On 2024/8/27 5:06, Alex Williamson wrote:
> On Tue, 6 Aug 2024 20:29:27 +0800
> Longfang Liu <liulongfang@xxxxxxxxxx> 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@xxxxxxxxxx>
>> ---
>> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 209 ++++++++++++++++++
>> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 6 +
>> 2 files changed, 215 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..379657904f86 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 +1309,191 @@ 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->state_mutex);
>> + if (!vdev->mig_ops) {
>> + seq_printf(seq, "%s\n", "device does not support live migration!\n");
>> + return -EINVAL;
>> + }
>
> I don't think it's possible for this to be called with this condition,
> the debugfs files are only registered when this exists.
>
> Also, we don't need %s for a fixed string, nor do we need multiple new
> lines. Please fix throughout.
>
>> +
>> + /*
>> + * 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, "%s\n", "device not opened!\n");
>> + return -EINVAL;
>> + }
>> +
>> + ret = qm_wait_dev_not_ready(vf_qm);
>> + if (ret) {
>> + seq_printf(seq, "%s\n", "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->state_mutex);
>> + ret = hisi_acc_vf_debug_check(seq, vdev);
>> + if (ret) {
>> + mutex_unlock(&hisi_acc_vdev->state_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->state_mutex);
>> + seq_printf(seq, "mailbox cmd channel not ready!\n");
>> + return -EINVAL;
>> + }
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>> + seq_printf(seq, "mailbox cmd channel ready!\n");
>
> This debugfs entry seems pretty pointless to me. Also we polled for
> the device to be ready in debug_check, so if the channel is not ready
> aren't we more likely to see any error (without a seq_printf) in the
> first error branch?
>
>> +
>> + 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;
>> + int ret;
>> +
>> + vf_data = kzalloc(sizeof(struct acc_vf_data), GFP_KERNEL);
>> + if (!vf_data)
>> + return -ENOMEM;
>> +
>> + mutex_lock(&hisi_acc_vdev->state_mutex);
>> + ret = hisi_acc_vf_debug_check(seq, vdev);
>> + if (ret) {
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>> + goto migf_err;
>> + }
>> +
>> + 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) {
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>> + goto migf_err;
>> + }
>> +
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>> +
>> + seq_hex_dump(seq, "Dev Data:", DUMP_PREFIX_OFFSET, 16, 1,
>> + (unsigned char *)vf_data,
>> + vf_data_sz, false);
>> +
>> + seq_printf(seq,
>> + "acc device:\n"
>> + "device ready: %u\n"
>> + "device opened: %d\n"
>> + "data size: %lu\n",
>> + hisi_acc_vdev->vf_qm_state,
>> + hisi_acc_vdev->dev_opened,
>> + sizeof(struct acc_vf_data));
>
> This function called hisi_acc_vf_debug_check() which requires the
> device to be opened, therefore except for the race where the unlock
> allowed the device to close, what is the purpose of printing the opened
> state here? We can also tell from the hex dump the size of the data,
> so why is that value printed here? vf_qm_state appears to be a state
> value rather than a bool, so labeling it as "ready" doesn't make much
> sense. The arbitrary white space also doesn't make much sense.
>
>> +
>> +migf_err:
>> + kfree(vf_data);
>> +
>> + 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, "%s\n", "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);
>
> Why doesn't this stop at total_length?
>
>> +
>> + seq_printf(seq,
>> + "acc device:\n"
>> + "device ready: %u\n"
>> + "device opened: %d\n"
>> + "data size: %lu\n",
>> + hisi_acc_vdev->vf_qm_state,
>> + hisi_acc_vdev->dev_opened,
>> + debug_migf->total_length);
>
> Again, "ready" seems more like a "state" value, here opened could be
> false, but why do we care(?), size could be inferred from the hex dump,
> and white spaces are arbitrary.
>
>> +
>> + 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 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 0;
>> +
>> + migf = kzalloc(sizeof(struct hisi_acc_vf_migration_file), GFP_KERNEL);
>> + if (!migf)
>> + return -ENOMEM;
>> + hisi_acc_vdev->debug_migf = migf;
>> +
>> + vfio_dev_migration = debugfs_lookup("migration", vdev->debug_root);
>
> Test this before anything is allocated or assigned.
>
>> + if (!vfio_dev_migration) {
>> + kfree(migf);
>> + hisi_acc_vdev->debug_migf = NULL;
>> + dev_err(dev, "failed to lookup migration debugfs file!\n");
>> + return -ENODEV;
>> + }
>> +
>> + 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);
>> +
>> + return 0;
>> +}
>
> Why does this function return an int when the only caller ignores the
> return value?
>
Okay, I can change this function to void return type.
>> +
>> +static void hisi_acc_vf_debugfs_exit(struct hisi_acc_vf_core_device *hisi_acc_vdev)
>> +{
>> + if (!debugfs_initialized() ||
>> + !IS_ENABLED(CONFIG_VFIO_DEBUGFS))
>> + return;
>
> Do we really need to test these on the exit path? debug_migf would not
> be allocated.
>
Yes, redundant checks can be deleted here.
>> +
>> + if (hisi_acc_vdev->debug_migf)
>> + kfree(hisi_acc_vdev->debug_migf);
>
> I suppose this is not set NULL because this is only called in the
> device remove path.
OK, I can add a line:
hisi_acc_vdev->debug_migf = NULL;
>
>> +}
>> +
>> 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);
>> @@ -1311,9 +1511,11 @@ static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
>> return ret;
>> }
>> hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
>> + hisi_acc_vdev->dev_opened = true;
>> }
>>
>> vfio_pci_core_finish_enable(vdev);
>> +
>> return 0;
>> }
>>
>> @@ -1322,7 +1524,10 @@ 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->state_mutex);
>> + hisi_acc_vdev->dev_opened = false;
>> iounmap(vf_qm->io_base);
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>
> Co-opting the state_mutex to protect dev_opened is rather sketchy.
>
So do we need to reconsider creating a new mmap_mutex here?
>> vfio_pci_core_close_device(core_vdev);
>> }
>>
>> @@ -1413,6 +1618,9 @@ 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;
>> +
>> + if (ops == &hisi_acc_vfio_pci_migrn_ops)
>> + hisi_acc_vfio_debug_init(hisi_acc_vdev);
>
> Call this unconditionally and test hisi_acc_vdev->mig_ops in the
> debug_init function. That way init and exit are symmetric.
>
OK, here is the processing code in exit, like this:
if (vdev->ops == &hisi_acc_vfio_pci_migrn_ops)
hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
>> return 0;
>>
>> out_put_vdev:
>> @@ -1425,6 +1633,7 @@ 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..f86f3b88b09e 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
>> @@ -111,5 +112,10 @@ 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 make sure the device is opened */
>> + bool dev_opened;
>> + /* To save migration data */
>> + struct hisi_acc_vf_migration_file *debug_migf;
>
> Poor structure packing.
>
OK, I will adjust the order in the next version.
Thanks.
Longfang.
>> };
>> #endif /* HISI_ACC_VFIO_PCI_H */
>
>
> .
>
