Re: [Xen-devel] [PATCH v2 1/9] mm: Introduce new vm_insert_range API

[Mike Rapoport <rppt@xxxxxxxxxxxxx>]

On Mon, Dec 03, 2018 at 09:51:45AM +0530, Souptick Joarder wrote:
> Hi Mike,
> 
> On Sun, Dec 2, 2018 at 4:43 PM Mike Rapoport <rppt@xxxxxxxxxxxxx> wrote:
> >
> > On Sun, Dec 02, 2018 at 11:49:44AM +0530, Souptick Joarder wrote:
> > > Previouly drivers have their own way of mapping range of
> > > kernel pages/memory into user vma and this was done by
> > > invoking vm_insert_page() within a loop.
> > >
> > > As this pattern is common across different drivers, it can
> > > be generalized by creating a new function and use it across
> > > the drivers.
> > >
> > > vm_insert_range is the new API which will be used to map a
> > > range of kernel memory/pages to user vma.
> > >
> > > This API is tested by Heiko for Rockchip drm driver, on rk3188,
> > > rk3288, rk3328 and rk3399 with graphics.
> > >
> > > Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> > > Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> > > Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
> > > ---
> > >  include/linux/mm_types.h |  3 +++
> > >  mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
> > >  mm/nommu.c               |  7 +++++++
> > >  3 files changed, 48 insertions(+)
> > >
> > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > > index 5ed8f62..15ae24f 100644
> > > --- a/include/linux/mm_types.h
> > > +++ b/include/linux/mm_types.h
> > > @@ -523,6 +523,9 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, 
> > > struct mm_struct *mm,
> > >  extern void tlb_finish_mmu(struct mmu_gather *tlb,
> > >                               unsigned long start, unsigned long end);
> > >
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count);
> > > +
> >
> > This seem to belong to include/linux/mm.h, near vm_insert_page()
> 
> Ok, I will change it. Apart from this change does it looks good ?

With this change you can add

Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
 
> >
> > >  static inline void init_tlb_flush_pending(struct mm_struct *mm)
> > >  {
> > >       atomic_set(&mm->tlb_flush_pending, 0);
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index 15c417e..84ea46c 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, 
> > > unsigned long addr,
> > >  }
> > >
> > >  /**
> > > + * vm_insert_range - insert range of kernel pages into user vma
> > > + * @vma: user vma to map to
> > > + * @addr: target user address of this page
> > > + * @pages: pointer to array of source kernel pages
> > > + * @page_count: number of pages need to insert into user vma
> > > + *
> > > + * This allows drivers to insert range of kernel pages they've allocated
> > > + * into a user vma. This is a generic function which drivers can use
> > > + * rather than using their own way of mapping range of kernel pages into
> > > + * user vma.
> > > + *
> > > + * If we fail to insert any page into the vma, the function will return
> > > + * immediately leaving any previously-inserted pages present.  Callers
> > > + * from the mmap handler may immediately return the error as their caller
> > > + * will destroy the vma, removing any successfully-inserted pages. Other
> > > + * callers should make their own arrangements for calling unmap_region().
> > > + *
> > > + * Context: Process context. Called by mmap handlers.
> > > + * Return: 0 on success and error code otherwise
> > > + */
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count)
> > > +{
> > > +     unsigned long uaddr = addr;
> > > +     int ret = 0, i;
> > > +
> > > +     for (i = 0; i < page_count; i++) {
> > > +             ret = vm_insert_page(vma, uaddr, pages[i]);
> > > +             if (ret < 0)
> > > +                     return ret;
> > > +             uaddr += PAGE_SIZE;
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +EXPORT_SYMBOL(vm_insert_range);
> > > +
> > > +/**
> > >   * vm_insert_page - insert single page into user vma
> > >   * @vma: user vma to map to
> > >   * @addr: target user address of this page
> > > diff --git a/mm/nommu.c b/mm/nommu.c
> > > index 749276b..d6ef5c7 100644
> > > --- a/mm/nommu.c
> > > +++ b/mm/nommu.c
> > > @@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, 
> > > unsigned long addr,
> > >  }
> > >  EXPORT_SYMBOL(vm_insert_page);
> > >
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count)
> > > +{
> > > +     return -EINVAL;
> > > +}
> > > +EXPORT_SYMBOL(vm_insert_range);
> > > +
> > >  /*
> > >   *  sys_brk() for the most part doesn't need the global kernel
> > >   *  lock, except when an application is doing something nasty
> > > --
> > > 1.9.1
> > >
> >
> > --
> > Sincerely yours,
> > Mike.
> >
> 

-- 
Sincerely yours,
Mike.


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