Re: [Xen-devel] [PATCH 2/2] arm: kill a guest which uses hvc with an immediate operand != XEN_HYPERCALL_TAG

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 23 Jul 2012, Ian Campbell wrote:
> At best these guests are confused/broken and at worse they are malicious.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  xen/arch/arm/traps.c |    6 +-----
>  1 files changed, 1 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 52ab943..50b62c0 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -472,11 +472,7 @@ static void do_trap_hypercall(struct cpu_user_regs 
> *regs, unsigned long iss)
>      arm_hypercall_fn_t call = NULL;
>  
>      if ( iss != XEN_HYPERCALL_TAG )
> -    {
> -        printk("%s %d: received an alien hypercall iss=%lx\n", __func__ ,
> -                __LINE__ , iss);
> -        regs->r0 = -EINVAL;
> -    }
> +        domain_crash_synchronous();
>  
>      if ( regs->r12 > ARRAY_SIZE(arm_hypercall_table) )
>      {

Are we sure that this is actually necessary?
I think that the old behaviour of returning -EINVAL is sufficient.

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