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

[Pierre Morel <pmorel@linux.ibm.com>]

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.

> 
>> +    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

> 
>> +        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.

> 
>> +    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

-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany