Re: [PATCH v12 06/22] x86/virt/tdx: Handle SEAMCALL running out of entropy error

[Peter Zijlstra]

On Tue, Jun 27, 2023 at 02:12:36AM +1200, Kai Huang wrote:

>  	cpu = get_cpu();
> -	sret = __seamcall(fn, rcx, rdx, r8, r9, out);
> +
> +	/*
> +	 * Certain SEAMCALL leaf functions may return error due to
> +	 * running out of entropy, in which case the SEAMCALL should
> +	 * be retried.  Handle this in SEAMCALL common function.
> +	 *
> +	 * Mimic rdrand_long() retry behavior.

Yeah, except that doesn't have preemption disabled.. you do.

> +	 */
> +	do {
> +		sret = __seamcall(fn, rcx, rdx, r8, r9, out);
> +	} while (sret == TDX_RND_NO_ENTROPY && --retry);
> +
>  	put_cpu();