linux-kernel - Re: [PATCH v4] crypto: ccp: Sanitize sev_platform

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Date:   Tue, 10 Jan 2023 15:54:48 +0000
From:   Jarkko Sakkinen <jarkko@...fian.com>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Brijesh Singh <brijesh.singh@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER - SE..." 
        <linux-crypto@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] crypto: ccp: Sanitize sev_platform_init() error
 messages

On Tue, Jan 10, 2023 at 08:41:33AM -0600, Tom Lendacky wrote:
> On 1/9/23 21:35, 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 which SEV 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.  As a side-effect, @error can be removed from the
> > parameter list.
> > 
> > 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.
> > ---
> > v4:
> > * Sorry, v3 was malformed. Here's a proper patch.
> > 
> > v3:
> > * Address Tom Lendacky's feedback:
> >    https://lore.kernel.org/kvm/8bf6f179-eee7-fd86-7892-cdcd76e0762a@amd.com/
> > 
> > v2:
> > * Address David Rientjes's feedback:
> >    https://lore.kernel.org/all/6a16bbe4-4281-fb28-78c4-4ec44c8aa679@google.com/
> > * Remove @error.
> > * Remove "SEV_" prefix: it is obvious from context so no need to make klog
> >    line longer.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> > ---
> >   drivers/crypto/ccp/sev-dev.c | 17 ++++++++++-------
> >   1 file changed, 10 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> > index 06fc7156c04f..bdc43e75c78b 100644
> > --- a/drivers/crypto/ccp/sev-dev.c
> > +++ b/drivers/crypto/ccp/sev-dev.c
> > @@ -476,19 +476,23 @@ static int __sev_platform_init_locked(int *error)
> >   		dev_err(sev->dev, "SEV: retrying INIT command because of SECURE_DATA_INVALID error. Retrying once to reset PSP SEV state.");
> >   		rc = init_function(&psp_ret);
> >   	}
> > -	if (error)
> > +	if (rc) {
> > +		dev_err(sev->dev, "SEV: %s failed error %#x",
> > +			sev_init_ex_buffer ? "CMD_INIT_EX" : "CMD_INIT", psp_ret);
> >   		*error = psp_ret;
> 
> If I'm not mistaken, error can be NULL, that's why the "if (error)" was
> present. So that should be kept and even filled in on success. So please
> leave it the way it was and just add the message to the "if (rc)" section.

Ah, right thanks, will do.

> > -
> > -	if (rc)
> >   		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)
> > +	rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, &psp_ret);
> 
> Same here, add:
> 
> 	if (error)
> 		*error = psp_ret;
> > +	if (rc) {
> > +		dev_err(sev->dev, "SEV: CMD_DF_FLUSH failed error %#x", psp_ret);
> > +		*error = psp_ret;
> >   		return rc;
> > +	}
> >   	dev_dbg(sev->dev, "SEV firmware initialized\n");
> > @@ -1337,8 +1341,7 @@ 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);
> >   	return;

BR, Jarkko