linux-kernel - Re: [Part2 PATCH v5.1 12.6/31] crypto: ccp: Implement SEV_PDH

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Date:   Thu, 12 Oct 2017 20:48:10 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Gary Hook <gary.hook@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-crypto@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Part2 PATCH v5.1 12.6/31] crypto: ccp: Implement SEV_PDH_GEN
 ioctl command

On Fri, Oct 06, 2017 at 08:06:04PM -0500, Brijesh Singh wrote:
> The SEV_PDH_GEN command is used to re-generate the Platform
> Diffie-Hellman (PDH) key. The command is defined in SEV spec section
> 5.9.
> 
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: "Radim Krčmář" <rkrcmar@...hat.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: Gary Hook <gary.hook@....com>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: linux-crypto@...r.kernel.org
> Cc: kvm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  drivers/crypto/ccp/psp-dev.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> index 03d7bd03ad58..28efb7a9245a 100644
> --- a/drivers/crypto/ccp/psp-dev.c
> +++ b/drivers/crypto/ccp/psp-dev.c
> @@ -271,6 +271,34 @@ static int sev_ioctl_pek_gen(struct sev_issue_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_ioctl_pdh_gen(struct sev_issue_cmd *argp)
> +{
> +	int ret, state, do_shutdown = 0;
> +
> +	/*
> +	 * PDH_GEN command can be issued when platform is in INIT or WORKING
> +	 * state. If we are in UNINIT state then transition in INIT state
> +	 * before issuing the command.
> +	 */
> +	ret = sev_platform_get_state(&state, &argp->error);
> +	if (ret)
> +		return ret;
> +

Why isn't this function doing:

        if (state == SEV_STATE_WORKING) {
                return -EBUSY;

like the PEK_GEN one?

Because if so, you can convert it and the PEK_GEN one into a single
function doing the work and wrappers handing in the command to avoid the
code duplication.

> +	if (state == SEV_STATE_UNINIT) {
> +		ret = sev_firmware_init(&argp->error);
> +		if (ret)
> +			return ret;
> +		do_shutdown = 1;
> +	}
> +
> +	ret = sev_handle_cmd(SEV_CMD_PDH_GEN, 0, &argp->error);
> +
> +	if (do_shutdown)
> +		sev_handle_cmd(SEV_CMD_SHUTDOWN, 0, NULL);
> +
> +	return ret;
> +}
> +
>  static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
>  {
>  	void __user *argp = (void __user *)arg;
> @@ -300,6 +328,10 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
>  		ret = sev_ioctl_pek_gen(&input);
>  		break;
>  	}
> +	case SEV_PDH_GEN: {
> +		ret = sev_ioctl_pdh_gen(&input);
> +		break;
> +	}

And those curly braces can go, as before.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--