* [PATCH -v2 01/11] crypto: ccp - Name -1 return value as SEV_RET_NO_FW_CALL
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 02/11] virt/coco/sev-guest: Check SEV_SNP attribute at probe time Borislav Petkov
` (9 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: stable, Dionna Glaze, Joerg Roedel, Michael Roth,
Nikunj A Dadhania, Peter Gonda, Tom Lendacky, linux-coco, x86
From: Peter Gonda <pgonda@google.com>
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,
name the value SEV_RET_NO_FW_CALL.
[ bp: Massage a bit. ]
Signed-off-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
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 | 8 +++++---
include/uapi/linux/psp-sev.h | 7 +++++++
3 files changed, 14 insertions(+), 5 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..f60bb73edfda 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -442,10 +442,10 @@ static int __sev_init_ex_locked(int *error)
static int __sev_platform_init_locked(int *error)
{
+ int rc = 0, psp_ret = SEV_RET_NO_FW_CALL;
struct psp_device *psp = psp_master;
- struct sev_device *sev;
- int rc = 0, psp_ret = -1;
int (*init_function)(int *error);
+ struct sev_device *sev;
if (!psp || !psp->sev_data)
return -ENODEV;
@@ -473,9 +473,11 @@ 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.");
+ 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)
*error = psp_ret;
diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
index 91b4c63d5cbf..1c9da485318f 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. Its purpose is 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
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 02/11] virt/coco/sev-guest: Check SEV_SNP attribute at probe time
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 01/11] crypto: ccp - Name -1 return value as SEV_RET_NO_FW_CALL Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 03/11] virt/coco/sev-guest: Simplify extended guest request handling Borislav Petkov
` (8 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
No need to check it on every ioctl. And yes, this is a common SEV driver
but it does only SNP-specific operations currently. This can be
revisited later, when more use cases appear.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
arch/x86/kernel/sev.c | 3 ---
drivers/virt/coco/sev-guest/sev-guest.c | 3 +++
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 679026a640ef..c644c34372e8 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2183,9 +2183,6 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
struct ghcb *ghcb;
int ret;
- if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
- return -ENODEV;
-
if (!fw_err)
return -EINVAL;
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 4ec4174e05a3..edaf6031c6d9 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -689,6 +689,9 @@ static int __init sev_guest_probe(struct platform_device *pdev)
void __iomem *mapping;
int ret;
+ if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
+ return -ENODEV;
+
if (!dev->platform_data)
return -ENODEV;
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 03/11] virt/coco/sev-guest: Simplify extended guest request handling
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 01/11] crypto: ccp - Name -1 return value as SEV_RET_NO_FW_CALL Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 02/11] virt/coco/sev-guest: Check SEV_SNP attribute at probe time Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 04/11] virt/coco/sev-guest: Remove the disable_vmpck label in handle_guest_request() Borislav Petkov
` (7 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Return a specific error code - -ENOSPC - to signal the too small cert
data buffer instead of checking exit code and exitinfo2.
While at it, hoist the *fw_err assignment in snp_issue_guest_request()
so that a proper error value is returned to the callers.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
arch/x86/kernel/sev.c | 11 +++---
drivers/virt/coco/sev-guest/sev-guest.c | 46 ++++++++++++++-----------
2 files changed, 31 insertions(+), 26 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index c644c34372e8..6a3e1425ba17 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2209,15 +2209,16 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
if (ret)
goto e_put;
+ *fw_err = ghcb->save.sw_exit_info_2;
if (ghcb->save.sw_exit_info_2) {
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST &&
- ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN)
+ ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) {
input->data_npages = ghcb_get_rbx(ghcb);
-
- *fw_err = ghcb->save.sw_exit_info_2;
-
- ret = -EIO;
+ ret = -ENOSPC;
+ } else {
+ ret = -EIO;
+ }
}
e_put:
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index edaf6031c6d9..5b4cddf44a3a 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -322,7 +322,8 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
u8 type, void *req_buf, size_t req_sz, void *resp_buf,
u32 resp_sz, __u64 *fw_err)
{
- unsigned long err;
+ unsigned long err, override_err = 0;
+ unsigned int override_npages = 0;
u64 seqno;
int rc;
@@ -338,6 +339,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
if (rc)
return rc;
+retry_request:
/*
* Call firmware to process the request. In this function the encrypted
* message enters shared memory with the host. So after this call the
@@ -346,17 +348,24 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
*/
rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
- /*
- * If the extended guest request fails due to having too small of a
- * certificate data buffer, retry the same guest request without the
- * extended data request in order to increment the sequence number
- * and thus avoid IV reuse.
