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Re: [PATCH v2] vfio/pci: Support error recovery

Started by"Michael S. Tsirkin" <mst@redhat.com>
First post2017-01-10 00:10 +0100
Last post2017-01-12 17:30 +0100
Articles 5 — 2 participants

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  Re: [PATCH v2] vfio/pci: Support error recovery "Michael S. Tsirkin" <mst@redhat.com> - 2017-01-10 00:10 +0100
    Re: [PATCH v2] vfio/pci: Support error recovery Cao jin <caoj.fnst@cn.fujitsu.com> - 2017-01-10 12:50 +0100
      Re: [PATCH v2] vfio/pci: Support error recovery "Michael S. Tsirkin" <mst@redhat.com> - 2017-01-10 16:20 +0100
        Re: [PATCH v2] vfio/pci: Support error recovery Cao jin <caoj.fnst@cn.fujitsu.com> - 2017-01-11 02:50 +0100
          Re: [PATCH v2] vfio/pci: Support error recovery "Michael S. Tsirkin" <mst@redhat.com> - 2017-01-12 17:30 +0100

#1554779 — Re: [PATCH v2] vfio/pci: Support error recovery

From"Michael S. Tsirkin" <mst@redhat.com>
Date2017-01-10 00:10 +0100
SubjectRe: [PATCH v2] vfio/pci: Support error recovery
Message-ID<sXReF-1Tw-3@gated-at.bofh.it>
On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote:
> Support serious device error recovery

serious?

> 
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> ---
>  drivers/vfio/pci/vfio_pci.c         | 70 +++++++++++++++++++++++++++++++++++--
>  drivers/vfio/pci/vfio_pci_private.h |  2 ++
>  2 files changed, 70 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 712a849..752af20 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data,
>  {
>  	struct vfio_pci_device *vdev = device_data;
>  	unsigned long minsz;
> +	int ret;
> +
> +	if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
> +	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
> +		ret = wait_for_completion_interruptible(
> +			&vdev->aer_completion);

don't split it like that.

> +		if (ret)
> +			return ret;
> +	}
>  
>  	if (cmd == VFIO_DEVICE_GET_INFO) {
>  		struct vfio_device_info info;
> @@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
>  {
>  	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
>  	struct vfio_pci_device *vdev = device_data;
> +	int ret;
> +
> +	/* block all kinds of access during host recovery */
> +	if (vdev->aer_recovering) {
> +		ret = wait_for_completion_interruptible(
> +			&vdev->aer_completion);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
>  		return -EINVAL;
> @@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	vdev->irq_type = VFIO_PCI_NUM_IRQS;
>  	mutex_init(&vdev->igate);
>  	spin_lock_init(&vdev->irqlock);
> +	init_completion(&vdev->aer_completion);
>  
>  	ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
>  	if (ret) {
> @@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>  {
>  	struct vfio_pci_device *vdev;
>  	struct vfio_device *device;
> +	u32 uncor_status;
> +	unsigned int aer_cap_offset;
> +	int ret;
>  
>  	device = vfio_device_get_from_dev(&pdev->dev);
>  	if (device == NULL)
> @@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>  		return PCI_ERS_RESULT_DISCONNECT;
>  	}
>  
> +	/*
> +	 * get device's uncorrectable error status as soon as possible,

should be "Get".

> +	 * and signal it to user space. The later we read it, the possibility
> +	 * the register value is mangled grows.
> +	 */
> +	aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR);
> +	ret = pci_read_config_dword(vdev->pdev, aer_cap_offset +
> +                                    PCI_ERR_UNCOR_STATUS, &uncor_status);
> +        if (ret)
> +                return PCI_ERS_RESULT_DISCONNECT;
> +
> +	pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed

Pls drop this.

