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Message-ID: <df5129f8-e9c2-b1c0-e2de-9211738d88c4@huawei.com>
Date: Mon, 4 Nov 2024 15:54:13 +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>, <kvm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linuxarm@...neuler.org>
Subject: Re: [PATCH v11 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon
migration driver
On 2024/11/1 6:04, Alex Williamson wrote:
> On Fri, 25 Oct 2024 17:01:42 +0800
> Longfang Liu <liulongfang@...wei.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@...wei.com>
>> Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.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.
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 */
>
>
> .
>
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