- */
- if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST &&
- err == SNP_GUEST_REQ_INVALID_LEN) {
- const unsigned int certs_npages = snp_dev->input.data_npages;
+ switch (rc) {
+ case -ENOSPC:
+ /*
+ * If the extended guest request fails due to having too
+ * small of a certificate data buffer, retry the same
+ * guest request without the extended data request in
+ * order to increment the sequence number and thus avoid
+ * IV reuse.
+ */
+ override_npages = snp_dev->input.data_npages;
+ exit_code = SVM_VMGEXIT_GUEST_REQUEST;
- exit_code = SVM_VMGEXIT_GUEST_REQUEST;
+ /*
+ * Override the error to inform callers the given extended
+ * request buffer size was too small and give the caller the
+ * required buffer size.
+ */
+ override_err = SNP_GUEST_REQ_INVALID_LEN;
/*
* If this call to the firmware succeeds, the sequence number can
@@ -366,19 +375,14 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
* of the VMPCK and the error code being propagated back to the
* user as an ioctl() return code.
*/
- rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
-
- /*
- * Override the error to inform callers the given extended
- * request buffer size was too small and give the caller the
- * required buffer size.
- */
- err = SNP_GUEST_REQ_INVALID_LEN;
- snp_dev->input.data_npages = certs_npages;
+ goto retry_request;
}
if (fw_err)
- *fw_err = err;
+ *fw_err = override_err ?: err;
+
+ if (override_npages)
+ snp_dev->input.data_npages = override_npages;
if (rc) {
dev_alert(snp_dev->dev,
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 04/11] virt/coco/sev-guest: Remove the disable_vmpck label in handle_guest_request()
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (2 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 03/11] virt/coco/sev-guest: Simplify extended guest request handling Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 05/11] virt/coco/sev-guest: Carve out the request issuing logic into a helper Borislav Petkov
` (6 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Call the function directly instead.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
drivers/virt/coco/sev-guest/sev-guest.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 5b4cddf44a3a..c0ecc5885573 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -388,7 +388,8 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
dev_alert(snp_dev->dev,
"Detected error from ASP request. rc: %d, fw_err: %llu\n",
rc, *fw_err);
- goto disable_vmpck;
+ snp_disable_vmpck(snp_dev);
+ return rc;
}
rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz);
@@ -396,17 +397,14 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
dev_alert(snp_dev->dev,
"Detected unexpected decode failure from ASP. rc: %d\n",
rc);
- goto disable_vmpck;
+ snp_disable_vmpck(snp_dev);
+ return rc;
}
/* Increment to new message sequence after payload decryption was successful. */
snp_inc_msg_seqno(snp_dev);
return 0;
-
-disable_vmpck:
- snp_disable_vmpck(snp_dev);
- return rc;
}
static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 05/11] virt/coco/sev-guest: Carve out the request issuing logic into a helper
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (3 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 04/11] virt/coco/sev-guest: Remove the disable_vmpck label in handle_guest_request() Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 06/11] virt/coco/sev-guest: Do some code style cleanups Borislav Petkov
` (5 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
This makes the code flow a lot easier to follow.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
drivers/virt/coco/sev-guest/sev-guest.c | 41 +++++++++++++++----------
1 file changed, 24 insertions(+), 17 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index c0ecc5885573..e72289de2b28 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -318,27 +318,12 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
return __enc_payload(snp_dev, req, payload, sz);
}
-static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver,
- u8 type, void *req_buf, size_t req_sz, void *resp_buf,
- u32 resp_sz, __u64 *fw_err)
+static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err)
{
unsigned long err, override_err = 0;
unsigned int override_npages = 0;
- u64 seqno;
int rc;
- /* Get message sequence and verify that its a non-zero */
- seqno = snp_get_msg_seqno(snp_dev);
- if (!seqno)
- return -EIO;
-
- memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
-
- /* Encrypt the userspace provided payload */
- rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
- if (rc)
- return rc;
-
retry_request:
/*
* Call firmware to process the request. In this function the encrypted
@@ -347,7 +332,6 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
* prevent reuse of the IV.