>  	mutex_lock(&vdev->igate);
>  
> -	if (vdev->err_trigger)
> -		eventfd_signal(vdev->err_trigger, 1);
> +	vdev->aer_recovering = true;
> +	reinit_completion(&vdev->aer_completion);
> +
> +	if (vdev->err_trigger && uncor_status) {
> +		pr_info("device %d signal uncor status 0x%x to user",
> +			pdev->devfn, uncor_status);
> +		/* signal uncorrectable error status to user space */
> +		eventfd_signal(vdev->err_trigger, uncor_status);
> +        }
>  
>  	mutex_unlock(&vdev->igate);
>  
> @@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>  	return PCI_ERS_RESULT_CAN_RECOVER;
>  }
>  
> +static void vfio_pci_aer_resume(struct pci_dev *pdev)
> +{
> +	struct vfio_pci_device *vdev;
> +	struct vfio_device *device;
> +
> +	device = vfio_device_get_from_dev(&pdev->dev);
> +	if (device == NULL)
> +		return;
> +
> +	vdev = vfio_device_data(device);
> +	if (vdev == NULL) {
> +		vfio_device_put(device);
> +		return;
> +	}
> +
> +	mutex_lock(&vdev->igate);
> +	vdev->aer_recovering = false;
> +	mutex_unlock(&vdev->igate);
> +
> +	complete_all(&vdev->aer_completion);
> +
> +	vfio_device_put(device);
> +}
> +
>  static const struct pci_error_handlers vfio_err_handlers = {
>  	.error_detected = vfio_pci_aer_err_detected,
> +	.resume         = vfio_pci_aer_resume,
>  };
>  
>  static struct pci_driver vfio_pci_driver = {
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index 8a7d546..ba8471f 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -83,6 +83,8 @@ struct vfio_pci_device {
>  	bool			bardirty;
>  	bool			has_vga;
>  	bool			needs_reset;
> +	bool			aer_recovering;
> +	struct completion	aer_completion;
>  	struct pci_saved_state	*pci_saved_state;
>  	int			refcnt;
>  	struct eventfd_ctx	*err_trigger;
> -- 
> 1.8.3.1
> 
> 

How about some explanation about what is going on here?  All these
changes seem racy since any number of errors can trigger at any time.

-- 
MST

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#1555188

FromCao jin <caoj.fnst@cn.fujitsu.com>
Date2017-01-10 12:50 +0100
Message-ID<sY36a-N3-23@gated-at.bofh.it>
In reply to#1554779

On 01/10/2017 07:04 AM, Michael S. Tsirkin wrote:
> On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote:
>> Support serious device error recovery
> 
> serious?
>

Sorry for my poor vocabulary if it confuses people. I wanted to express
the meaning that: vfio-pci actually cannot do a real recovery for device
even if it provides the callbacks, it relies on the user to do a
effective(or word "serious"?) recovery.

Welcome the amendment on the commit log.

