2019-10-18 22:22:18

by Kalra, Ashish

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

From: Ashish Kalra <[email protected]>

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 <[email protected]>
---
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;
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 8654b2442f6a..a8537f4e5e08 100644
--- a/include/uapi/linux/psp-sev.h
+++ b/include/uapi/linux/psp-sev.h
@@ -58,6 +58,9 @@ typedef enum {
SEV_RET_HWSEV_RET_PLATFORM,
SEV_RET_HWSEV_RET_UNSAFE,
SEV_RET_UNSUPPORTED,
+ SEV_RET_INVALID_PARAM,
+ SEV_RET_RESOURCE_LIMIT,
+ SEV_RET_SECURE_DATA_INVALID,
SEV_RET_MAX,
} sev_ret_code;

--
2.17.1

2019-10-21 18:17:21

by Brijesh Singh

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

On 10/19/19 3:59 AM, David Rientjes wrote:
> On Thu, 17 Oct 2019, Kalra, Ashish wrote:
>
>> From: Ashish Kalra <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> 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().

thanks