*/
rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
-
switch (rc) {
case -ENOSPC:
/*
@@ -384,6 +368,29 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
if (override_npages)
snp_dev->input.data_npages = override_npages;
+ return rc;
+}
+
+static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver,
+ u8 type, void *req_buf, size_t req_sz, void *resp_buf,
+ u32 resp_sz, __u64 *fw_err)
+{
+ u64 seqno;
+ int rc;
+
+ /* Get message sequence and verify that its a non-zero */
+ seqno = snp_get_msg_seqno(snp_dev);
+ if (!seqno)
+ return -EIO;
+
+ memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
+
+ /* Encrypt the userspace provided payload */
+ rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
+ if (rc)
+ return rc;
+
+ rc = __handle_guest_request(snp_dev, exit_code, fw_err);
if (rc) {
dev_alert(snp_dev->dev,
"Detected error from ASP request. rc: %d, fw_err: %llu\n",
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 06/11] virt/coco/sev-guest: Do some code style cleanups
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (4 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 05/11] virt/coco/sev-guest: Carve out the request issuing logic into a helper Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 07/11] virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case Borislav Petkov
` (4 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Remove unnecessary linebreaks, make the code more compact.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
drivers/virt/coco/sev-guest/sev-guest.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index e72289de2b28..d430e2be2a22 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -392,18 +392,14 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
rc = __handle_guest_request(snp_dev, exit_code, fw_err);
if (rc) {
- dev_alert(snp_dev->dev,
- "Detected error from ASP request. rc: %d, fw_err: %llu\n",
- rc, *fw_err);
+ dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err);
snp_disable_vmpck(snp_dev);
return rc;
}
rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz);
if (rc) {
- dev_alert(snp_dev->dev,
- "Detected unexpected decode failure from ASP. rc: %d\n",
- rc);
+ dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc);
snp_disable_vmpck(snp_dev);
return rc;
}
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 07/11] virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (5 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 06/11] virt/coco/sev-guest: Do some code style cleanups Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 08/11] crypto: ccp: Get rid of __sev_platform_init_locked()'s local function pointer Borislav Petkov
` (3 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
snp_issue_guest_request() checks the value returned by the hypervisor in
sw_exit_info_2 and returns a different error depending on it.
Convert those checks into a switch-case to make it more readable when
more error values are going to be checked in the future.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
arch/x86/kernel/sev.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 6a3e1425ba17..d67884fb38c1 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2210,15 +2210,21 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
goto e_put;
*fw_err = ghcb->save.sw_exit_info_2;
- if (ghcb->save.sw_exit_info_2) {
+ switch (*fw_err) {
+ case 0:
+ break;
+
+ case SNP_GUEST_REQ_INVALID_LEN:
/* Number of expected pages are returned in RBX */
- if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST &&
- ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) {
+ if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
input->data_npages = ghcb_get_rbx(ghcb);
ret = -ENOSPC;
- } else {
- ret = -EIO;
+ break;
}
+ fallthrough;
+ default:
+ ret = -EIO;
+ break;
}
e_put:
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 08/11] crypto: ccp: Get rid of __sev_platform_init_locked()'s local function pointer
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (6 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 07/11] virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 09/11] virt/coco/sev-guest: Add throttling awareness Borislav Petkov
` (2 subsequent siblings)
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: "Borislav Petkov (AMD)" <bp@alien8.de>
Add a wrapper instead.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
drivers/crypto/ccp/sev-dev.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f60bb73edfda..c54cc8f9a284 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -440,11 +440,18 @@ 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)
{
int rc = 0, psp_ret = SEV_RET_NO_FW_CALL;
struct psp_device *psp = psp_master;
- int (*init_function)(int *error);
struct sev_device *sev;
if (!psp || !psp->sev_data)
@@ -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
@@ -475,7 +479,7 @@ 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);
+ rc = __sev_do_init_locked(&psp_ret);
}
if (error)
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 09/11] virt/coco/sev-guest: Add throttling awareness
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (7 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 08/11] crypto: ccp: Get rid of __sev_platform_init_locked()'s local function pointer Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 10/11] virt/coco/sev-guest: Double-buffer messages Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument Borislav Petkov
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Borislav Petkov, Dionna Glaze, Joerg Roedel, Michael Roth,
Nikunj A Dadhania, Peter Gonda, Tom Lendacky, linux-coco, x86
From: Dionna Glaze <dionnaglaze@google.com>
A potentially malicious SEV guest can constantly hammer the hypervisor
using this driver to send down requests and thus prevent or at least
considerably hinder other guests from issuing requests to the secure
processor which is a shared platform resource.
