linux-kernel - Re: [PATCH v3 74/75] x86/sev-es: Handle NMI State

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Date:   Wed, 3 Jun 2020 11:59:23 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 74/75] x86/sev-es: Handle NMI State

On Tue, Apr 28, 2020 at 05:17:24PM +0200, Joerg Roedel wrote:
> diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
> index 27d1016ec840..8898002e5600 100644
> --- a/arch/x86/kernel/nmi.c
> +++ b/arch/x86/kernel/nmi.c
> @@ -511,6 +511,13 @@ NOKPROBE_SYMBOL(is_debug_stack);
>  dotraplinkage notrace void
>  do_nmi(struct pt_regs *regs, long error_code)
>  {
> +	/*
> +	 * Re-enable NMIs right here when running as an SEV-ES guest. This might
> +	 * cause nested NMIs, but those can be handled safely.
> +	 */
> +	if (sev_es_active())
> +		sev_es_nmi_complete();

Pls move the comment and the sev_es_active() check into
the sev_es_nmi_complete() function.

-- 
Regards/Gruss,
    Boris.

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