-- 
Sincerely,
Cao jin

>>
>> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
>> ---
>>  drivers/vfio/pci/vfio_pci.c         | 70 +++++++++++++++++++++++++++++++++++--
>>  drivers/vfio/pci/vfio_pci_private.h |  2 ++
>>  2 files changed, 70 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>> index 712a849..752af20 100644
>> --- a/drivers/vfio/pci/vfio_pci.c
>> +++ b/drivers/vfio/pci/vfio_pci.c
>> @@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data,
>>  {
>>  	struct vfio_pci_device *vdev = device_data;
>>  	unsigned long minsz;
>> +	int ret;
>> +
>> +	if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
>> +	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
>> +		ret = wait_for_completion_interruptible(
>> +			&vdev->aer_completion);
> 
> don't split it like that.
> 
>> +		if (ret)
>> +			return ret;
>> +	}
>>  
>>  	if (cmd == VFIO_DEVICE_GET_INFO) {
>>  		struct vfio_device_info info;
>> @@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
>>  {
>>  	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
>>  	struct vfio_pci_device *vdev = device_data;
>> +	int ret;
>> +
>> +	/* block all kinds of access during host recovery */
>> +	if (vdev->aer_recovering) {
>> +		ret = wait_for_completion_interruptible(
>> +			&vdev->aer_completion);
>> +		if (ret)
>> +			return ret;
>> +	}
>>  
>>  	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
>>  		return -EINVAL;
>> @@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>  	vdev->irq_type = VFIO_PCI_NUM_IRQS;
>>  	mutex_init(&vdev->igate);
>>  	spin_lock_init(&vdev->irqlock);
>> +	init_completion(&vdev->aer_completion);
>>  
>>  	ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
>>  	if (ret) {
>> @@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>  {
>>  	struct vfio_pci_device *vdev;
>>  	struct vfio_device *device;
>> +	u32 uncor_status;
>> +	unsigned int aer_cap_offset;
>> +	int ret;
>>  
>>  	device = vfio_device_get_from_dev(&pdev->dev);
>>  	if (device == NULL)
>> @@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>  		return PCI_ERS_RESULT_DISCONNECT;
>>  	}
>>  
>> +	/*
>> +	 * get device's uncorrectable error status as soon as possible,
> 
> should be "Get".
> 
>> +	 * and signal it to user space. The later we read it, the possibility
>> +	 * the register value is mangled grows.
>> +	 */
>> +	aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR);
>> +	ret = pci_read_config_dword(vdev->pdev, aer_cap_offset +
>> +                                    PCI_ERR_UNCOR_STATUS, &uncor_status);
>> +        if (ret)
>> +                return PCI_ERS_RESULT_DISCONNECT;
>> +
>> +	pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed
> 
> Pls drop this.
> 
>>  	mutex_lock(&vdev->igate);
>>  
>> -	if (vdev->err_trigger)
>> -		eventfd_signal(vdev->err_trigger, 1);
>> +	vdev->aer_recovering = true;
>> +	reinit_completion(&vdev->aer_completion);
>> +
>> +	if (vdev->err_trigger && uncor_status) {
>> +		pr_info("device %d signal uncor status 0x%x to user",
>> +			pdev->devfn, uncor_status);
>> +		/* signal uncorrectable error status to user space */
>> +		eventfd_signal(vdev->err_trigger, uncor_status);
>> +        }
>>  
>>  	mutex_unlock(&vdev->igate);
>>  
>> @@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>  	return PCI_ERS_RESULT_CAN_RECOVER;
>>  }
>>  
>> +static void vfio_pci_aer_resume(struct pci_dev *pdev)
>> +{
>> +	struct vfio_pci_device *vdev;
>> +	struct vfio_device *device;
>> +
>> +	device = vfio_device_get_from_dev(&pdev->dev);
>> +	if (device == NULL)
>> +		return;
>> +
>> +	vdev = vfio_device_data(device);
>> +	if (vdev == NULL) {
>> +		vfio_device_put(device);
>> +		return;
>> +	}
>> +
>> +	mutex_lock(&vdev->igate);
>> +	vdev->aer_recovering = false;
>> +	mutex_unlock(&vdev->igate);
>> +
>> +	complete_all(&vdev->aer_completion);
>> +
>> +	vfio_device_put(device);
>> +}
>> +
>>  static const struct pci_error_handlers vfio_err_handlers = {
>>  	.error_detected = vfio_pci_aer_err_detected,
>> +	.resume         = vfio_pci_aer_resume,
>>  };
>>  
>>  static struct pci_driver vfio_pci_driver = {
>> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
>> index 8a7d546..ba8471f 100644
>> --- a/drivers/vfio/pci/vfio_pci_private.h
>> +++ b/drivers/vfio/pci/vfio_pci_private.h
>> @@ -83,6 +83,8 @@ struct vfio_pci_device {
>>  	bool			bardirty;
>>  	bool			has_vga;
>>  	bool			needs_reset;
>> +	bool			aer_recovering;
>> +	struct completion	aer_completion;
>>  	struct pci_saved_state	*pci_saved_state;
>>  	int			refcnt;
>>  	struct eventfd_ctx	*err_trigger;
>> -- 
>> 1.8.3.1
>>
>>
> 
> How about some explanation about what is going on here?  All these
> changes seem racy since any number of errors can trigger at any time.
>

