linux-kernel - Re: [PATCH v8 06/40] x86/sev: Check SEV-SNP features support

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Message-ID: <YbuM+WgDr+wL+jsu@dt>
Date:   Thu, 16 Dec 2021 13:01:13 -0600
From:   Venu Busireddy <venu.busireddy@...cle.com>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v8 06/40] x86/sev: Check SEV-SNP features support

On 2021-12-10 09:42:58 -0600, Brijesh Singh wrote:
> Version 2 of the GHCB specification added the advertisement of features
> that are supported by the hypervisor. If hypervisor supports the SEV-SNP
> then it must set the SEV-SNP features bit to indicate that the base
> SEV-SNP is supported.
> 
> Check the SEV-SNP feature while establishing the GHCB, if failed,
> terminate the guest.
> 
> Version 2 of GHCB specification adds several new NAEs, most of them are
> optional except the hypervisor feature. Now that hypervisor feature NAE
> is implemented, so bump the GHCB maximum support protocol version.
> 
> While at it, move the GHCB protocol negotitation check from VC exception
> handler to sev_enable() so that all feature detection happens before
> the first VC exception.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/boot/compressed/sev.c    | 21 ++++++++++++++++-----
>  arch/x86/include/asm/sev-common.h |  6 ++++++
>  arch/x86/include/asm/sev.h        |  2 +-
>  arch/x86/include/uapi/asm/svm.h   |  2 ++
>  arch/x86/kernel/sev-shared.c      | 20 ++++++++++++++++++++
>  arch/x86/kernel/sev.c             | 16 ++++++++++++++++
>  6 files changed, 61 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
> index 0b6cc6402ac1..a0708f359a46 100644
> --- a/arch/x86/boot/compressed/sev.c
> +++ b/arch/x86/boot/compressed/sev.c
> @@ -119,11 +119,8 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
>  /* Include code for early handlers */
>  #include "../../kernel/sev-shared.c"
>  
> -static bool early_setup_sev_es(void)
> +static bool early_setup_ghcb(void)
>  {
> -	if (!sev_es_negotiate_protocol())
> -		sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_PROT_UNSUPPORTED);

Should the name sev_es_terminate() be changed to a more generic
name, as we are simply terminating the guest, not SEV or ES as the
name implies?

Other than that...

Reviewed-by: Venu Busireddy <venu.busireddy@...cle.com>