linux-kernel - Re: [PATCH] crypto: ccp: Improve sev_platform

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Date:   Sun, 8 Jan 2023 19:50:56 +0000
From:   Jarkko Sakkinen <jarkko@...fian.com>
To:     David Rientjes <rientjes@...gle.com>
Cc:     linux-crypto@...r.kernel.org,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] crypto: ccp: Improve sev_platform_init() error messages

On Sun, Jan 01, 2023 at 07:18:30PM -0800, David Rientjes wrote:
> On Sat, 31 Dec 2022, Jarkko Sakkinen wrote:
> 
> > The following functions end up calling sev_platform_init() or
> > __sev_platform_init_locked():
> > 
> > * sev_guest_init()
> > * sev_ioctl_do_pek_csr
> > * sev_ioctl_do_pdh_export()
> > * sev_ioctl_do_pek_import()
> > * sev_ioctl_do_pek_pdh_gen()
> > * sev_pci_init()
> > 
> > However, only sev_pci_init() prints out the failed command error code, and
> > even there the error message does not specify, SEV which command failed.
> > 
> > Address this by printing out the SEV command errors inside
> > __sev_platform_init_locked(), and differentiate between DF_FLUSH, INIT and
> > INIT_EX commands.
> > 
> > This extra information is particularly useful if firmware loading and/or
> > initialization is going to be made more robust, e.g. by allowing
> > firmware loading to be postponed.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> > ---
> >  drivers/crypto/ccp/sev-dev.c | 19 ++++++++++++-------
> >  1 file changed, 12 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> > index 5350eacaba3a..ac7385c12091 100644
> > --- a/drivers/crypto/ccp/sev-dev.c
> > +++ b/drivers/crypto/ccp/sev-dev.c
> > @@ -963,6 +963,7 @@ static int __sev_init_ex_locked(int *error)
> >  
> >  static int __sev_platform_init_locked(int *error)
> >  {
> > +	const char *cmd = sev_init_ex_buffer ? "SEV_CMD_INIT_EX" : "SEV_CMD_INIT";
> >  	struct psp_device *psp = psp_master;
> >  	struct sev_device *sev;
> >  	int rc = 0, psp_ret = -1;
> 
> I think this can just be handled directly in the dev_err() since it's only 
> used once.

Ack.

> > @@ -1008,18 +1009,23 @@ static int __sev_platform_init_locked(int *error)
> >  	if (error)
> >  		*error = psp_ret;
> >  
> > -	if (rc)
> > +	if (rc) {
> > +		dev_err(sev->dev, "SEV: %s failed error %#x", cmd, psp_ret);
> >  		return rc;
> > +	}
> >  
> >  	sev->state = SEV_STATE_INIT;
> >  
> >  	/* Prepare for first SEV guest launch after INIT */
> >  	wbinvd_on_all_cpus();
> > -	rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, error);
> > -	if (rc)
> > -		return rc;
> > +	rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, &psp_ret);
> > +	if (error)
> > +		*error = psp_ret;
> >  
> > -	dev_dbg(sev->dev, "SEV firmware initialized\n");
> 
> Any reason to remove this dbg line?  I assume the following dev_info() 
> line is deemed sufficient?

Yes, but agreed that it is not in the scope of the patch so I'll remove
it from the next version.

> 
> > +	if (rc) {
> > +		dev_err(sev->dev, "SEV: SEV_CMD_DF_FLUSH failed error %#x", psp_ret);
> > +		return rc;
> > +	}
> >  
> >  	dev_info(sev->dev, "SEV API:%d.%d build:%d\n", sev->api_major,
> >  		 sev->api_minor, sev->build);
> > @@ -2354,8 +2360,7 @@ void sev_pci_init(void)
> >  	/* Initialize the platform */
> >  	rc = sev_platform_init(&error);
> >  	if (rc)
> > -		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
> > -			error, rc);
> > +		dev_err(sev->dev, "SEV: failed to INIT rc %d\n", rc);
> >  
> >  skip_legacy:
> >  	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?

Thank you for the feedback.

BR, Jarkko