Re: [PATCH] x86/coco: Require seeding RNG with RDRAND on CoCo systems

[Andi Kleen]

> +	for (i = 0; i < ARRAY_SIZE(rng_seed); i += longs) {
> +		longs = arch_get_random_longs(&rng_seed[i], ARRAY_SIZE(rng_seed) - i);
> +
> +		/*
> +		 * A zero return value means that the guest is under attack,
> +		 * the hardware is broken, or some other mishap has occurred
> +		 * that means the RNG cannot be properly rng_seeded, which also
> +		 * likely means most crypto inside of the CoCo instance will be
> +		 * broken, defeating the purpose of CoCo in the first place. So
> +		 * just panic here because it's absolutely unsafe to continue
> +		 * executing.
> +		 */
> +		BUG_ON(longs == 0);

BUG_ON doesn't necessarily panic. If you want panic, use panic.

-Andi