Re: [Xen-devel] [PATCH] xen/arm: remove special dom0 case in dump_hyp_walk

[Jürgen Groß <jgross@xxxxxxxx>]

On 15.10.19 05:49, Stefano Stabellini wrote:
> There is no need to have a special dom0 case to convert the pgtable
> virtual address into a physical address. The virt_to_maddr function can
> work both in the dom0 case and the domU case.
>
> This is more than a cleanup: when Xen is loaded at addresses lower than
> 2MB on arm32 phys_offset might not hold the right value and be unable to
> perform a virt to phys conversion properly. Reducing the unnecessary
> usage of phys_offset is a good idea.
>
> Link: https://marc.info/?l=xen-devel&m=157081398022401
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index a6637ce347..b7883cfbab 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -284,10 +284,7 @@ void dump_hyp_walk(vaddr_t addr)
>              "on CPU%d via TTBR 0x%016"PRIx64"\n",
>              addr, smp_processor_id(), ttbr);
>   
> -    if ( smp_processor_id() == 0 )
> -        BUG_ON( (lpae_t *)(unsigned long)(ttbr - phys_offset) != pgtable );
> -    else
> -        BUG_ON( virt_to_maddr(pgtable) != ttbr );
> +    BUG_ON( virt_to_maddr(pgtable) != ttbr );
>       dump_pt_walk(ttbr, addr, HYP_PT_ROOT_LEVEL, 1);
>   }
I can't make a connection between commit message ("special dom0 case")
and the code modification. The special case removed is about cpu 0, not
dom0.


Juergen

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