Re: [PATCH] crypto: ccp - Retry SEV INIT command in case of integrity check failure.

[David Rientjes]

On Mon, 21 Oct 2019, Singh, Brijesh wrote:

> >> From: Ashish Kalra <ashish.kalra@xxxxxxx>
> >>
> >> SEV INIT command loads the SEV related persistent data from NVS
> >> and initializes the platform context. The firmware validates the
> >> persistent state. If validation fails, the firmware will reset
> >> the persisent state and return an integrity check failure status.
> >>
> >> At this point, a subsequent INIT command should succeed, so retry
> >> the command. The INIT command retry is only done during driver
> >> initialization.
> >>
> >> Additional enums along with SEV_RET_SECURE_DATA_INVALID are added
> >> to sev_ret_code to maintain continuity and relevance of enum values.
> >>
> >> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> >> ---
> >>   drivers/crypto/ccp/psp-dev.c | 12 ++++++++++++
> >>   include/uapi/linux/psp-sev.h |  3 +++
> >>   2 files changed, 15 insertions(+)
> >>
> >> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> >> index 6b17d179ef8a..f9318d4482f2 100644
> >> --- a/drivers/crypto/ccp/psp-dev.c
> >> +++ b/drivers/crypto/ccp/psp-dev.c
> >> @@ -1064,6 +1064,18 @@ void psp_pci_init(void)
> >>   
> >>   	/* Initialize the platform */
> >>   	rc = sev_platform_init(&error);
> >> +	if (rc && (error == SEV_RET_SECURE_DATA_INVALID)) {
> >> +		/*
> >> +		 * INIT command returned an integrity check failure
> >> +		 * status code, meaning that firmware load and
> >> +		 * validation of SEV related persistent data has
> >> +		 * failed and persistent state has been erased.
> >> +		 * Retrying INIT command here should succeed.
> >> +		 */
> >> +		dev_dbg(sp->dev, "SEV: retrying INIT command");
> >> +		rc = sev_platform_init(&error);
> >> +	}
> >> +
> >>   	if (rc) {
> >>   		dev_err(sp->dev, "SEV: failed to INIT error %#x\n", error);
> >>   		return;
> > 
> > Curious why this isn't done in __sev_platform_init_locked() since
> > sev_platform_init() can be called when loading the kvm module and the same
> > init failure can happen that way.
> > 
> 
> The FW initialization (aka PLATFORM_INIT) is called in the following
> code paths:
> 
> 1. During system boot up
> 
> and
> 
> 2. After the platform reset command is issued
> 
> The patch takes care of #1. Based on the spec, platform reset command
> should erase the persistent data and the PLATFORM_INIT should *not* fail
> with SEV_RET_SECURE_DATA_INVALID error code. So, I am not able to see
> any  strong reason to move the retry code in
> __sev_platform_init_locked().
> 

Hmm, is the sev_platform_init() call in sev_guest_init() intended to do 
SEV_CMD_INIT only after platform reset?  I was under the impression it was 
done in case any previous init failed.