Therefore, the host is permitted and encouraged to throttle such guest
requests.
Add the capability to handle the case when the hypervisor throttles
excessive numbers of requests issued by the guest. Otherwise, the VM
platform communication key will be disabled, preventing the guest from
attesting itself.
Realistically speaking, a well-behaved guest should not even care about
throttling. During its lifetime, it would end up issuing a handful of
requests which the hardware can easily handle.
This is more to address the case of a malicious guest. Such guest should
get throttled and if its VMPCK gets disabled, then that's its own
wrongdoing and perhaps that guest even deserves it.
To the implementation: the hypervisor signals with SNP_GUEST_REQ_ERR_BUSY
that the guest requests should be throttled. That error code is returned
in the upper 32-bit half of exitinfo2 and this is part of the GHCB spec
v2.
So the guest is given a throttling period of 1 minute in which it
retries the request every 2 seconds. This is a good default but if it
turns out to not pan out in practice, it can be tweaked later.
For safety, since the encryption algorithm in GHCBv2 is AES_GCM, control
must remain in the kernel to complete the request with the current
sequence number. Returning without finishing the request allows the
guest to make another request but with different message contents. This
is IV reuse, and breaks cryptographic protections.
[ bp: Rewrite commit message and do a simplified version. ]
Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs")
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230214164638.1189804-2-dionnaglaze@google.com
---
arch/x86/include/asm/sev-common.h | 3 ++-
arch/x86/kernel/sev.c | 4 ++++
drivers/virt/coco/sev-guest/sev-guest.c | 19 ++++++++++++++++++-
3 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index b8357d6ecd47..b63be696b776 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -128,8 +128,9 @@ struct snp_psc_desc {
struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY];
} __packed;
-/* Guest message request error code */
+/* Guest message request error codes */
#define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32)
+#define SNP_GUEST_REQ_ERR_BUSY BIT_ULL(33)
#define GHCB_MSR_TERM_REQ 0x100
#define GHCB_MSR_TERM_REASON_SET_POS 12
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index d67884fb38c1..3f664ab277c4 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2214,6 +2214,10 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
case 0:
break;
+ case SNP_GUEST_REQ_ERR_BUSY:
+ ret = -EAGAIN;
+ break;
+
case SNP_GUEST_REQ_INVALID_LEN:
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index d430e2be2a22..da4f6267baad 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -31,6 +31,9 @@
#define AAD_LEN 48
#define MSG_HDR_VER 1
+#define SNP_REQ_MAX_RETRY_DURATION (60*HZ)
+#define SNP_REQ_RETRY_DELAY (2*HZ)
+
struct snp_guest_crypto {
struct crypto_aead *tfm;
u8 *iv, *authtag;
@@ -320,7 +323,8 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err)
{
- unsigned long err, override_err = 0;
+ unsigned long err = 0xff, override_err = 0;
+ unsigned long req_start = jiffies;
unsigned int override_npages = 0;
int rc;
@@ -360,6 +364,19 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
* user as an ioctl() return code.
*/
goto retry_request;
+
+ /*
+ * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been
+ * throttled. Retry in the driver to avoid returning and reusing the
+ * message sequence number on a different message.