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#1555585

From"Michael S. Tsirkin" <mst@redhat.com>
Date2017-01-10 16:20 +0100
Message-ID<sY6nn-2ZC-13@gated-at.bofh.it>
In reply to#1555188
On Tue, Jan 10, 2017 at 07:46:17PM +0800, Cao jin wrote:
> 
> 
> On 01/10/2017 07:04 AM, Michael S. Tsirkin wrote:
> > On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote:
> >> Support serious device error recovery
> > 
> > serious?
> >
> 
> Sorry for my poor vocabulary if it confuses people. I wanted to express
> the meaning that: vfio-pci actually cannot do a real recovery for device
> even if it provides the callbacks, it relies on the user to do a
> effective(or word "serious"?) recovery.
> 
> Welcome the amendment on the commit log.

It's up to Alex, maybe he's able to figure it all out from
code, but the rest of us could benefit from a description
of what the patch does from userspace point of view.

Also, is it a pre-requisite of the userspace patches you posted?

> -- 
> Sincerely,
> Cao jin
> 
> >>
> >> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> >> ---
> >>  drivers/vfio/pci/vfio_pci.c         | 70 +++++++++++++++++++++++++++++++++++--
> >>  drivers/vfio/pci/vfio_pci_private.h |  2 ++
> >>  2 files changed, 70 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> >> index 712a849..752af20 100644
> >> --- a/drivers/vfio/pci/vfio_pci.c
> >> +++ b/drivers/vfio/pci/vfio_pci.c
> >> @@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data,
> >>  {
> >>  	struct vfio_pci_device *vdev = device_data;
> >>  	unsigned long minsz;
> >> +	int ret;
> >> +
> >> +	if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
> >> +	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
> >> +		ret = wait_for_completion_interruptible(
> >> +			&vdev->aer_completion);
> > 
> > don't split it like that.
> > 
> >> +		if (ret)
> >> +			return ret;
> >> +	}
> >>  
> >>  	if (cmd == VFIO_DEVICE_GET_INFO) {
> >>  		struct vfio_device_info info;
> >> @@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
> >>  {
> >>  	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
> >>  	struct vfio_pci_device *vdev = device_data;
> >> +	int ret;
> >> +
> >> +	/* block all kinds of access during host recovery */
> >> +	if (vdev->aer_recovering) {
> >> +		ret = wait_for_completion_interruptible(
> >> +			&vdev->aer_completion);
> >> +		if (ret)
> >> +			return ret;
> >> +	}
> >>  
> >>  	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
> >>  		return -EINVAL;
> >> @@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >>  	vdev->irq_type = VFIO_PCI_NUM_IRQS;
> >>  	mutex_init(&vdev->igate);
> >>  	spin_lock_init(&vdev->irqlock);
> >> +	init_completion(&vdev->aer_completion);
> >>  
> >>  	ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
> >>  	if (ret) {
> >> @@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
> >>  {
> >>  	struct vfio_pci_device *vdev;
> >>  	struct vfio_device *device;
> >> +	u32 uncor_status;
> >> +	unsigned int aer_cap_offset;
> >> +	int ret;
> >>  
> >>  	device = vfio_device_get_from_dev(&pdev->dev);
> >>  	if (device == NULL)
> >> @@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
> >>  		return PCI_ERS_RESULT_DISCONNECT;
> >>  	}
> >>  
> >> +	/*
> >> +	 * get device's uncorrectable error status as soon as possible,
> > 
> > should be "Get".
> > 
> >> +	 * and signal it to user space. The later we read it, the possibility
> >> +	 * the register value is mangled grows.
> >> +	 */
> >> +	aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR);
