linux-kernel - Re: [PATCH v6 21/22] x86/boot: Move startup code out of _

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Message-ID: <CAMj1kXGY7-ZmQbUnw-KtMq6HG-o9xUNmb7KMHAzdBBbWBmGo=g@mail.gmail.com>
Date: Thu, 28 Aug 2025 08:50:15 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: Borislav Petkov <bp@...en8.de>, Ard Biesheuvel <ardb+git@...gle.com>, linux-kernel@...r.kernel.org, 
	linux-efi@...r.kernel.org, x86@...nel.org, Ingo Molnar <mingo@...nel.org>, 
	Kevin Loughlin <kevinloughlin@...gle.com>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Nikunj A Dadhania <nikunj@....com>, 
	Neeraj Upadhyay <Neeraj.Upadhyay@....com>
Subject: Re: [PATCH v6 21/22] x86/boot: Move startup code out of __head section

On Thu, 14 Aug 2025 at 19:17, Tom Lendacky <thomas.lendacky@....com> wrote:
>
> On 8/11/25 14:03, Borislav Petkov wrote:
> > On Mon, Aug 11, 2025 at 01:05:42PM -0500, Tom Lendacky wrote:
> >> Yes, that works. Or just get rid of snp_abort() and call
> >> sev_es_terminate() directly. Secure AVIC could even use an
> >> SEV_TERM_SET_LINUX specific code instead of the generic failure code.
> >
> > I *love* deleting code. Here's something to start the debate:
> >
> > ---
> > diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/sev-startup.c
> > index 7a8128dc076e..19b23e6d2dbe 100644
> > --- a/arch/x86/boot/startup/sev-startup.c
> > +++ b/arch/x86/boot/startup/sev-startup.c
> > @@ -135,7 +135,7 @@ static struct cc_blob_sev_info *__init find_cc_blob(struct boot_params *bp)
> >
> >  found_cc_info:
> >       if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
> > -             snp_abort();
> > +             sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
> >
> >       return cc_info;
> >  }
> > @@ -209,8 +209,3 @@ bool __init snp_init(struct boot_params *bp)
> >
> >       return true;
> >  }
> > -
> > -void __init __noreturn snp_abort(void)
> > -{
> > -     sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
> > -}
> > diff --git a/arch/x86/boot/startup/sme.c b/arch/x86/boot/startup/sme.c
> > index 39e7e9d18974..e389b39fa2a9 100644
> > --- a/arch/x86/boot/startup/sme.c
> > +++ b/arch/x86/boot/startup/sme.c
> > @@ -531,7 +531,7 @@ void __init sme_enable(struct boot_params *bp)
> >        * enablement abort the guest.
> >        */
> >       if (snp_en ^ !!(msr & MSR_AMD64_SEV_SNP_ENABLED))
> > -             snp_abort();
> > +             sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
> >
> >       /* Check if memory encryption is enabled */
> >       if (feature_mask == AMD_SME_BIT) {
> > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> > index 0020d77a0800..01a6e4dbe423 100644
> > --- a/arch/x86/include/asm/sev-common.h
> > +++ b/arch/x86/include/asm/sev-common.h
> > @@ -208,6 +208,7 @@ struct snp_psc_desc {
> >  #define GHCB_TERM_SVSM_CAA           9       /* SVSM is present but CAA is not page aligned */
> >  #define GHCB_TERM_SECURE_TSC         10      /* Secure TSC initialization failed */
> >  #define GHCB_TERM_SVSM_CA_REMAP_FAIL 11      /* SVSM is present but CA could not be remapped */
> > +#define GHCB_TERM_SAVIC_FAIL         12      /* Secure AVIC-specific failure */
>
> We can get specific if desired, e.g., GHCB_TERM_SAVIC_NO_X2APIC
>

I'll fold this in for the next revision, and we can take it from there.