linux-kernel - Re: [PATCH v10 07/19] vfio iommu type1: Update argument of vaddr_get

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Message-ID: <5812E9AE.7010209@intel.com>
Date:   Fri, 28 Oct 2016 14:01:18 +0800
From:   Jike Song <jike.song@...el.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
CC:     alex.williamson@...hat.com, pbonzini@...hat.com, kraxel@...hat.com,
        cjia@...dia.com, qemu-devel@...gnu.org, kvm@...r.kernel.org,
        kevin.tian@...el.com, bjsdjshi@...ux.vnet.ibm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 07/19] vfio iommu type1: Update argument of vaddr_get_pfn()

On 10/27/2016 08:24 PM, Kirti Wankhede wrote:
> 
> 
> 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 <kwankhede@...dia.com>
>>> Signed-off-by: Neo Jia <cjia@...dia.com>
>>> 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);

It's queer. I checked:

https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/mm/gup.c

It still has 7 args.

I believe you have seen this change somewhere, would you share the repo url
and branch name of the linux-next you based on?

--
Thanks,
Jike