> >> +	ret = pci_read_config_dword(vdev->pdev, aer_cap_offset +
> >> +                                    PCI_ERR_UNCOR_STATUS, &uncor_status);
> >> +        if (ret)
> >> +                return PCI_ERS_RESULT_DISCONNECT;
> >> +
> >> +	pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed
> > 
> > Pls drop this.
> > 
> >>  	mutex_lock(&vdev->igate);
> >>  
> >> -	if (vdev->err_trigger)
> >> -		eventfd_signal(vdev->err_trigger, 1);
> >> +	vdev->aer_recovering = true;
> >> +	reinit_completion(&vdev->aer_completion);
> >> +
> >> +	if (vdev->err_trigger && uncor_status) {
> >> +		pr_info("device %d signal uncor status 0x%x to user",
> >> +			pdev->devfn, uncor_status);
> >> +		/* signal uncorrectable error status to user space */
> >> +		eventfd_signal(vdev->err_trigger, uncor_status);
> >> +        }
> >>  
> >>  	mutex_unlock(&vdev->igate);
> >>  
> >> @@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
> >>  	return PCI_ERS_RESULT_CAN_RECOVER;
> >>  }
> >>  
> >> +static void vfio_pci_aer_resume(struct pci_dev *pdev)
> >> +{
> >> +	struct vfio_pci_device *vdev;
> >> +	struct vfio_device *device;
> >> +
> >> +	device = vfio_device_get_from_dev(&pdev->dev);
> >> +	if (device == NULL)
> >> +		return;
> >> +
> >> +	vdev = vfio_device_data(device);
> >> +	if (vdev == NULL) {
> >> +		vfio_device_put(device);
> >> +		return;
> >> +	}
> >> +
> >> +	mutex_lock(&vdev->igate);
> >> +	vdev->aer_recovering = false;
> >> +	mutex_unlock(&vdev->igate);
> >> +
> >> +	complete_all(&vdev->aer_completion);
> >> +
> >> +	vfio_device_put(device);
> >> +}
> >> +
> >>  static const struct pci_error_handlers vfio_err_handlers = {
> >>  	.error_detected = vfio_pci_aer_err_detected,
> >> +	.resume         = vfio_pci_aer_resume,
> >>  };
> >>  
> >>  static struct pci_driver vfio_pci_driver = {
> >> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> >> index 8a7d546..ba8471f 100644
> >> --- a/drivers/vfio/pci/vfio_pci_private.h
> >> +++ b/drivers/vfio/pci/vfio_pci_private.h
> >> @@ -83,6 +83,8 @@ struct vfio_pci_device {
> >>  	bool			bardirty;
> >>  	bool			has_vga;
> >>  	bool			needs_reset;
> >> +	bool			aer_recovering;
> >> +	struct completion	aer_completion;
> >>  	struct pci_saved_state	*pci_saved_state;
> >>  	int			refcnt;
> >>  	struct eventfd_ctx	*err_trigger;
> >> -- 
> >> 1.8.3.1
> >>
> >>
> > 
> > How about some explanation about what is going on here?  All these
> > changes seem racy since any number of errors can trigger at any time.
> > 
> 
>

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#1556133

FromCao jin <caoj.fnst@cn.fujitsu.com>
Date2017-01-11 02:50 +0100
Message-ID<sYgd3-tK-1@gated-at.bofh.it>
In reply to#1555585

On 01/10/2017 11:11 PM, Michael S. Tsirkin wrote:
> On Tue, Jan 10, 2017 at 07:46:17PM +0800, Cao jin wrote:
>>
>>
>> On 01/10/2017 07:04 AM, Michael S. Tsirkin wrote:
>>> On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote:
>>>> Support serious device error recovery
>>>
>>> serious?
>>>
>>
>> Sorry for my poor vocabulary if it confuses people. I wanted to express
>> the meaning that: vfio-pci actually cannot do a real recovery for device
>> even if it provides the callbacks, it relies on the user to do a
>> effective(or word "serious"?) recovery.
>>
>> Welcome the amendment on the commit log.
> 
> It's up to Alex, maybe he's able to figure it all out from
> code, but the rest of us could benefit from a description
> of what the patch does from userspace point of view.
> 
> Also, is it a pre-requisite of the userspace patches you posted?
> 