+ */
+ case -EAGAIN:
+ if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) {
+ rc = -ETIMEDOUT;
+ break;
+ }
+ schedule_timeout_killable(SNP_REQ_RETRY_DELAY);
+ goto retry_request;
}
if (fw_err)
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 10/11] virt/coco/sev-guest: Double-buffer messages
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (8 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 09/11] virt/coco/sev-guest: Add throttling awareness Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 11:34 ` [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument Borislav Petkov
10 siblings, 0 replies; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: Dionna Glaze <dionnaglaze@google.com>
The encryption algorithms read and write directly to shared unencrypted
memory, which may leak information as well as permit the host to tamper
with the message integrity. Instead, copy whole messages in or out as
needed before doing any computation on them.
Fixes: d5af44dde546 ("x86/sev: Provide support for SNP guest request NAEs")
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230214164638.1189804-3-dionnaglaze@google.com
---
drivers/virt/coco/sev-guest/sev-guest.c | 27 +++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index da4f6267baad..6bc1390b54e8 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -46,7 +46,15 @@ struct snp_guest_dev {
void *certs_data;
struct snp_guest_crypto *crypto;
+ /* request and response are in unencrypted memory */
struct snp_guest_msg *request, *response;
+
+ /*
+ * Avoid information leakage by double-buffering shared messages
+ * in fields that are in regular encrypted memory.
+ */
+ struct snp_guest_msg secret_request, secret_response;
+
struct snp_secrets_page_layout *layout;
struct snp_req_data input;
u32 *os_area_msg_seqno;
@@ -266,14 +274,17 @@ static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg,
static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz)
{
struct snp_guest_crypto *crypto = snp_dev->crypto;
- struct snp_guest_msg *resp = snp_dev->response;
- struct snp_guest_msg *req = snp_dev->request;
+ struct snp_guest_msg *resp = &snp_dev->secret_response;
+ struct snp_guest_msg *req = &snp_dev->secret_request;
struct snp_guest_msg_hdr *req_hdr = &req->hdr;
struct snp_guest_msg_hdr *resp_hdr = &resp->hdr;
dev_dbg(snp_dev->dev, "response [seqno %lld type %d version %d sz %d]\n",
resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, resp_hdr->msg_sz);
+ /* Copy response from shared memory to encrypted memory. */
+ memcpy(resp, snp_dev->response, sizeof(*resp));
+
/* Verify that the sequence counter is incremented by 1 */
if (unlikely(resp_hdr->msg_seqno != (req_hdr->msg_seqno + 1)))
return -EBADMSG;
@@ -297,7 +308,7 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type,
void *payload, size_t sz)
{
- struct snp_guest_msg *req = snp_dev->request;
+ struct snp_guest_msg *req = &snp_dev->secret_request;
struct snp_guest_msg_hdr *hdr = &req->hdr;
memset(req, 0, sizeof(*req));
@@ -400,13 +411,21 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
if (!seqno)
return -EIO;
+ /* Clear shared memory's response for the host to populate. */
memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
- /* Encrypt the userspace provided payload */
+ /* Encrypt the userspace provided payload in snp_dev->secret_request. */
rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
if (rc)
return rc;
+ /*
+ * Write the fully encrypted request to the shared unencrypted
+ * request page.
+ */
+ memcpy(snp_dev->request, &snp_dev->secret_request,
+ sizeof(snp_dev->secret_request));
+
rc = __handle_guest_request(snp_dev, exit_code, fw_err);
if (rc) {
dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err);
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument
2023-02-21 11:34 [PATCH -v2 00/11] SEV: Cleanup sev-guest a bit and add throttling Borislav Petkov
` (9 preceding siblings ...)
2023-02-21 11:34 ` [PATCH -v2 10/11] virt/coco/sev-guest: Double-buffer messages Borislav Petkov
@ 2023-02-21 11:34 ` Borislav Petkov
2023-02-21 15:43 ` Tom Lendacky
10 siblings, 1 reply; 14+ messages in thread
From: Borislav Petkov @ 2023-02-21 11:34 UTC (permalink / raw)
To: LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, Tom Lendacky, linux-coco, x86
From: Dionna Glaze <dionnaglaze@google.com>
The GHCB specification declares that the firmware error value for
a guest request will be stored in the lower 32 bits of EXIT_INFO_2. The
upper 32 bits are for the VMM's own error code. The fw_err argument to
snp_guest_issue_request() is thus a misnomer, and callers will need
access to all 64 bits.
