Re: [Xen-devel] [v2 02/16] xen/arm: raw_copy_to_guest_helper: Rework the prototype and rename it

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 12 Dec 2017, Julien Grall wrote:
> All the helpers within arch/arm/guestcopy.c are doing the same things:
> copy data from/to the guest.
> 
> At the moment, the logic is duplicated in each helpers making more
> difficult to implement new variant.
> 
> The first step for the consolidation is to get a common prototype and a
> base. For convenience (it is at the beginning of the file!),
> raw_copy_to_guest_helper is chosen.
> 
> The function is now renamed copy_guest to show it will be a
> generic function to copy data from/to the guest. Note that for now, only
> copying to guest virtual address is supported. Follow-up patches will
> extend the support.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>     Changes in v2:
>         - Use vaddr_t
>         - Use uint64_t for addr in copy_guest
>         - Add a BUILD_BUG_ON to make sure vaddr_t fit in uint64_t.
> ---
>  xen/arch/arm/guestcopy.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/arch/arm/guestcopy.c b/xen/arch/arm/guestcopy.c
> index 2620e659b4..08d0fa0a83 100644
> --- a/xen/arch/arm/guestcopy.c
> +++ b/xen/arch/arm/guestcopy.c
> @@ -7,11 +7,13 @@
>  
>  #define COPY_flush_dcache   (1U << 0)
>  
> -static unsigned long raw_copy_to_guest_helper(void *to, const void *from,
> -                                              unsigned len, int flags)
> +static unsigned long copy_guest(void *buf, uint64_t addr, unsigned int len,
> +                                unsigned int flags)
>  {
>      /* XXX needs to handle faults */
> -    unsigned offset = (vaddr_t)to & ~PAGE_MASK;
> +    unsigned offset = addr & ~PAGE_MASK;
> +
> +    BUILD_BUG_ON((sizeof(addr)) < sizeof(vaddr_t));
>  
>      while ( len )
>      {
> @@ -19,21 +21,21 @@ static unsigned long raw_copy_to_guest_helper(void *to, 
> const void *from,
>          unsigned size = min(len, (unsigned)PAGE_SIZE - offset);
>          struct page_info *page;
>  
> -        page = get_page_from_gva(current, (vaddr_t) to, GV2M_WRITE);
> +        page = get_page_from_gva(current, addr, GV2M_WRITE);
>          if ( page == NULL )
>              return len;
>  
>          p = __map_domain_page(page);
>          p += offset;
> -        memcpy(p, from, size);
> +        memcpy(p, buf, size);
>          if ( flags & COPY_flush_dcache )
>              clean_dcache_va_range(p, size);
>  
>          unmap_domain_page(p - offset);
>          put_page(page);
>          len -= size;
> -        from += size;
> -        to += size;
> +        buf += size;
> +        addr += size;
>          /*
>           * After the first iteration, guest virtual address is correctly
>           * aligned to PAGE_SIZE.
> @@ -46,13 +48,13 @@ static unsigned long raw_copy_to_guest_helper(void *to, 
> const void *from,
>  
>  unsigned long raw_copy_to_guest(void *to, const void *from, unsigned len)
>  {
> -    return raw_copy_to_guest_helper(to, from, len, 0);
> +    return copy_guest((void *)from, (vaddr_t)to, len, 0);
>  }
>  
>  unsigned long raw_copy_to_guest_flush_dcache(void *to, const void *from,
>                                               unsigned len)
>  {
> -    return raw_copy_to_guest_helper(to, from, len, COPY_flush_dcache);
> +    return copy_guest((void *)from, (vaddr_t)to, len, COPY_flush_dcache);
>  }
>  
>  unsigned long raw_clear_guest(void *to, unsigned len)
> -- 
> 2.11.0
> 

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