linux-kernel - Re: [Qemu-devel] [PATCH v2 2/2] vfio : add aer process

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Date:	Mon, 1 Aug 2016 10:14:06 +0800
From:	Zhou Jie <zhoujie2011@...fujitsu.com>
To:	Alex Williamson <alex.williamson@...hat.com>
CC:	<fan.chen@...ystack.cn>, <linux-kernel@...r.kernel.org>,
	<qemu-devel@...gnu.org>, Chen Fan <chen.fan.fnst@...fujitsu.com>,
	<izumi.taku@...fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH v2 2/2] vfio : add aer process

Hi, Alex

On 2016/7/30 1:12, Alex Williamson wrote:
> On Tue, 19 Jul 2016 15:32:43 +0800
> Zhou Jie <zhoujie2011@...fujitsu.com> wrote:
>
>> From: Chen Fan <chen.fan.fnst@...fujitsu.com>
>>
>> During aer err occurs and resume do following to
>> protect device from being accessed.
>> 1. Make config space read only.
>> 2. Disable INTx/MSI Interrupt.
>> 3. Do nothing for bar regions.
>>
>> Signed-off-by: Zhou Jie <zhoujie2011@...fujitsu.com>
>> ---
>>  drivers/vfio/pci/vfio_pci.c         | 30 ++++++++++++++++++++++++++++++
>>  drivers/vfio/pci/vfio_pci_private.h |  2 ++
>>  include/uapi/linux/vfio.h           |  2 ++
>>  3 files changed, 34 insertions(+)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
>> index 2d12b03..dd96b60 100644
>> --- a/drivers/vfio/pci/vfio_pci.c
>> +++ b/drivers/vfio/pci/vfio_pci.c
>> @@ -318,6 +318,7 @@ static int vfio_pci_open(void *device_data)
>>  		return -ENODEV;
>>
>>  	mutex_lock(&driver_lock);
>> +	init_completion(&vdev->aer_error_completion);
>>
>>  	if (!vdev->refcnt) {
>>  		ret = vfio_pci_enable(vdev);
>> @@ -571,6 +572,16 @@ static long vfio_pci_ioctl(void *device_data,
>>  	struct vfio_pci_device *vdev = device_data;
>>  	unsigned long minsz;
>>
>> +	if (vdev->aer_error_in_progress && (cmd == VFIO_DEVICE_SET_IRQS ||
>> +	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
>> +		int ret;
>> +		ret = wait_for_completion_interruptible(
>> +			&vdev->aer_error_completion);
>> +		if (ret) {
>> +			return ret;
>> +		}
>
> No brackets necessary.
>
>> +	}
>> +
>>  	if (cmd == VFIO_DEVICE_GET_INFO) {
>>  		struct vfio_device_info info;
>>
>> @@ -587,6 +598,10 @@ static long vfio_pci_ioctl(void *device_data,
>>  		if (vdev->reset_works)
>>  			info.flags |= VFIO_DEVICE_FLAGS_RESET;
>>
>> +		info.flags |= VFIO_DEVICE_FLAGS_AERPROCESS;
>> +		if (vdev->aer_error_in_progress)
>> +			info.flags |= VFIO_DEVICE_FLAGS_INAERPROCESS;
>> +
>>  		info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions;
>>  		info.num_irqs = VFIO_PCI_NUM_IRQS;
>>
>> @@ -996,6 +1011,14 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
>>
>>  	switch (index) {
>>  	case VFIO_PCI_CONFIG_REGION_INDEX:
>> +		if (vdev->aer_error_in_progress && iswrite) {
>> +			int ret;
>> +			ret = wait_for_completion_interruptible(
>> +				&vdev->aer_error_completion);
>> +			if (ret) {
>> +				return ret;
>> +			}
>> +		}
>>  		return vfio_pci_config_rw(vdev, buf, count, ppos, iswrite);
>>
>>  	case VFIO_PCI_ROM_REGION_INDEX:
>> @@ -1226,6 +1249,10 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
>>
>>  	mutex_lock(&vdev->igate);
>>
>> +	vdev->aer_error_in_progress = true;
>> +	vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |
>> +				VFIO_IRQ_SET_ACTION_TRIGGER,
>> +				vdev->irq_type, 0, 0, NULL);
>>  	if (vdev->err_trigger)
>>  		eventfd_signal(vdev->err_trigger, 1);
>>
>> @@ -1252,6 +1279,9 @@ static void vfio_pci_aer_resume(struct pci_dev *pdev)
>>  	}
>>
>>  	mutex_lock(&vdev->igate);
>> +
>> +	vdev->aer_error_in_progress = false;
>> +	complete_all(&vdev->aer_error_completion);
>>  	if (vdev->resume_trigger)
>>  		eventfd_signal(vdev->resume_trigger, 1);
>>
>> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
>> index 80d4ddd..2f151f5 100644
>> --- a/drivers/vfio/pci/vfio_pci_private.h
>> +++ b/drivers/vfio/pci/vfio_pci_private.h
>> @@ -84,6 +84,8 @@ struct vfio_pci_device {
>>  	bool			has_vga;
>>  	bool			needs_reset;
>>  	bool			nointx;
>> +	bool			aer_error_in_progress;
>> +	struct completion	aer_error_completion;
>>  	struct pci_saved_state	*pci_saved_state;
>>  	int			refcnt;
>>  	struct eventfd_ctx	*err_trigger;
>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>> index 34ab138..276ce50 100644
>> --- a/include/uapi/linux/vfio.h
>> +++ b/include/uapi/linux/vfio.h
>> @@ -198,6 +198,8 @@ struct vfio_device_info {
>>  #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
>>  #define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2)	/* vfio-platform device */
>>  #define VFIO_DEVICE_FLAGS_AMBA  (1 << 3)	/* vfio-amba device */
>> +#define VFIO_DEVICE_FLAGS_AERPROCESS  (1 << 4)	/* support aer error progress */
>> +#define VFIO_DEVICE_FLAGS_INAERPROCESS  (1 << 5)/* status in aer error progress */
>>  	__u32	num_regions;	/* Max region index + 1 */
>>  	__u32	num_irqs;	/* Max IRQ index + 1 */
>>  };
>
> Clearly this has only been tested for a single instance of an AER error
> event and resume per device.  Are the things you're intending to block
> actually blocked for subsequent events?  Note how complete_all() fills
> the done field to let all current and future waiters go through and
> nowhere is there a call to reinit_completion() to drain that path.
> Thanks,
>
> Alex

Do you mean this condition?

For device 1:
error1 occurs ---- error1 resumes
     error2 occurs ---- error2 resumes
         error3 occurs ---- error3 resumes

In current code, I do complete_all() when error1 resumes.
And this will unblock the device
when error2 and error3 are still be processed.

Sincerely
ZhouJie