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Re: [PATCH v2 1/2] domain: fix misaligned unmap address in {,un}map_guest_area()


  • To: Roger Pau Monne <roger.pau@xxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 16 Oct 2023 14:30:12 +0200
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  • Cc: Henry Wang <Henry.Wang@xxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 16 Oct 2023 12:30:34 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 06.10.2023 15:00, Roger Pau Monne wrote:> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -1601,7 +1601,7 @@ int map_guest_area(struct vcpu *v, paddr_t gaddr, 
> unsigned int size,
>   unmap:
>      if ( pg )
>      {
> -        unmap_domain_page_global(map);
> +        unmap_domain_page_global((void *)((unsigned long)map & PAGE_MASK));
>          put_page_and_type(pg);
>      }
>  
> @@ -1634,7 +1634,7 @@ void unmap_guest_area(struct vcpu *v, struct guest_area 
> *area)
>  
>      if ( pg )
>      {
> -        unmap_domain_page_global(map);
> +        unmap_domain_page_global((void *)((unsigned long)map & PAGE_MASK));
>          put_page_and_type(pg);
>      }
>  }

On v1 in a reply to Julien you talk of "limiting misuse" by not relaxing
expecations in Arm's backing code, but I wonder what kind of misuse you
think about. Aiui there's no strong need to insist on page aligned input,
and relaxing things there may simplify code elsewhere as well.

Jan



 


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