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Message-ID: <45134ad2-45b3-de1f-c1d5-d077ca0081c2@huawei.com>
Date: Sat, 12 Oct 2024 17:03:26 +0800
From: liulongfang <liulongfang@...wei.com>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>,
"alex.williamson@...hat.com" <alex.williamson@...hat.com>, "jgg@...dia.com"
<jgg@...dia.com>, Jonathan Cameron <jonathan.cameron@...wei.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linuxarm@...neuler.org" <linuxarm@...neuler.org>
Subject: Re: [PATCH v9 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon
migration driver
On 2024/10/11 16:09, Shameerali Kolothum Thodi wrote:
>
>
>> -----Original Message-----
>> From: liulongfang <liulongfang@...wei.com>
>> Sent: Friday, September 13, 2024 10:55 AM
>> To: alex.williamson@...hat.com; jgg@...dia.com; Shameerali Kolothum
>> Thodi <shameerali.kolothum.thodi@...wei.com>; Jonathan Cameron
>> <jonathan.cameron@...wei.com>
>> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
>> linuxarm@...neuler.org; liulongfang <liulongfang@...wei.com>
>> Subject: [PATCH v9 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon
>> migration driver
>>
>> 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>
>> ---
>> .../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..da9f5b9e6c5b 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 +1309,181 @@ 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;
>> + }
>
> Still not very sure this vf_qm ready() check actually helps or not? What guarantee
> is there that the qm will stay Ready after this call? Any read/write afterwards
> will eventually fail if it is not ready later for some reason, right?
> Perhaps helps in early detection and bails out.
>
The purpose here is to intercept invalid debugfs operations.
When VF does not add a driver in Guest OS. The internal data reading and recovery
operations of the live migration operation will be skipped.
The data read is all empty data.
>> + 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;
>> + int ret;
>> +
>> + vf_data = kzalloc(sizeof(struct acc_vf_data), GFP_KERNEL);
>> + if (!vf_data)
>> + return -ENOMEM;\
>
> You could move the allocation after the below checks and to just before
> vf_qm_read_data().
>
OK.
>> +
>> + mutex_lock(&hisi_acc_vdev->open_mutex);
>> + ret = hisi_acc_vf_debug_check(seq, vdev);
>> + if (ret) {
>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>> + goto migf_err;
>> + }
>> +
>> + mutex_lock(&hisi_acc_vdev->state_mutex);
>> + 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->open_mutex);
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>
> I think it is better to unlock in the reverse order. Also probably you can move
> the unlocks to a goto area.
>
My consideration is to release the mutex before outputting the log.
it can be optimized.
>> + goto migf_err;
>> + }
>> +
>> + mutex_unlock(&hisi_acc_vdev->open_mutex);
>> + mutex_unlock(&hisi_acc_vdev->state_mutex);
>
> Same as above.
OK.
>
>> + 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"
>> + "guest driver load: %u\n"
>> + "data size: %lu\n",
>> + hisi_acc_vdev->vf_qm_state,
>> + sizeof(struct acc_vf_data));
>> +
>> +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, "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);
>> +
>> + return 0;
>> +}
>> +
>> +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;
>> +
>> + 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 (hisi_acc_vdev->debug_migf) {
>> + kfree(hisi_acc_vdev->debug_migf);
>> + 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);
>> @@ -1305,12 +1495,16 @@ 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 +1516,10 @@ 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 +1539,7 @@ 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;
>> @@ -1413,6 +1611,9 @@ 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);
>
> I think there was a comment earlier on this. Still not sure why it is not possible to
> move ops == &hisi_acc_vfio_pci_migrn_ops check inside hisi_acc_vfio_debug_init().
>
The variable hisi_acc_vfio_pci_migrn_ops is declared after the function hisi_acc_vfio_debug_init.
If placed inside the function, a compilation error will occur.
>> return 0;
>>
>> out_put_vdev:
>> @@ -1423,8 +1624,11 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev
>> *pdev, const struct pci_device
>> static void hisi_acc_vfio_pci_remove(struct pci_dev *pdev)
>> {
>> struct hisi_acc_vf_core_device *hisi_acc_vdev =
>> hisi_acc_drvdata(pdev);
>> + struct vfio_device *vdev = &hisi_acc_vdev->core_device.vdev;
>>
>> vfio_pci_core_unregister_device(&hisi_acc_vdev->core_device);
>> + if (vdev->ops == &hisi_acc_vfio_pci_migrn_ops)
>> + hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
>
> Do we need to do vdev->ops == &hisi_acc_vfio_pci_migrn_ops check here?
>
> Since we are checking
> hisi_acc_vdev->debug_migf inside the exit function, which I think is only
> set when the ops == migrn_ops. Right?
>
"vdev->ops == &hisi_acc_vfio_pci_migrn_ops" is added here to maintain symmetry
with the code processing in the probe.
I added it also because of another reviewer’s suggestion.
Thanks.
Longfang.
> Thanks,
> Shameer
>
> .
>
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