linux-kernel - Re: [PATCH] powerpc/pseries: detect secure and trusted boot state of the system.

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Date:   Tue, 07 Jul 2020 12:06:32 +1000
From:   Daniel Axtens <dja@...ens.net>
To:     Nayna Jain <nayna@...ux.ibm.com>, linuxppc-dev@...abs.org
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Mimi Zohar <zohar@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH] powerpc/pseries: detect secure and trusted boot state of the system.

Thanks Nayna!

I'm hoping to get better public documentation for this soon as it's not
documented in a public PAPR yet.

Until then:

The values of ibm,secure-boot under PowerVM are:

 0 - disabled
 
 1 - audit mode only. This patch ignores this value for Linux, which I
     think is the appropriate thing to do.

 2 - enabled and enforcing

 3-9 - enabled, OS-defined behaviour. In this patch we map all these
       values to enabled and enforcing. Again I think this is the
       appropriate thing to do.

ibm,trusted-boot isn't published by a current PowerVM LPAR but will be
published in future. (Currently, trusted boot state is inferred by the
presence or absense of a vTPM.) It's simply 1 = enabled, 0 = disabled.

As for this patch specifically, with the very small nits below,

Reviewed-by: Daniel Axtens <dja@...ens.net>

> -	node = get_ppc_fw_sb_node();
> -	enabled = of_property_read_bool(node, "os-secureboot-enforcing");
> +	if (machine_is(powernv)) {
> +		node = get_ppc_fw_sb_node();
> +		enabled =
> +		    of_property_read_bool(node, "os-secureboot-enforcing");
> +		of_node_put(node);
> +	}
>  
> -	of_node_put(node);
> +	if (machine_is(pseries)) {
Maybe this should be an else if?

> +		secureboot = of_get_property(of_root, "ibm,secure-boot", NULL);
> +		if (secureboot)
> +			enabled = (*secureboot > 1) ? true : false;
> +	}
>  
>  	pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
>  
> @@ -38,11 +48,20 @@ bool is_ppc_trustedboot_enabled(void)
>  {
>  	struct device_node *node;
>  	bool enabled = false;
> +	const u32 *trustedboot;
>  
> -	node = get_ppc_fw_sb_node();
> -	enabled = of_property_read_bool(node, "trusted-enabled");
> +	if (machine_is(powernv)) {
> +		node = get_ppc_fw_sb_node();
> +		enabled = of_property_read_bool(node, "trusted-enabled");
> +		of_node_put(node);
> +	}
>  
> -	of_node_put(node);
> +	if (machine_is(pseries)) {
Likewise.
> +		trustedboot =
> +		    of_get_property(of_root, "ibm,trusted-boot", NULL);
> +		if (trustedboot)
> +			enabled = (*trustedboot > 0) ? true : false;

Regards,
Daniel