On 10/21/2016 8:06 PM, Alex Williamson wrote:
> On Fri, 21 Oct 2016 15:49:07 +0800
> Jike Song <jike.song@xxxxxxxxx> wrote:
>
>> On 10/18/2016 05:22 AM, Kirti Wankhede wrote:
>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
>>> index 2ba19424e4a1..5d67058a611d 100644
>>> --- a/drivers/vfio/vfio_iommu_type1.c
>>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> [snip]
>>> static int vfio_iommu_type1_attach_group(void *iommu_data,
>>> struct iommu_group *iommu_group)
>>> {
>>> struct vfio_iommu *iommu = iommu_data;
>>> - struct vfio_group *group, *g;
>>> + struct vfio_group *group;
>>> struct vfio_domain *domain, *d;
>>> struct bus_type *bus = NULL;
>>> int ret;
>>> @@ -746,10 +1136,14 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>>> mutex_lock(&iommu->lock);
>>>
>>> list_for_each_entry(d, &iommu->domain_list, next) {
>>> - list_for_each_entry(g, &d->group_list, next) {
>>> - if (g->iommu_group != iommu_group)
>>> - continue;
>>> + if (find_iommu_group(d, iommu_group)) {
>>> + mutex_unlock(&iommu->lock);
>>> + return -EINVAL;
>>> + }
>>> + }
>>>
>>> + if (iommu->local_domain) {
>>> + if (find_iommu_group(iommu->local_domain, iommu_group)) {
>>> mutex_unlock(&iommu->lock);
>>> return -EINVAL;
>>> }
>>> @@ -769,6 +1163,30 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>>> if (ret)
>>> goto out_free;
>>>
>>> + if (IS_ENABLED(CONFIG_VFIO_MDEV) && !iommu_present(bus) &&
>>> + (bus == &mdev_bus_type)) {
>>
>> Hi Kirti,
>>
>> By refering mdev_bus_type directly you are making vfio_iommu_type1.ko depends
>> on mdev.ko, but in Kconfig doesn't guarantee the dependency. For example,
>> if CONFIG_VFIO_IOMMU_TYPE1=y and CONFIG_VFIO_MDEV=m, the building will fail.
>
> Good point, Jike. I don't think we want to make existing vfio modules
> dependent on mdev modules. I wonder if we can lookup the mdev_bus_type
> symbol w/o triggering the module load. Thanks,
>
Ok. Modifying the check as below works in above case:
mdev_bus = symbol_get(mdev_bus_type);
if (mdev_bus && (bus == mdev_bus) && !iommu_present(bus) ) {
symbol_put(mdev_bus_type);
...
}
Kirti
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