Re: [Xen-devel] [PATCH 2/2] arm/traps: fix bug in dump_guest_s1_walk handling of level 2 page tables

[Julien Grall <julien.grall@xxxxxxx>]

On 19/07/16 18:15, Jonathan Daugherty wrote:
> dump_guest_s1_walk intends to walk to level 2 page table entries but
> was failing to do so because of a check that caused level 2 page table
> descriptors to be ignored. This change fixes the check so that level 2
> page table walks occur as intended by ignoring descriptors unless their
> low two bits match the expected sequence [0,1].
>
> For more information, see the ARMv7-A ARM, section B3.5.
NIT: Could you specify the version of the spec (i.e something similar to 
ARM DDI 0406C.c)?
Also, to be precise the section would be B3.5.1.

> Signed-off-by: Jonathan Daugherty <jtd@xxxxxxxxxx>
Reviewed-by: Julien Grall <julien.grall@xxxxxxx>

Regards,

> ---
>  xen/arch/arm/traps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 0c10c4d..dfb1949 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2350,7 +2350,7 @@ void dump_guest_s1_walk(struct domain *d, vaddr_t addr)
>      printk("1ST[0x%"PRIx32"] (0x%"PRIpaddr") = 0x%08"PRIx32"\n",
>             offset, pfn_to_paddr(mfn_x(mfn)), first[offset]);
>      if ( !(first[offset] & 0x1) ||
> -         !(first[offset] & 0x2) )
> +          (first[offset] & 0x2) )
>          goto done;
>
>      mfn = p2m_lookup(d, _gfn(paddr_to_pfn(first[offset])), NULL);
--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel