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

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Message-ID: <78a52b28-40c6-076d-030e-6eb4c343d73a@nvidia.com>
Date:   Thu, 27 Oct 2016 17:54:58 +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 10/27/2016 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);


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;
>>  
>>