Re: [Qemu-devel] [PATCH v10 07/19] vfio iommu type1: Update argument of vaddr_get_pfn()

[Kirti Wankhede]

On 10/27/2016 5:41 PM, Jike Song wrote:
> On 10/27/2016 05:29 AM, Kirti Wankhede wrote:
>> Update arguments of vaddr_get_pfn() to take struct mm_struct *mm as input
>> argument.
>>
>> Signed-off-by: Kirti Wankhede <address@hidden>
>> Signed-off-by: Neo Jia <address@hidden>
>> Change-Id: I885fd4cd4a9f66f4ee2c1caf58267464ec239f52
>> ---
>>  drivers/vfio/vfio_iommu_type1.c | 25 ++++++++++++++++++-------
>>  1 file changed, 18 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c 
>> b/drivers/vfio/vfio_iommu_type1.c
>> index 72fee415044a..3d916b965492 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -228,20 +228,31 @@ static int put_pfn(unsigned long pfn, int prot)
>>      return 0;
>>  }
>>  
>> -static int vaddr_get_pfn(unsigned long vaddr, int prot, unsigned long *pfn)
>> +static int vaddr_get_pfn(struct mm_struct *remote_mm, unsigned long vaddr,
>> +                     int prot, unsigned long *pfn)
>>  {
>>      struct page *page[1];
>>      struct vm_area_struct *vma;
>> +    struct mm_struct *mm = (remote_mm ? remote_mm : current->mm);
>>      int ret = -EFAULT;
>>  
>> -    if (get_user_pages_fast(vaddr, 1, !!(prot & IOMMU_WRITE), page) == 1) {
>> +    if (remote_mm) {
>> +            down_read(&mm->mmap_sem);
>> +            ret = get_user_pages_remote(NULL, mm, vaddr, 1,
>> +                                    !!(prot & IOMMU_WRITE), 0, page, NULL);
> 
> Hi Kirti,
> 
> It seems that get_user_pages_remote has only 7 args but you somehow gives 8
> here?
> 

I had tested this patch with linux-next. It has 8 arguments, see mm/gup.c:

long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
                unsigned long start, unsigned long nr_pages,
                int write, int force, struct page **pages,
                struct vm_area_struct **vmas)
{
        return __get_user_pages_locked(tsk, mm, start, nr_pages, write,
force,
                                       pages, vmas, NULL, false,
                                       FOLL_TOUCH | FOLL_REMOTE);
}
EXPORT_SYMBOL(get_user_pages_remote);


Thanks,
Kirti

> --
> Thanks,
> Jike
> 
>> +            up_read(&mm->mmap_sem);
>> +    } else
>> +            ret = get_user_pages_fast(vaddr, 1,
>> +                                      !!(prot & IOMMU_WRITE), page);
>> +
>> +    if (ret == 1) {
>>              *pfn = page_to_pfn(page[0]);
>>              return 0;
>>      }
>>  
>> -    down_read(&current->mm->mmap_sem);
>> +    down_read(&mm->mmap_sem);
>>  
>> -    vma = find_vma_intersection(current->mm, vaddr, vaddr + 1);
>> +    vma = find_vma_intersection(mm, vaddr, vaddr + 1);
>>  
>>      if (vma && vma->vm_flags & VM_PFNMAP) {
>>              *pfn = ((vaddr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
>> @@ -249,7 +260,7 @@ static int vaddr_get_pfn(unsigned long vaddr, int prot, 
>> unsigned long *pfn)
>>                      ret = 0;
>>      }
>>  
>> -    up_read(&current->mm->mmap_sem);
>> +    up_read(&mm->mmap_sem);
>>  
>>      return ret;
>>  }
>> @@ -270,7 +281,7 @@ static long vfio_pin_pages(unsigned long vaddr, long 
>> npage,
>>      if (!current->mm)
>>              return -ENODEV;
>>  
>> -    ret = vaddr_get_pfn(vaddr, prot, pfn_base);
>> +    ret = vaddr_get_pfn(NULL, vaddr, prot, pfn_base);
>>      if (ret)
>>              return ret;
>>  
>> @@ -293,7 +304,7 @@ static long vfio_pin_pages(unsigned long vaddr, long 
>> npage,
>>      for (i = 1, vaddr += PAGE_SIZE; i < npage; i++, vaddr += PAGE_SIZE) {
>>              unsigned long pfn = 0;
>>  
>> -            ret = vaddr_get_pfn(vaddr, prot, &pfn);
>> +            ret = vaddr_get_pfn(NULL, vaddr, prot, &pfn);
>>              if (ret)
>>                      break;
>>  
>>