Re: [Xen-devel] [PATCH v2 16/19] xen/arm: Introduce a helper to synchronize SError

[Julien Grall <julien.grall@xxxxxxx>]

Hi Wei,

On 30/03/17 10:13, Wei Chen wrote:
> +void synchronize_serror(void)
Sorry for been late in the party. Looking at the way you use the 
function, you execute depending on the behavior chosen by the user when 
an SErrors happen. This behavior will not change at runtime, so always 
checking the option chosen in the hot path does not sound very efficient.
I would recommend to look at ALTERNATIVE and streamline (dsb sy, isb). I.e

ALTERNATIVE("dsb sy; isb", "nop; nop", ...) or the invert depending of 
the place.
> +{
> +    /* Synchronize against in-flight ld/st. */
> +    dsb(sy);
> +
> +    /* A single instruction exception window */
> +    isb();
> +}
> +
Cheers,

--
Julien Grall

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