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

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Message-ID: <393b09e8-4631-90f4-6cae-755d1c2813f2@nvidia.com>
Date:   Wed, 2 Nov 2016 13:36:47 +0530
From:   Kirti Wankhede <kwankhede@...dia.com>
To:     Jike Song <jike.song@...el.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 10/28/2016 11:31 AM, Jike Song wrote:
> 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?
> 

Sorry, my git was synced just few changes behind this change. I'll make
sure that I test the patch set at top of tree.

Thanks,
Kirti