Re: [PATCH v4 8/9] xen/arm: Implement hypercall for dirty page tracing

[Julien Grall <julien.grall@linaro.org>]

On 10/08/2013 04:36 PM, Eugene Fedotov wrote:
> If we move necessary checking into handle_page_fault routine, so the
> resulting patch for traps.c will look more simple:
> 
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -1313,6 +1313,8 @@ static void do_trap_data_abort_guest(struct
> cpu_user_regs *regs,
>      const char *msg;
>      int rc, level = -1;
>      mmio_info_t info;
> +    int page_fault = ( (dabt.dfsc & FSC_MASK) ==
> +                          (FSC_FLT_PERM | FSC_3D_LEVEL) && dabt.write );
> 
>      if ( !check_conditional_instr(regs, hsr) )
>      {
> @@ -1334,6 +1336,13 @@ static void do_trap_data_abort_guest(struct
> cpu_user_regs *regs,
>      if ( rc == -EFAULT )
>          goto bad_data_abort;
> 
> +    /* domU page fault handling for guest live migration */
> +    /* dabt.valid can be 0 here */
> +    if ( page_fault && handle_page_fault(current->domain, info.gpa) )
> +    {
> +        /* Do not modify pc after page fault to repeat memory operation */
> +        return;
> +    }
>      /* XXX: Decode the instruction if ISS is not valid */
>      if ( !dabt.valid )
>          goto bad_data_abort;
> 
> Will it be acceptable, or you think "else" statement looks more better?

I'm fine with this solution.

Cheers,

-- 
Julien Grall