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Date:   Fri, 5 May 2023 19:54:44 +0200
From:   Simon Horman <horms@kernel.org>
To:     Ross Philipson <ross.philipson@oracle.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
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Subject: Re: [PATCH v6 09/14] x86: Secure Launch SMP bringup support
Message-ID: <ZFVC5Fv0wO0Awt0N@kernel.org>
References: <20230504145023.835096-1-ross.philipson@oracle.com>
 <20230504145023.835096-10-ross.philipson@oracle.com>
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On Thu, May 04, 2023 at 02:50:18PM +0000, Ross Philipson wrote:
> On Intel, the APs are left in a well documented state after TXT performs
> the late launch. Specifically they cannot have #INIT asserted on them so
> a standard startup via INIT/SIPI/SIPI cannot be performed. Instead the
> early SL stub code parked the APs in a pause/jmp loop waiting for an NMI.
> The modified SMP boot code is called for the Secure Launch case. The
> jump address for the RM piggy entry point is fixed up in the jump where
> the APs are waiting and an NMI IPI is sent to the AP. The AP vectors to
> the Secure Launch entry point in the RM piggy which mimics what the real
> mode code would do then jumps to the standard RM piggy protected mode
> entry point.
> 
> Signed-off-by: Ross Philipson <ross.philipson@oracle.com>

Hi Ross,

just one minor nit on this one.

>  /*
>   * NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
>   * (ie clustered apic addressing mode), this is a LOGICAL apic ID.
> @@ -1132,6 +1210,13 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
>  	cpumask_clear_cpu(cpu, cpu_initialized_mask);
>  	smp_mb();
>  
> +	/* With Intel TXT, the AP startup is totally different */
> +	if ((slaunch_get_flags() & (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT)) ==

nit: spaces around '|'

> +	   (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT)) {
> +		boot_error = slaunch_wakeup_cpu_from_txt(cpu, apicid);
> +		goto txt_wake;
> +	}