On 8/25/2016 2:52 PM, Dong Jia wrote:
> On Thu, 25 Aug 2016 09:23:53 +0530
> Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
>
> [...]
>
> Dear Kirti,
>
> I just rebased my vfio-ccw patches to this series.
> With a little fix, which was pointed it out in my reply to the #3
> patch, it works fine.
>
Thanks for update. Glad to know this works for you.
>> +static long vfio_mdev_unlocked_ioctl(void *device_data,
>> + unsigned int cmd, unsigned long arg)
>> +{
>> + int ret = 0;
>> + struct vfio_mdev *vmdev = device_data;
>> + struct parent_device *parent = vmdev->mdev->parent;
>> + unsigned long minsz;
>> +
>> + switch (cmd) {
>> + case VFIO_DEVICE_GET_INFO:
>> + {
>> + struct vfio_device_info info;
>> +
>> + minsz = offsetofend(struct vfio_device_info, num_irqs);
>> +
>> + if (copy_from_user(&info, (void __user *)arg, minsz))
>> + return -EFAULT;
>> +
>> + if (info.argsz < minsz)
>> + return -EINVAL;
>> +
>> + if (parent->ops->get_device_info)
>> + ret = parent->ops->get_device_info(vmdev->mdev, &info);
>> + else
>> + return -EINVAL;
>> +
>> + if (ret)
>> + return ret;
>> +
>> + if (parent->ops->reset)
>> + info.flags |= VFIO_DEVICE_FLAGS_RESET;
> Shouldn't this be done inside the get_device_info callback?
>
I would like Vendor driver to set device type only. Reset flag should be
set on basis of reset() callback provided.
>> +
>> + memcpy(&vmdev->dev_info, &info, sizeof(info));
>> +
>> + return copy_to_user((void __user *)arg, &info, minsz);
>> + }
> [...]
>
>> +
>> +static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
>> + size_t count, loff_t *ppos)
>> +{
>> + struct vfio_mdev *vmdev = device_data;
>> + struct mdev_device *mdev = vmdev->mdev;
>> + struct parent_device *parent = mdev->parent;
>> + unsigned int done = 0;
>> + int ret;
>> +
>> + if (!parent->ops->read)
>> + return -EINVAL;
>> +
>> + while (count) {
> Here, I have to say sorry to you guys for that I didn't notice the
> bad impact of this change to my patches during the v6 discussion.
>
> For vfio-ccw, I introduced an I/O region to input/output I/O
> instruction parameters and results for Qemu. The @count of these data
> currently is 140. So supporting arbitrary lengths in one shot here, and
> also in vfio_mdev_write, seems the better option for this case.
>
> I believe that if the pci drivers want to iterate in a 4 bytes step, you
> can do that in the parent read/write callbacks instead.
>
> What do you think?
>
I would like to know Alex's thought on this. He raised concern with this
approach in v6 reviews:
"But I think this is exploitable, it lets the user make the kernel
allocate an arbitrarily sized buffer."
Thanks,
Kirti
>> + size_t filled;
>> +
>> + if (count >= 4 && !(*ppos % 4)) {
>> + u32 val;
>> +
>> + ret = parent->ops->read(mdev, (char *)&val, sizeof(val),
>> + *ppos);
>> + if (ret <= 0)
>> + goto read_err;
>> +
>> + if (copy_to_user(buf, &val, sizeof(val)))
>> + goto read_err;
>> +
>> + filled = 4;
>> + } else if (count >= 2 && !(*ppos % 2)) {
>> + u16 val;
>> +
>> + ret = parent->ops->read(mdev, (char *)&val, sizeof(val),
>> + *ppos);
>> + if (ret <= 0)
>> + goto read_err;
>> +
>> + if (copy_to_user(buf, &val, sizeof(val)))
>> + goto read_err;
>> +
>> + filled = 2;
>> + } else {
>> + u8 val;
>> +
>> + ret = parent->ops->read(mdev, &val, sizeof(val), *ppos);
>> + if (ret <= 0)
>> + goto read_err;
>> +
>> + if (copy_to_user(buf, &val, sizeof(val)))
>> + goto read_err;
>> +
>> + filled = 1;
>> + }
>> +
>> + count -= filled;
>> + done += filled;
>> + *ppos += filled;
>> + buf += filled;
>> + }
>> +
>> + return done;
>> +
>> +read_err:
>> + return -EFAULT;
>> +}
> [...]
>
> --------
> Dong Jia
>
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