2022-10-25 00:28:50

by Dionna Amalie Glaze

Subject: [PATCH v4 1/4] ccp: Name -1 return value as SEV_RET_NO_FW_CALL

The PSP can return a "firmware error" code of -1 in circumstances where
the PSP is not actually called. To make this protocol unambiguous, we
add a constant naming the return value.

From: Peter Gonda <[email protected]>
Cc: Thomas Lendacky <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Andy Lutomirsky <[email protected]>

Signed-off-by: Dionna Glaze <[email protected]>
---
drivers/crypto/ccp/sev-dev.c | 2 +-
include/uapi/linux/psp-sev.h | 7 +++++++
2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 06fc7156c04f..97eb3544ab36 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -444,7 +444,7 @@ static int __sev_platform_init_locked(int *error)
{
struct psp_device *psp = psp_master;
struct sev_device *sev;
- int rc = 0, psp_ret = -1;
+ int rc = 0, psp_ret = SEV_RET_NO_FW_CALL;
int (*init_function)(int *error);

if (!psp || !psp->sev_data)
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 91b4c63d5cbf..fb61e083d42e 100644
--- a/include/uapi/linux/psp-sev.h
+++ b/include/uapi/linux/psp-sev.h
@@ -36,6 +36,13 @@ enum {
* SEV Firmware status code
*/
typedef enum {
+ /*
+ * This error code is not in the SEV spec but is added to convey that
+ * there was an error that prevented the SEV Firmware from being called.
+ * This is (u32)-1 since the firmware error code part of EXIT_INFO_2 is
+ * the lower 32 bits.
+ */
+ SEV_RET_NO_FW_CALL = 0xffffffff,
SEV_RET_SUCCESS = 0,
SEV_RET_INVALID_PLATFORM_STATE,
SEV_RET_INVALID_GUEST_STATE,
--
2.38.0.135.g90850a2211-goog

2022-10-28 14:44:16

by Tom Lendacky

Subject: Re: [PATCH v4 1/4] ccp: Name -1 return value as SEV_RET_NO_FW_CALL

On 10/24/22 17:46, Dionna Glaze wrote:
> The PSP can return a "firmware error" code of -1 in circumstances where
> the PSP is not actually called. To make this protocol unambiguous, we
> add a constant naming the return value.
>
> From: Peter Gonda <[email protected]>
> Cc: Thomas Lendacky <[email protected]>
> Cc: Paolo Bonzini <[email protected]>
> Cc: Joerg Roedel <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Andy Lutomirsky <[email protected]>
>
> Signed-off-by: Dionna Glaze <[email protected]>

Just one minor comment below, otherwise...

Reviewed-by: Tom Lendacky <[email protected]>

> ---
> drivers/crypto/ccp/sev-dev.c | 2 +-
> include/uapi/linux/psp-sev.h | 7 +++++++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 06fc7156c04f..97eb3544ab36 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -444,7 +444,7 @@ static int __sev_platform_init_locked(int *error)
> {
> struct psp_device *psp = psp_master;
> struct sev_device *sev;
> - int rc = 0, psp_ret = -1;
> + int rc = 0, psp_ret = SEV_RET_NO_FW_CALL;
> int (*init_function)(int *error);
>
> if (!psp || !psp->sev_data)
> diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
> index 91b4c63d5cbf..fb61e083d42e 100644
> --- a/include/uapi/linux/psp-sev.h
> +++ b/include/uapi/linux/psp-sev.h
> @@ -36,6 +36,13 @@ enum {
> * SEV Firmware status code
> */
> typedef enum {
> + /*
> + * This error code is not in the SEV spec but is added to convey that
> + * there was an error that prevented the SEV Firmware from being called.
> + * This is (u32)-1 since the firmware error code part of EXIT_INFO_2 is
> + * the lower 32 bits.

These codes are used for /dev/sev access on the HV side, too, where
EXIT_INFO_2 doesn't exist. I would change this to something like:

This is (u32)-1 since the firwmare error code is represented as a 32-bit
integer.

Thanks,
Tom

> + */
> + SEV_RET_NO_FW_CALL = 0xffffffff,
> SEV_RET_SUCCESS = 0,
> SEV_RET_INVALID_PLATFORM_STATE,
> SEV_RET_INVALID_GUEST_STATE,