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Date: Thu, 22 Dec 2022 16:31:16 +0100
From: Borislav Petkov <bp@...en8.de>
To: Dionna Glaze <dionnaglaze@...gle.com>,
Thomas Lendacky <Thomas.Lendacky@....com>,
Herbert Xu <herbert@...dor.apana.org.au>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
Peter Gonda <pgonda@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Joerg Roedel <jroedel@...e.de>, Ingo Molnar <mingo@...hat.com>,
Andy Lutomirsky <luto@...nel.org>,
John Allen <john.allen@....com>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v9 1/4] crypto: ccp - Name -1 return value as
SEV_RET_NO_FW_CALL
On Wed, Dec 07, 2022 at 01:02:07AM +0000, Dionna Glaze wrote:
> From: Peter Gonda <pgonda@...gle.com>
>
> The PSP can return a "firmware error" code of -1 in circumstances where
> the PSP is not actually called. To make this protocol unambiguous, the
> value is named SEV_RET_NO_FW_CALL.
>
> Cc: Thomas Lendacky <Thomas.Lendacky@....com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Joerg Roedel <jroedel@...e.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Andy Lutomirsky <luto@...nel.org>
> Cc: John Allen <john.allen@....com>
> Cc: Herbert Xu <herbert@...dor.apana.org.au>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Borislav Petkov <bp@...en8.de>
>
> Signed-off-by: Peter Gonda <pgonda@...gle.com>
> Signed-off-by: Dionna Glaze <dionnaglaze@...gle.com>
> ---
> Documentation/virt/coco/sev-guest.rst | 2 +-
> drivers/crypto/ccp/sev-dev.c | 22 ++++++++++++++--------
> include/uapi/linux/psp-sev.h | 7 +++++++
> 3 files changed, 22 insertions(+), 9 deletions(-)
Looks good, did some minor touch ups ontop, see below.
@Tom: Ack/Rev-by?
@Herbert: ok to carry this through tip?
Thx.
---
From: Peter Gonda <pgonda@...gle.com>
Date: Wed, 7 Dec 2022 01:02:07 +0000
Subject: [PATCH] crypto: 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 has not actually been called. To make this protocol unambiguous,
the name the value SEV_RET_NO_FW_CALL.
[ bp: Massage a bit, get rid of the funky ->init_function local
function pointer. ]
Signed-off-by: Peter Gonda <pgonda@...gle.com>
Signed-off-by: Dionna Glaze <dionnaglaze@...gle.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20221207010210.2563293-2-dionnaglaze@google.com
---
Documentation/virt/coco/sev-guest.rst | 4 ++--
drivers/crypto/ccp/sev-dev.c | 22 ++++++++++++++--------
include/uapi/linux/psp-sev.h | 7 +++++++
3 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst
index bf593e88cfd9..aa3e4c6a1f90 100644
--- a/Documentation/virt/coco/sev-guest.rst
+++ b/Documentation/virt/coco/sev-guest.rst
@@ -40,8 +40,8 @@ along with a description:
The guest ioctl should be issued on a file descriptor of the /dev/sev-guest device.
The ioctl accepts struct snp_user_guest_request. The input and output structure is
specified through the req_data and resp_data field respectively. If the ioctl fails
-to execute due to a firmware error, then fw_err code will be set otherwise the
-fw_err will be set to 0x00000000000000ff.
+to execute due to a firmware error, then fw_err code will be set. Otherwise, fw_err
+will be set to 0x00000000ffffffff, i.e., the lower 32-bits are -1.
The firmware checks that the message sequence counter is one greater than
the guests message sequence counter. If guest driver fails to increment message
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 06fc7156c04f..ac205f78a595 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -440,12 +440,19 @@ static int __sev_init_ex_locked(int *error)
return __sev_do_cmd_locked(SEV_CMD_INIT_EX, &data, error);
}
+static inline int __sev_do_init_locked(int *psp_ret)
+{
+ if (sev_init_ex_buffer)
+ return __sev_init_ex_locked(psp_ret);
+ else
+ return __sev_init_locked(psp_ret);
+}
+
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 (*init_function)(int *error);
+ int rc = 0, psp_ret = SEV_RET_NO_FW_CALL;
if (!psp || !psp->sev_data)
return -ENODEV;
@@ -456,15 +463,12 @@ static int __sev_platform_init_locked(int *error)
return 0;
if (sev_init_ex_buffer) {
- init_function = __sev_init_ex_locked;
rc = sev_read_init_ex_file();
if (rc)
return rc;
- } else {
- init_function = __sev_init_locked;
}
- rc = init_function(&psp_ret);
+ rc = __sev_do_init_locked(&psp_ret);
if (rc && psp_ret == SEV_RET_SECURE_DATA_INVALID) {
/*
* Initialization command returned an integrity check failure
@@ -473,9 +477,11 @@ static int __sev_platform_init_locked(int *error)
* initialization function should succeed by replacing the state
* with a reset state.
*/
- 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);
+ dev_err(sev->dev,
+"SEV: retrying INIT command because of SECURE_DATA_INVALID error. Retrying once to reset PSP SEV state.");
+ rc = __sev_do_init_locked(&psp_ret);
}
+
if (error)
*error = psp_ret;
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 91b4c63d5cbf..f44514653f5f 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.
+ * The SEV API error codes are 16 bits, so the -1 value will not overlap
+ * with possible values from the specification.
+ */
+ SEV_RET_NO_FW_CALL = -1,
SEV_RET_SUCCESS = 0,
SEV_RET_INVALID_PLATFORM_STATE,
SEV_RET_INVALID_GUEST_STATE,
--
2.35.1
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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