Yes, it is.
-- 
Sincerely,
Cao jin

>>>>
>>>> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
>>>> ---
>>>>  drivers/vfio/pci/vfio_pci.c         | 70 +++++++++++++++++++++++++++++++++++--
>>>>  drivers/vfio/pci/vfio_pci_private.h |  2 ++
>>>>  2 files changed, 70 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>>>> index 712a849..752af20 100644
>>>> --- a/drivers/vfio/pci/vfio_pci.c
>>>> +++ b/drivers/vfio/pci/vfio_pci.c
>>>> @@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data,
>>>>  {
>>>>  	struct vfio_pci_device *vdev = device_data;
>>>>  	unsigned long minsz;
>>>> +	int ret;
>>>> +
>>>> +	if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
>>>> +	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
>>>> +		ret = wait_for_completion_interruptible(
>>>> +			&vdev->aer_completion);
>>>
>>> don't split it like that.
>>>
>>>> +		if (ret)
>>>> +			return ret;
>>>> +	}
>>>>  
>>>>  	if (cmd == VFIO_DEVICE_GET_INFO) {
>>>>  		struct vfio_device_info info;
>>>> @@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
>>>>  {
>>>>  	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
>>>>  	struct vfio_pci_device *vdev = device_data;
>>>> +	int ret;
>>>> +
>>>> +	/* block all kinds of access during host recovery */
>>>> +	if (vdev->aer_recovering) {
>>>> +		ret = wait_for_completion_interruptible(
>>>> +			&vdev->aer_completion);
>>>> +		if (ret)
>>>> +			return ret;
>>>> +	}
>>>>  
>>>>  	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
>>>>  		return -EINVAL;
>>>> @@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>>>  	vdev->irq_type = VFIO_PCI_NUM_IRQS;
>>>>  	mutex_init(&vdev->igate);
>>>>  	spin_lock_init(&vdev->irqlock);
>>>> +	init_completion(&vdev->aer_completion);
>>>>  
>>>>  	ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
>>>>  	if (ret) {
>>>> @@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>>>  {
>>>>  	struct vfio_pci_device *vdev;
>>>>  	struct vfio_device *device;
>>>> +	u32 uncor_status;
>>>> +	unsigned int aer_cap_offset;
>>>> +	int ret;
>>>>  
>>>>  	device = vfio_device_get_from_dev(&pdev->dev);
>>>>  	if (device == NULL)
>>>> @@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>>>  		return PCI_ERS_RESULT_DISCONNECT;
>>>>  	}
>>>>  
>>>> +	/*
>>>> +	 * get device's uncorrectable error status as soon as possible,
>>>
>>> should be "Get".
>>>
>>>> +	 * and signal it to user space. The later we read it, the possibility
>>>> +	 * the register value is mangled grows.
>>>> +	 */
>>>> +	aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR);
>>>> +	ret = pci_read_config_dword(vdev->pdev, aer_cap_offset +
>>>> +                                    PCI_ERR_UNCOR_STATUS, &uncor_status);
>>>> +        if (ret)
>>>> +                return PCI_ERS_RESULT_DISCONNECT;
>>>> +
>>>> +	pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed
>>>
>>> Pls drop this.
>>>
>>>>  	mutex_lock(&vdev->igate);
>>>>  
>>>> -	if (vdev->err_trigger)
>>>> -		eventfd_signal(vdev->err_trigger, 1);
>>>> +	vdev->aer_recovering = true;
>>>> +	reinit_completion(&vdev->aer_completion);
>>>> +
>>>> +	if (vdev->err_trigger && uncor_status) {
>>>> +		pr_info("device %d signal uncor status 0x%x to user",
>>>> +			pdev->devfn, uncor_status);
>>>> +		/* signal uncorrectable error status to user space */
>>>> +		eventfd_signal(vdev->err_trigger, uncor_status);
>>>> +        }
>>>>  
>>>>  	mutex_unlock(&vdev->igate);
>>>>  
>>>> @@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>>>  	return PCI_ERS_RESULT_CAN_RECOVER;
>>>>  }
>>>>  
>>>> +static void vfio_pci_aer_resume(struct pci_dev *pdev)
>>>> +{
>>>> +	struct vfio_pci_device *vdev;
>>>> +	struct vfio_device *device;
>>>> +
>>>> +	device = vfio_device_get_from_dev(&pdev->dev);
>>>> +	if (device == NULL)
>>>> +		return;
>>>> +
>>>> +	vdev = vfio_device_data(device);
>>>> +	if (vdev == NULL) {
>>>> +		vfio_device_put(device);
>>>> +		return;
>>>> +	}
>>>> +
>>>> +	mutex_lock(&vdev->igate);
>>>> +	vdev->aer_recovering = false;
>>>> +	mutex_unlock(&vdev->igate);
>>>> +
>>>> +	complete_all(&vdev->aer_completion);
>>>> +
>>>> +	vfio_device_put(device);
>>>> +}
>>>> +
>>>>  static const struct pci_error_handlers vfio_err_handlers = {
>>>>  	.error_detected = vfio_pci_aer_err_detected,
>>>> +	.resume         = vfio_pci_aer_resume,
>>>>  };
>>>>  
>>>>  static struct pci_driver vfio_pci_driver = {
>>>> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
>>>> index 8a7d546..ba8471f 100644
>>>> --- a/drivers/vfio/pci/vfio_pci_private.h
>>>> +++ b/drivers/vfio/pci/vfio_pci_private.h
>>>> @@ -83,6 +83,8 @@ struct vfio_pci_device {
>>>>  	bool			bardirty;
>>>>  	bool			has_vga;
>>>>  	bool			needs_reset;
>>>> +	bool			aer_recovering;
>>>> +	struct completion	aer_completion;
>>>>  	struct pci_saved_state	*pci_saved_state;
>>>>  	int			refcnt;
>>>>  	struct eventfd_ctx	*err_trigger;
>>>> -- 
>>>> 1.8.3.1
>>>>
>>>>
>>>
>>> How about some explanation about what is going on here?  All these
>>> changes seem racy since any number of errors can trigger at any time.
>>>
>>
>>
> 
> 
> .
> 

