_pci_migrn_init_dev(struct vfio_device *core_vdev)
>>> hisi_acc_vdev->pf_qm = pf_qm;
>>> hisi_acc_vdev->vf_dev = pdev;
>>> mutex_init(&hisi_acc_vdev->state_mutex);
>>> + mutex_init(&hisi_acc_vdev->open_mutex);
>>>
>>> core_vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_PRE_COPY;
>>> core_vdev->mig_ops = &hisi_acc_vfio_pci_migrn_state_ops;
>>> @@ -1387,6 +1544,50 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
>>> .detach_ioas = vfio_iommufd_physical_detach_ioas,
>>> };
>>>
>>> +static void 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 dentry *vfio_dev_migration = NULL;
>>> + struct dentry *vfio_hisi_acc = NULL;
>>> + struct device *dev = vdev->dev;
>>> + void *migf = NULL;
>>> +
>>> + if (!debugfs_initialized() ||
>>> + !IS_ENABLED(CONFIG_VFIO_DEBUGFS))
>>> + return;
>>> +
>>> + if (vdev->ops != &hisi_acc_vfio_pci_migrn_ops)
>>> + return;
>>> +
>>> + vfio_dev_migration = debugfs_lookup("migration", vdev->debug_root);
>>> + if (!vfio_dev_migration) {
>>> + dev_err(dev, "failed to lookup migration debugfs file!\n");
>>> + return;
>>> + }
>>> +
>>> + migf = kzalloc(sizeof(struct hisi_acc_vf_migration_file), GFP_KERNEL);
>>> + if (!migf)
>>> + return;
>>> + hisi_acc_vdev->debug_migf = migf;
>>> +
>>> + vfio_hisi_acc = debugfs_create_dir("hisi_acc", vfio_dev_migration);
>>> + debugfs_create_devm_seqfile(dev, "dev_data", vfio_hisi_acc,
>>> + hisi_acc_vf_dev_read);
>>> + debugfs_create_devm_seqfile(dev, "migf_data", vfio_hisi_acc,
>>> + hisi_acc_vf_migf_read);
>>> + debugfs_create_devm_seqfile(dev, "cmd_state", vfio_hisi_acc,
>>> + hisi_acc_vf_debug_cmd);
>>> +}
>>> +
>>> +static void hisi_acc_vf_debugfs_exit(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>>> +{
>>> + /* If migrn_ops is not used, debug_migf is NULL */
>>> + if (hisi_acc_vdev->debug_migf) {
>>
>> This test is unnecessary, kfree(NULL) is valid.
>>
>
> OK, It will be deleted. Comments will also be updated.
>
>>> + kfree(hisi_acc_vdev->debug_migf);
>>> + hisi_acc_vdev->debug_migf = NULL;
>>> + }
>>> +}
>>> +
>>> static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>> {
>>> struct hisi_acc_vf_core_device *hisi_acc_vdev;
>>> @@ -1413,6 +1614,8 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device
>>> ret = vfio_pci_core_register_device(&hisi_acc_vdev->core_device);
>>> if (ret)
>>> goto out_put_vdev;
>>> +
>>> + hisi_acc_vfio_debug_init(hisi_acc_vdev);
>>> return 0;
>>>
>>> out_put_vdev:
>>> @@ -1425,6 +1628,7 @@ static void hisi_acc_vfio_pci_remove(struct pci_dev *pdev)
>>> struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev);
>>>
>>> vfio_pci_core_unregister_device(&hisi_acc_vdev->core_device);
>>> + hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
>>> 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 5bab46602fad..2a78ffd060c3 100644
>>> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
>>> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
>>> @@ -32,6 +32,7 @@
>>> #define QM_SQC_VFT_BASE_MASK_V2 GENMASK(15, 0)
>>> #define QM_SQC_VFT_NUM_SHIFT_V2 45
>>> #define QM_SQC_VFT_NUM_MASK_V2 GENMASK(9, 0)
>>> +#define QM_MB_CMD_NOT_READY 0xffffffff
>>>
>>> /* RW regs */
>>> #define QM_REGS_MAX_LEN 7
>>> @@ -99,6 +100,8 @@ struct hisi_acc_vf_migration_file {
>>> struct hisi_acc_vf_core_device {
>>> struct vfio_pci_core_device core_device;
>>> u8 match_done;
>>> + /* To make sure the device is opened */
>>
>> We can infer that from the field name, it would be more useful to
>> comment that io_base is only valid when dev_opened, which is protected
>> by open_mutex.
>>
>
> OK, the comments will be updated according to your instructions.
>
>>> + bool dev_opened;
>>
>> Seems like open_mutex would fit just as well here and have better
>> proximity to the data it protects.
>>
>
> OK, I'm going to move it over here.
>
>>>
>>> /* For migration state */
>>> struct mutex state_mutex;
>>> @@ -111,5 +114,9 @@ struct hisi_acc_vf_core_device {
>>> int vf_id;
>>> struct hisi_acc_vf_migration_file *resuming_migf;
>>> struct hisi_acc_vf_migration_file *saving_migf;
>>> +
>>> + /* To save migration data */
>>
>> Clearly. Describing it as an extra buffer for reporting migration data
>> through debugfs might be more useful. Thanks,
>>
>
> OK, the comments will be updated according to your instructions.
>
> Thanks.
> Longfang.
>
>> Alex
>>
>>> + struct hisi_acc_vf_migration_file *debug_migf;
>>> + struct mutex open_mutex;
>>> };
>>> #endif /* HISI_ACC_VFIO_PCI_H */
>>
>>
>> .
>>
>
> .
>