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

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Message-ID: <5811EF08.5000602@intel.com>
Date:   Thu, 27 Oct 2016 20:11:52 +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 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?

--
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;
>  
>