linux-kernel - Re: [PATCH v17 8/8] x86/smpboot: Allow parallel bringup for SEV-ES

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Message-ID: <20230328200725.GHZCNI/dHoUMwhsfiC@fat_crate.local>
Date:   Tue, 28 Mar 2023 22:07:25 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Usama Arif <usama.arif@...edance.com>
Cc:     dwmw2@...radead.org, tglx@...utronix.de, kim.phillips@....com,
        brgerst@...il.com, piotrgorski@...hyos.org,
        oleksandr@...alenko.name, arjan@...ux.intel.com, mingo@...hat.com,
        dave.hansen@...ux.intel.com, hpa@...or.com, x86@...nel.org,
        pbonzini@...hat.com, paulmck@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        rcu@...r.kernel.org, mimoja@...oja.de, hewenliang4@...wei.com,
        thomas.lendacky@....com, seanjc@...gle.com, pmenzel@...gen.mpg.de,
        fam.zheng@...edance.com, punit.agrawal@...edance.com,
        simon.evans@...edance.com, liangma@...ngbit.com,
        gpiccoli@...lia.com, David Woodhouse <dwmw@...zon.co.uk>,
        Sabin Rapan <sabrapan@...zon.com>
Subject: Re: [PATCH v17 8/8] x86/smpboot: Allow parallel bringup for SEV-ES

On Tue, Mar 28, 2023 at 08:57:58PM +0100, Usama Arif wrote:
> From: David Woodhouse <dwmw@...zon.co.uk>
> 
> Enable parallel bringup for SEV-ES guests. The APs can't actually
> execute the CPUID instruction directly during early startup, but they
> can make the GHCB call directly instead, just as the VC trap handler
> would do.
> 
> Thanks to Sabin for talking me through the way this works.
> 
> Suggested-by: Sabin Rapan <sabrapan@...zon.com>
> Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
> Signed-off-by: Usama Arif <usama.arif@...edance.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
> ---
>  arch/x86/coco/core.c              |  5 ++++
>  arch/x86/include/asm/coco.h       |  1 +
>  arch/x86/include/asm/sev-common.h |  3 +++
>  arch/x86/include/asm/smp.h        |  5 +++-
>  arch/x86/kernel/head_64.S         | 30 ++++++++++++++++++++++++
>  arch/x86/kernel/smpboot.c         | 39 ++++++++++++++++++++++++++-----
>  6 files changed, 76 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> index 49b44f881484..0bab38efb15a 100644
> --- a/arch/x86/coco/core.c
> +++ b/arch/x86/coco/core.c
> @@ -129,6 +129,11 @@ u64 cc_mkdec(u64 val)
>  }
>  EXPORT_SYMBOL_GPL(cc_mkdec);
>  
> +enum cc_vendor cc_get_vendor(void)
> +{
> +	return vendor;
> +}
> +
>  __init void cc_set_vendor(enum cc_vendor v)
>  {
>  	vendor = v;
> diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h
> index 3d98c3a60d34..0428d9712c96 100644
> --- a/arch/x86/include/asm/coco.h
> +++ b/arch/x86/include/asm/coco.h
> @@ -12,6 +12,7 @@ enum cc_vendor {
>  };
>  
>  void cc_set_vendor(enum cc_vendor v);
> +enum cc_vendor cc_get_vendor(void);
>  void cc_set_mask(u64 mask);
>  
>  #ifdef CONFIG_ARCH_HAS_CC_PLATFORM

You don't need those hunks adding cc_set_vendor() anymore:

https://git.kernel.org/tip/5ae57743f578725a5dadb6f31d7798ee55e6e967

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette