Re: [PATCH v1 4/7] vfio: ap: AP Queue Interrupt Control VFIO ioctl calls

[Tony Krowiak <akrowiak@linux.ibm.com>]

On 11/7/18 5:31 PM, Pierre Morel wrote:
> On 06/11/2018 21:21, Tony Krowiak wrote:
>> On 10/31/18 2:12 PM, Pierre Morel wrote:
>>> This is the implementation of the VFIO ioctl calls to handle
>>> the AQIC interception and use GISA to handle interrupts.
>>>
>>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>>> ---
>>>   drivers/s390/crypto/vfio_ap_ops.c | 95 +++++++++++++++++++++++++++++++
>>>   1 file changed, 95 insertions(+)
>>>
>>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c 
>>> b/drivers/s390/crypto/vfio_ap_ops.c
>>> index 272ef427dcc0..f68102163bf4 100644
>>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>>> @@ -895,12 +895,107 @@ static int 
>>> vfio_ap_mdev_get_device_info(unsigned long arg)
>>>       return copy_to_user((void __user *)arg, &info, minsz);
>>>   }
>>> +static int ap_ioctl_setirq(struct ap_matrix_mdev *matrix_mdev,
>>
>> In keeping with the other function names in this file, how about
>> naming this function vfio_ap_mdev_setirq???
> 
> OK, agreed.
> 
>>
>>> +               struct vfio_ap_aqic *parm)
>>> +{
>>> +    struct aqic_gisa aqic_gisa = reg2aqic(0);
>>> +    struct kvm_s390_gisa *gisa = matrix_mdev->kvm->arch.gisa;
>>> +    struct ap_status ap_status = reg2status(0);
>>> +    unsigned long p;
>>> +    int ret = -1;
>>> +    int apqn;
>>> +    uint32_t gd;
>>> +
>>> +    apqn = (int)(parm->cmd & 0xffff);
>>> +
>>> +    gd = matrix_mdev->kvm->vcpus[0]->arch.sie_block->gd;
>>> +    if (gd & 0x01)
>>> +        aqic_gisa.f = 1;
>>> +    aqic_gisa.gisc = matrix_mdev->gisc;
>>
>> Can't you get this value from parm? I don't see any relationship
>> between the mdev device and gisc, why store it there?
> 
> The idea is that we may want to report this value to the admin or as 
> debug information, so I wanted to keep track of it.

It can be added if/when that is implemented. As of now, it is not needed.