The type of unsigned long also causes problems, since sw_exit_info2 is
u64 (unsigned long long) vs the argument's unsigned long*. Change this
type for issuing the guest request. Pass the ioctl command struct's error
field directly instead of in a local variable, since an incomplete guest
request may not set the error code, and uninitialized stack memory would
be written back to user space.
The firmware might not even be called, so bookend the call with the no
firmware call error and clear the error.
Since the "fw_err" field is really exitinfo2 split into the upper bits'
vmm error code and lower bits' firmware error code, convert the 64 bit
value to a union.
[ bp: Massage commit message, adjust code. ]
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230214164638.1189804-5-dionnaglaze@google.com
---
Documentation/virt/coco/sev-guest.rst | 20 ++++++----
arch/x86/include/asm/sev-common.h | 4 --
arch/x86/include/asm/sev.h | 8 ++--
arch/x86/kernel/sev.c | 15 ++++----
drivers/virt/coco/sev-guest/sev-guest.c | 49 +++++++++++++------------
include/uapi/linux/sev-guest.h | 18 ++++++++-
6 files changed, 68 insertions(+), 46 deletions(-)
diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst
index aa3e4c6a1f90..68b0d2363af8 100644
--- a/Documentation/virt/coco/sev-guest.rst
+++ b/Documentation/virt/coco/sev-guest.rst
@@ -37,11 +37,11 @@ along with a description:
the return value. General error numbers (-ENOMEM, -EINVAL)
are not detailed, but errors with specific meanings are.
-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, fw_err
-will be set to 0x00000000ffffffff, i.e., the lower 32-bits are -1.
+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
+the fw_error code will be set, otherwise fw_error will be set to -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
@@ -57,8 +57,14 @@ counter (e.g. counter overflow), then -EIO will be returned.
__u64 req_data;
__u64 resp_data;
- /* firmware error code on failure (see psp-sev.h) */
- __u64 fw_err;
+ /* bits[63:32]: VMM error code, bits[31:0] firmware error code (see psp-sev.h) */
+ union {
+ __u64 exitinfo2;
+ struct {
+ __u32 fw_error;
+ __u32 vmm_error;
+ };
+ };
};
2.1 SNP_GET_REPORT
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index b63be696b776..0759af9b1acf 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -128,10 +128,6 @@ struct snp_psc_desc {
struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY];
} __packed;
-/* Guest message request error codes */
-#define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32)
-#define SNP_GUEST_REQ_ERR_BUSY BIT_ULL(33)
-
#define GHCB_MSR_TERM_REQ 0x100
#define GHCB_MSR_TERM_REASON_SET_POS 12
#define GHCB_MSR_TERM_REASON_SET_MASK 0xf
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index ebc271bb6d8e..30567c72cbd9 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -185,6 +185,9 @@ static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
return rc;
}
+
+struct snp_guest_request_ioctl;
+
void setup_ghcb(void);
void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
unsigned int npages);
@@ -196,7 +199,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages);
void snp_set_wakeup_secondary_cpu(void);
bool snp_init(struct boot_params *bp);
void __init __noreturn snp_abort(void);
-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
+int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
@@ -216,8 +219,7 @@ static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npag
static inline void snp_set_wakeup_secondary_cpu(void) { }
static inline bool snp_init(struct boot_params *bp) { return false; }
static inline void snp_abort(void) { }
-static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input,
- unsigned long *fw_err)
+static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
{
return -ENOTTY;
}
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 3f664ab277c4..b031244d6d2d 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -22,6 +22,8 @@
#include <linux/efi.h>
#include <linux/platform_device.h>
#include <linux/io.h>
+#include <linux/psp-sev.h>
+#include <uapi/linux/sev-guest.h>
#include <asm/cpu_entry_area.h>
#include <asm/stacktrace.h>
@@ -2175,7 +2177,7 @@ static int __init init_sev_config(char *str)
}
__setup("sev=", init_sev_config);
-int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err)
