Re: [PATCH V7 3/7] vfio/type1: track locked_vm per dma

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Dec 20, 2022 at 12:39:21PM -0800, Steve Sistare wrote:
> Track locked_vm per dma struct, and create a new subroutine, both for use
> in a subsequent patch.  No functional change.
> 
> Fixes: c3cbab24db38 ("vfio/type1: implement interfaces to update vaddr")
> Cc: stable@vger.kernel.org
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 71f980b..588d690 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -101,6 +101,7 @@ struct vfio_dma {
>  	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
>  	unsigned long		*bitmap;
>  	struct mm_struct	*mm;
> +	long			locked_vm;

Why is it long? Can it be negative?

>  };
>  
>  struct vfio_batch {
> @@ -413,22 +414,21 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
>  	return ret;
>  }
>  
> -static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
> +static int mm_lock_acct(struct task_struct *task, struct mm_struct *mm,
> +			bool lock_cap, long npage, bool async)
>  {

Now async is even more confusing, the caller really should have a
valid handle on the mm before using it as an argument like this.

Jason