linux-kernel - Re: [PATCH v5 3/3] crypto: hisilicon/qm - defining the device isolation strategy

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Date:   Fri, 8 Jul 2022 09:35:14 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Kai Ye <yekai13@...wei.com>
Cc:     herbert@...dor.apana.org.au, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, wangzhou1@...ilicon.com
Subject: Re: [PATCH v5 3/3] crypto: hisilicon/qm - defining the device
 isolation strategy

On Fri, Jul 08, 2022 at 03:08:20PM +0800, Kai Ye wrote:
> Define the device isolation strategy by the device driver. The
> user configures a frequency value by uacce interface. If the
> slot reset frequency exceeds the value of setting for a certain
> period of time, the device will not be available in user space.
> The time window is one hour. The VF device use the PF device
> isolation strategy. All the hardware errors are processed by PF
> driver. This solution can be used for other drivers.
> 
> Signed-off-by: Kai Ye <yekai13@...wei.com>
> ---
>  drivers/crypto/hisilicon/qm.c | 163 +++++++++++++++++++++++++++++++---
>  include/linux/hisi_acc_qm.h   |   9 ++
>  2 files changed, 160 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/crypto/hisilicon/qm.c b/drivers/crypto/hisilicon/qm.c
> index ad83c194d664..8eb3b790a655 100644
> --- a/drivers/crypto/hisilicon/qm.c
> +++ b/drivers/crypto/hisilicon/qm.c
> @@ -417,6 +417,16 @@ struct hisi_qm_resource {
>  	struct list_head list;
>  };
>  
> +/**
> + * struct qm_hw_err - Structure describing the device errors
> + * @list: hardware error list
> + * @timestamp: timestamp when the error occurred
> + */
> +struct qm_hw_err {
> +	struct list_head list;
> +	unsigned long long timestamp;
> +};
> +
>  struct hisi_qm_hw_ops {
>  	int (*get_vft)(struct hisi_qm *qm, u32 *base, u32 *number);
>  	void (*qm_db)(struct hisi_qm *qm, u16 qn,
> @@ -3410,6 +3420,111 @@ static long hisi_qm_uacce_ioctl(struct uacce_queue *q, unsigned int cmd,
>  	return 0;
>  }
>  
> +/**
> + * qm_hw_err_isolate() - Try to isolate the uacce device with its VFs
> + * according to user's configuration of isolation strategy. Warning: this
> + * API should be called while there the users on this device are suspended
> + * by slot resetting preparation of PCI AER.
> + * @qm: the uacce device
> + */
> +static int qm_hw_err_isolate(struct hisi_qm *qm)
> +{
> +	struct qm_hw_err *err, *tmp, *hw_err;
> +	struct qm_err_isolate *isolate;
> +	u32 count = 0;
> +
> +	isolate = &qm->isolate_data;
> +
> +#define SECONDS_PER_HOUR	3600
> +
> +	/* All the hw errs are processed by PF driver */
> +	if (qm->uacce->is_vf || isolate->is_isolate ||
> +	    !isolate->hw_err_isolate_hz)
> +		return 0;
> +
> +	hw_err = kzalloc(sizeof(*hw_err), GFP_ATOMIC);

Why atomic?  What lock is held here?

> +	if (!hw_err)
> +		return -ENOMEM;
> +
> +	mutex_lock(&isolate->isolate_lock);
> +	hw_err->timestamp = jiffies;
> +	list_for_each_entry_safe(err, tmp, &isolate->uacce_hw_errs, list) {
> +		if ((hw_err->timestamp - err->timestamp) / HZ >
> +		    SECONDS_PER_HOUR) {

No possiblity of wrapping the timestamp?

> +			list_del(&err->list);
> +			kfree(err);
> +		} else {
> +			count++;
> +		}
> +	}
> +	list_add(&hw_err->list, &isolate->uacce_hw_errs);
> +	mutex_unlock(&isolate->isolate_lock);
> +
> +	if (count >= isolate->hw_err_isolate_hz)
> +		isolate->is_isolate = true;
> +
> +	return 0;
> +}
> +
> +static void qm_hw_err_destroy(struct hisi_qm *qm)
> +{
> +	struct qm_hw_err *err, *tmp;
> +
> +	mutex_lock(&qm->isolate_data.isolate_lock);
> +	list_for_each_entry_safe(err, tmp, &qm->isolate_data.uacce_hw_errs, list) {
> +		list_del(&err->list);
> +		kfree(err);
> +	}
> +	mutex_unlock(&qm->isolate_data.isolate_lock);
> +}
> +
> +static enum uacce_dev_state hisi_qm_get_isolate_state(struct uacce_device *uacce)
> +{
> +	struct hisi_qm *qm = uacce->priv;
> +	struct hisi_qm *pf_qm;
> +
> +	if (uacce->is_vf)
> +		pf_qm = pci_get_drvdata(pci_physfn(qm->pdev));
> +	else
> +		pf_qm = qm;
> +
> +	return pf_qm->isolate_data.is_isolate ?
> +			UACCE_DEV_ISOLATE : UACCE_DEV_NORMAL;
> +}
> +
> +static int hisi_qm_isolate_strategy_write(struct uacce_device *uacce,
> +					  u32 freq)
> +{
> +	struct hisi_qm *qm = uacce->priv;
> +
> +	/* Must be set by PF */
> +	if (uacce->is_vf)
> +		return -EINVAL;

But the value passed to you is not invalid, something else went wrong.
Are you sure this is the correct error?

> +
> +	if (qm->isolate_data.is_isolate)
> +		return -EINVAL;

Same here, why is this correct?

> +
> +	qm->isolate_data.hw_err_isolate_hz = freq;

No validation of the value passed to you?  It can be anything?

> +
> +	/* After the policy is updated, need to reset the hardware err list */
> +	qm_hw_err_destroy(qm);

No error checking?

thanks,

greg k-h