Message-ID: <20241105112108.14255a9e.alex.williamson@redhat.com>
Date: Tue, 5 Nov 2024 11:21:08 -0700
From: Alex Williamson <alex.williamson@...hat.com>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
Cc: liulongfang <liulongfang@...wei.com>, "jgg@...dia.com" <jgg@...dia.com>,
 "Jonathan Cameron" <jonathan.cameron@...wei.com>, "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 v12 3/4] hisi_acc_vfio_pci: register debugfs for
 hisilicon migration driver

On Tue, 5 Nov 2024 08:55:51 +0000
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com> wrote:

> > -----Original Message-----
> > From: liulongfang <liulongfang@...wei.com>
> > Sent: Tuesday, November 5, 2024 3:53 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 v12 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon
> > migration driver  
> 
> Hi,
> 
> Few minor comments below. Please don't re-spin just for these yet.
> Please wait for others to review as well.
> 
> Thanks,
> Shameer
> 
> > diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> > b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> > index a8c53952d82e..7728c9745b9d 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)  
> 
> Alignment should match open parenthesis here.

I might also shorten the first line to 80 chars by putting "static" or
"static void" on a line by itself, but we're getting into personal
preference at that point and this driver already has lines exceeding 80
columns.

> > +{
> > +	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));  
> 
> Here too, alignment not correct. It is better to run,
> ./scripts/checkpatch --strict on these patches if you haven't done already.

Yup.  Only those two were missed as far as I see, but checkpatch does
warn several places where we should use seq_puts() rather than
seq_printf() for cases of printing a constant format without additional
arguments.  For example "device not opened!\n" is the first one below
but there are others.

> > +}
> > +
> >  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 +1309,129 @@ 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;
> > +	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,
> > +		     (const void *)vf_data, vf_data_sz, false);
> > +
> > +	seq_printf(seq,
> > +		   "guest driver load: %u\n"
> > +		   "data size: %lu\n",
> > +		   hisi_acc_vdev->vf_qm_state,
> > +		   sizeof(struct acc_vf_data));  
> 
> There was a suggestion to add a comment here to describe vf_qm_state better.
> May be something like,
> 
> vf_qm_state here indicates whether the Guest has loaded the driver for the ACC VF
> device or not.

I think the comment ended up at the declaration of vf_qm_state in the
header file:

> @@ -107,9 +114,17 @@ struct hisi_acc_vf_core_device {
>  	struct pci_dev *vf_dev;
>  	struct hisi_qm *pf_qm;
>  	struct hisi_qm vf_qm;
> +	/*
> +	 * Record whether a driver is added to the acc device in Guest OS.
> +	 * The value of QM_VF_STATE is set by the acc device driver.
> +	 * The migration driver queries through the QM_VF_STATE register.
> +	 */
>  	u32 vf_qm_state;
>  	int vf_id;
>  	struct hisi_acc_vf_migration_file *resuming_migf;
>  	struct hisi_acc_vf_migration_file *saving_migf;
> +
> +	/* An extra buffer for reporting migration data via debugfs */
> +	struct hisi_acc_vf_migration_file *debug_migf;
>  };
>  #endif /* HISI_ACC_VFIO_PCI_H */

Is that satisfactory?

> > +
> > +migf_err:
> > +	kfree(vf_data);
> > +mutex_release:
> > +	mutex_unlock(&hisi_acc_vdev->state_mutex);
> > +	mutex_unlock(&hisi_acc_vdev->open_mutex);
> > +
> > +	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,
> > +		     (const void *)&debug_migf->vf_data, vf_data_sz, false);
> > +	seq_printf(seq, "migrate data length: %lu\n", debug_migf-  
> > >total_length);  
> > +
> > +	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 +1443,16 @@ 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 +1464,10 @@ 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 +1487,7 @@ 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 +1533,48 @@ 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);

checkpatch --strict also advises this could be written as:

	migf = kzalloc(sizeof(*migf), GFP_KERNEL);

There's another one above with acc_vf_data.  I'd consider these
optional, but I think it is good practice and is more consistent with
existing allocations in this file.

> > +	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, kfree(NULL) is valid */  
> 
> The above comment is not required. Please remove.

I don't have a problem with it, but I'll let the two of you decide as
co-owners of the file.  Thanks,

Alex


> > +	kfree(hisi_acc_vdev->debug_migf);
> > +	hisi_acc_vdev->debug_migf = NULL;
> > +}
> > +  
> 

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