Re: [PATCH 2/2] arm/xen: Add misuse warning to virt_to_gfn

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 25 Aug 2020, Simon Leiner wrote:
> As virt_to_gfn uses virt_to_phys, it will return invalid addresses when
> used with vmalloc'd addresses. This patch introduces a warning, when
> virt_to_gfn is used in this way.
> 
> Signed-off-by: Simon Leiner <simon@xxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  include/xen/arm/page.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/xen/arm/page.h b/include/xen/arm/page.h
> index d7f6af50e200..b0d303b633d0 100644
> --- a/include/xen/arm/page.h
> +++ b/include/xen/arm/page.h
> @@ -76,7 +76,11 @@ static inline unsigned long bfn_to_pfn(unsigned long bfn)
>  #define bfn_to_local_pfn(bfn)        bfn_to_pfn(bfn)
>  
>  /* VIRT <-> GUEST conversion */
> -#define virt_to_gfn(v)               (pfn_to_gfn(virt_to_phys(v) >> 
> XEN_PAGE_SHIFT))
> +#define virt_to_gfn(v)                                                       
>   \
> +     ({                                                                     \
> +             WARN_ON_ONCE(is_vmalloc_addr(v));                              \
> +             pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT);                 \
> +     })
>  #define gfn_to_virt(m)               (__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
>  
>  /* Only used in PV code. But ARM guests are always HVM. */
> -- 
> 2.24.3 (Apple Git-128)
>