+int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
{
struct ghcb_state state;
struct es_em_ctxt ctxt;
@@ -2183,8 +2185,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
struct ghcb *ghcb;
int ret;
- if (!fw_err)
- return -EINVAL;
+ rio->exitinfo2 = SEV_RET_NO_FW_CALL;
/*
* __sev_get_ghcb() needs to run with IRQs disabled because it is using
@@ -2209,16 +2210,16 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
if (ret)
goto e_put;
- *fw_err = ghcb->save.sw_exit_info_2;
- switch (*fw_err) {
+ rio->exitinfo2 = ghcb->save.sw_exit_info_2;
+ switch (rio->exitinfo2) {
case 0:
break;
- case SNP_GUEST_REQ_ERR_BUSY:
+ case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY):
ret = -EAGAIN;
break;
- case SNP_GUEST_REQ_INVALID_LEN:
+ case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
/* Number of expected pages are returned in RBX */
if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
input->data_npages = ghcb_get_rbx(ghcb);
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 6bc1390b54e8..6b3c1d308353 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -332,11 +332,12 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
return __enc_payload(snp_dev, req, payload, sz);
}
-static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err)
+static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
+ struct snp_guest_request_ioctl *rio)
{
- unsigned long err = 0xff, override_err = 0;
unsigned long req_start = jiffies;
unsigned int override_npages = 0;
+ u64 override_err = 0;
int rc;
retry_request:
@@ -346,7 +347,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
* sequence number must be incremented or the VMPCK must be deleted to
* prevent reuse of the IV.
*/
- rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
+ rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio);
switch (rc) {
case -ENOSPC:
/*
@@ -364,7 +365,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
* request buffer size was too small and give the caller the
* required buffer size.
*/
- override_err = SNP_GUEST_REQ_INVALID_LEN;
+ override_err = SNP_GUEST_VMM_ERR_INVALID_LEN << SNP_GUEST_VMM_ERR_SHIFT;
/*
* If this call to the firmware succeeds, the sequence number can
@@ -377,7 +378,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
goto retry_request;
/*
- * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been
+ * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been
* throttled. Retry in the driver to avoid returning and reusing the
* message sequence number on a different message.
*/
@@ -390,8 +391,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
goto retry_request;
}
- if (fw_err)
- *fw_err = override_err ?: err;
+ if (override_err)
+ rio->exitinfo2 = override_err;
if (override_npages)
snp_dev->input.data_npages = override_npages;
@@ -399,9 +400,10 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
return rc;
}
-static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver,
- u8 type, void *req_buf, size_t req_sz, void *resp_buf,
- u32 resp_sz, __u64 *fw_err)
+static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
+ struct snp_guest_request_ioctl *rio, u8 type,
+ void *req_buf, size_t req_sz, void *resp_buf,
+ u32 resp_sz)
{
u64 seqno;
int rc;
@@ -415,7 +417,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
/* Encrypt the userspace provided payload in snp_dev->secret_request. */
- rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
+ rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz);
if (rc)
return rc;
@@ -426,9 +428,11 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
memcpy(snp_dev->request, &snp_dev->secret_request,
sizeof(snp_dev->secret_request));
- rc = __handle_guest_request(snp_dev, exit_code, fw_err);
+ rc = __handle_guest_request(snp_dev, exit_code, rio);
if (rc) {
- dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err);
+ dev_alert(snp_dev->dev,
+ "Detected error from ASP request. rc: %d, exitinfo2: %llu\n",
+ rc, rio->exitinfo2);
snp_disable_vmpck(snp_dev);
return rc;
}
@@ -471,9 +475,9 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
if (!resp)
return -ENOMEM;
- rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version,
+ rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data,
- resp_len, &arg->fw_err);
