linux-kernel - Re: [PATCH Part2 v6 13/49] crypto:ccp: Provide APIs to issue SEV-SNP commands

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Date:   Sat, 1 Oct 2022 22:17:44 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        jroedel@...e.de, thomas.lendacky@....com, hpa@...or.com,
        ardb@...nel.org, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, jmattson@...gle.com, luto@...nel.org,
        dave.hansen@...ux.intel.com, slp@...hat.com, pgonda@...gle.com,
        peterz@...radead.org, srinivas.pandruvada@...ux.intel.com,
        rientjes@...gle.com, dovmurik@...ux.ibm.com, tobin@....com,
        michael.roth@....com, vbabka@...e.cz, kirill@...temov.name,
        ak@...ux.intel.com, tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
        dgilbert@...hat.com, jarkko@...nel.org
Subject: Re: [PATCH Part2 v6 13/49] crypto:ccp: Provide APIs to issue SEV-SNP
 commands

On Mon, Jun 20, 2022 at 11:04:45PM +0000, Ashish Kalra wrote:
> From: Brijesh Singh <brijesh.singh@....com>
> 
> Provide the APIs for the hypervisor to manage an SEV-SNP guest. The
> commands for SEV-SNP is defined in the SEV-SNP firmware specification.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  drivers/crypto/ccp/sev-dev.c | 24 ++++++++++++
>  include/linux/psp-sev.h      | 73 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 97 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index f1173221d0b9..35d76333e120 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1205,6 +1205,30 @@ int sev_guest_df_flush(int *error)
>  }
>  EXPORT_SYMBOL_GPL(sev_guest_df_flush);
>  
> +int snp_guest_decommission(struct sev_data_snp_decommission *data, int *error)
> +{
> +	return sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, data, error);
> +}
> +EXPORT_SYMBOL_GPL(snp_guest_decommission);
> +
> +int snp_guest_df_flush(int *error)
> +{
> +	return sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, error);
> +}
> +EXPORT_SYMBOL_GPL(snp_guest_df_flush);
> +
> +int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data, int *error)
> +{
> +	return sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, data, error);
> +}
> +EXPORT_SYMBOL_GPL(snp_guest_page_reclaim);
> +
> +int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error)
> +{
> +	return sev_do_cmd(SEV_CMD_SNP_DBG_DECRYPT, data, error);
> +}
> +EXPORT_SYMBOL_GPL(snp_guest_dbg_decrypt);

So this mindless repetition is getting annoying. I see ~70 SEV commands.
Adding ~70 functions which parrot all the same call to sev_do_cmd() is
just insane.

I think you should simply export sev_do_cmd() and call it instead.

Yes, when it turns out that a command and the preparation to issue it
before it starts repeating pretty often, you could do a helper. But
adding those silly wrappers doesn't bring anything besides confusion and
code bloat.

Thx.

-- 
Regards/Gruss,
    Boris.

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