-- 
Sincerely,
Cao jin

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#1557573

From"Michael S. Tsirkin" <mst@redhat.com>
Date2017-01-12 17:30 +0100
Message-ID<sYQqd-69X-7@gated-at.bofh.it>
In reply to#1556133
On Wed, Jan 11, 2017 at 09:53:25AM +0800, Cao jin wrote:
> 
> 
> On 01/10/2017 11:11 PM, Michael S. Tsirkin wrote:
> > On Tue, Jan 10, 2017 at 07:46:17PM +0800, Cao jin wrote:
> >>
> >>
> >> On 01/10/2017 07:04 AM, Michael S. Tsirkin wrote:
> >>> On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote:
> >>>> Support serious device error recovery
> >>>
> >>> serious?
> >>>
> >>
> >> Sorry for my poor vocabulary if it confuses people. I wanted to express
> >> the meaning that: vfio-pci actually cannot do a real recovery for device
> >> even if it provides the callbacks, it relies on the user to do a
> >> effective(or word "serious"?) recovery.
> >>
> >> Welcome the amendment on the commit log.
> > 
> > It's up to Alex, maybe he's able to figure it all out from
> > code, but the rest of us could benefit from a description
> > of what the patch does from userspace point of view.
> > 
> > Also, is it a pre-requisite of the userspace patches you posted?
> > 
> 
> Yes, it is.

Looks like it's time for another design document :)

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