Re: [Xen-devel] [PATCH] xen/arm: Correctly implement domain_page_map_to_mfn

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 5 Feb 2014, Julien Grall wrote:
> The function domain_page_map_to_mfn can be used to translate a virtual
> address mapped by both map_domain_page and map_domain_page_global.
> The former is using vmap to map the mfn, therefore domain_page_map_to_mfn
> will always fail because the address is not in DOMHEAP range.
> 
> Check if the address is in vmap range and use __pa to translate it.
> 
> This patch fix guest shutdown when the event fifo is used.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxx>

It looks good to me.

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


> ---
>     This is a bug fix for Xen 4.4. Without this patch, it's impossible to
> use Linux 3.14 (and higher) as guest with the event fifo driver.
> ---
>  xen/arch/arm/mm.c |   10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 127cce0..bdca68a 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -325,11 +325,15 @@ void unmap_domain_page(const void *va)
>      local_irq_restore(flags);
>  }
>  
> -unsigned long domain_page_map_to_mfn(const void *va)
> +unsigned long domain_page_map_to_mfn(const void *ptr)
>  {
> +    unsigned long va = (unsigned long)ptr;
>      lpae_t *map = this_cpu(xen_dommap);
> -    int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
> -    unsigned long offset = ((unsigned long)va>>THIRD_SHIFT) & 
> LPAE_ENTRY_MASK;
> +    int slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
> +    unsigned long offset = (va>>THIRD_SHIFT) & LPAE_ENTRY_MASK;
> +
> +    if ( va >= VMAP_VIRT_START && va < VMAP_VIRT_END )
> +        return virt_to_mfn(va);
>  
>      ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES);
>      ASSERT(map[slot].pt.avail != 0);
> -- 
> 1.7.10.4
> 

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