> 
>>
>>> +    aqic_gisa.isc = GAL_ISC;
>>> +    aqic_gisa.ir = 1;
>>> +    aqic_gisa.gisao = gisa->next_alert >> 4;
>>> +
>>> +    p = (unsigned long) page_address(matrix_mdev->map->page);
>>> +    p += (matrix_mdev->map->guest_addr & 0x0fff);
>>> +
>>> +    ret = ap_host_aqic((uint64_t)apqn, aqic2reg(aqic_gisa), p);
>>> +    parm->status = ret;
>>> +
>>> +    ap_status = reg2status(ret);
>>> +    return (ap_status.rc) ? -EIO : 0;
>>> +}
>>> +
>>> +static int ap_ioctl_clrirq(struct ap_matrix_mdev *matrix_mdev,
>>> +               struct vfio_ap_aqic *parm)
>>
>> In keeping with the other function names in this file, how about
>> naming this function vfio_ap_mdev_clrirq, or better yet,
>> vfio_ap_mdev_clear_irq???
> 
> agreed too.
> 
>>
>>> +{
>>> +    struct aqic_gisa aqic_gisa = reg2aqic(0);
>>> +    struct ap_status ap_status = reg2status(0) > +    int apqn;
>>> +    int retval;
>>> +    uint32_t gd;
>>> +
>>> +    apqn = (int)(parm->cmd & 0xffff);
>>> +
>>> +    gd = matrix_mdev->kvm->vcpus[0]->arch.sie_block->gd;
>>> +    if (gd & 0x01)
>>> +        aqic_gisa.f = 1;
>>> +    aqic_gisa.ir = 0;
>>> +
>>> +    retval = ap_host_aqic((uint64_t)apqn, aqic2reg(aqic_gisa), 0);
>>> +    parm->status = retval;
>>> +
>>> +    ap_status = reg2status(retval);
>>> +    return (ap_status.rc) ? -EIO : 0;
>>> +}
>>> +
>>>   static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
>>>                       unsigned int cmd, unsigned long arg)
>>>   {
>>>       int ret;
>>> +    struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
>>> +    struct s390_io_adapter *adapter;
>>> +    struct vfio_ap_aqic parm;
>>> +    struct s390_map_info *map;
>>> +    int apqn, found = 0;
>>>       switch (cmd) {
>>> +    case VFIO_AP_SET_IRQ:
>>> +        if (copy_from_user(&parm, (void __user *)arg, sizeof(parm)))
>>> +            return -EFAULT;
>>> +        apqn = (int)(parm.cmd & 0xffff);
>>> +        parm.status &= 0x00000000ffffffffUL;
>>> +        matrix_mdev->gisc = parm.status & 0x07;
>>
>> It seems that the only reason for the 'gisc' field in matrix_mdev
>> is to pass the value to the ap_ioctl_setirq() function. Since the
>> gisc has nothing to do with the mdev device and the 'parm' is being
>> passed to ap_ioctl_setirq(), why not just eliminate the
>> matrix_mdev->gisc field and get it from the 'parm' parameter in
>> ap_ioctl_setirq()?
> 
> OK, seems better.
> 
>>
>>> +        /* find the adapter */ap_ioctl_setirq()
>>> +        adapter = matrix_mdev->kvm->arch.adapters[parm.adapter_id];
>>> +        if (!adapter)
>>> +            return -ENOENT;
>>> +        down_write(&adapter->maps_lock);
>>> +        list_for_each_entry(map, &adapter->maps, list) {
>>> +            if (map->guest_addr == parm.nib) {
>>> +                found = 1;
>>> +                break;
>>> +            }
>>> +        }
>>> +        up_write(&adapter->maps_lock);
>>> +
>>> +        if (!found)
>>> +            return -EINVAL;
>>> +
>>> +        matrix_mdev->map = map;
>>
>> See my comment above about matrix_mdev->gisc. Can't we just get rid
>> of the matrix_mdev->map field and pass the map into the
>> ap_ioctl_setirq() function?
> 
> or calculate it from parm... as we give parm as argument to this function

Better yet.

> 
>>
>>> +        ret = ap_ioctl_setirq(matrix_mdev, &parm);
>>> +        parm.status &= 0x00000000ffffffffUL;
>>> +        if (copy_to_user((void __user *)arg, &parm, sizeof(parm)))
>>> +            return -EFAULT;
>>> +
>>> +        break;
>>
>> IMHO, the case statements should only determine which ioctl is being
>> invoked and call the appropriate function to handle it. All of the above
>> code could be in an intermediate function called from this case
>> statement, thus reducing the case to calling the intermediate function.
> 
> OK, I can do so, however I would like to let the __user access here.

I can live with that although I prefer the one liner here.

> 
>>
>>> +    case VFIO_AP_CLEAR_IRQ:
>>> +        if (copy_from_user(&parm, (void __user *)arg, sizeof(parm)))
>>> +            return -EFAULT;
>>> +        ret = ap_ioctl_clrirq(matrix_mdev, &parm);
>>> +        if (copy_to_user((void __user *)arg, &parm, sizeof(parm)))
>>> +            return -EFAULT;
>>> +        break;
>>>       case VFIO_DEVICE_GET_INFO:
>>>           ret = vfio_ap_mdev_get_device_info(arg);
>>>           break;
>>>
>>
> 
> Thanks
> Pierre
>