+ resp_len);
if (rc)
goto e_free;
@@ -511,9 +515,8 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req)))
return -EFAULT;
- rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version,
- SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len,
- &arg->fw_err);
+ rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
+ SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len);
if (rc)
return rc;
@@ -573,12 +576,12 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
return -ENOMEM;
snp_dev->input.data_npages = npages;
- ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg->msg_version,
+ ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg,
SNP_MSG_REPORT_REQ, &req.data,
- sizeof(req.data), resp->data, resp_len, &arg->fw_err);
+ sizeof(req.data), resp->data, resp_len);
/* If certs length is invalid then copy the returned length */
- if (arg->fw_err == SNP_GUEST_REQ_INVALID_LEN) {
+ if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
req.certs_len = snp_dev->input.data_npages << PAGE_SHIFT;
if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req)))
@@ -613,7 +616,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
if (copy_from_user(&input, argp, sizeof(input)))
return -EFAULT;
- input.fw_err = 0xff;
+ input.exitinfo2 = 0xff;
/* Message version must be non-zero */
if (!input.msg_version)
@@ -644,7 +647,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
mutex_unlock(&snp_cmd_mutex);
- if (input.fw_err && copy_to_user(argp, &input, sizeof(input)))
+ if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input)))
return -EFAULT;
return ret;
diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h
index 256aaeff7e65..b25b728281ca 100644
--- a/include/uapi/linux/sev-guest.h
+++ b/include/uapi/linux/sev-guest.h
@@ -52,8 +52,14 @@ struct snp_guest_request_ioctl {
__u64 req_data;
__u64 resp_data;
- /* firmware error code on failure (see psp-sev.h) */
- __u64 fw_err;
+ /* bits[63:32]: VMM error code, bits[31:0] firmware error code (see psp-sev.h) */
+ union {
+ __u64 exitinfo2;
+ struct {
+ __u32 fw_error;
+ __u32 vmm_error;
+ };
+ };
};
struct snp_ext_report_req {
@@ -77,4 +83,12 @@ struct snp_ext_report_req {
/* Get SNP extended report as defined in the GHCB specification version 2. */
#define SNP_GET_EXT_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x2, struct snp_guest_request_ioctl)
+/* Guest message request EXIT_INFO_2 constants */
+#define SNP_GUEST_FW_ERR_MASK GENMASK_ULL(31, 0)
+#define SNP_GUEST_VMM_ERR_SHIFT 32
+#define SNP_GUEST_VMM_ERR(x) (((u64)x) << SNP_GUEST_VMM_ERR_SHIFT)
+
+#define SNP_GUEST_VMM_ERR_INVALID_LEN BIT(0)
+#define SNP_GUEST_VMM_ERR_BUSY BIT(1)
+
#endif /* __UAPI_LINUX_SEV_GUEST_H_ */
--
2.35.1
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument
2023-02-21 11:34 ` [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument Borislav Petkov
@ 2023-02-21 15:43 ` Tom Lendacky
2023-02-27 23:03 ` Dionna Amalie Glaze
0 siblings, 1 reply; 14+ messages in thread
From: Tom Lendacky @ 2023-02-21 15:43 UTC (permalink / raw)
To: Borislav Petkov, LKML
Cc: Dionna Glaze, Joerg Roedel, Michael Roth, Nikunj A Dadhania,
Peter Gonda, linux-coco, x86
On 2/21/23 05:34, Borislav Petkov wrote:
> From: Dionna Glaze <dionnaglaze@google.com>
>
> The GHCB specification declares that the firmware error value for
> a guest request will be stored in the lower 32 bits of EXIT_INFO_2. The
> upper 32 bits are for the VMM's own error code. The fw_err argument to
> snp_guest_issue_request() is thus a misnomer, and callers will need
> access to all 64 bits.
>
> The type of unsigned long also causes problems, since sw_exit_info2 is
> u64 (unsigned long long) vs the argument's unsigned long*. Change this
> type for issuing the guest request. Pass the ioctl command struct's error
> field directly instead of in a local variable, since an incomplete guest
> request may not set the error code, and uninitialized stack memory would
> be written back to user space.
>
> The firmware might not even be called, so bookend the call with the no
> firmware call error and clear the error.
>
> Since the "fw_err" field is really exitinfo2 split into the upper bits'
> vmm error code and lower bits' firmware error code, convert the 64 bit
> value to a union.
>
> [ bp: Massage commit message, adjust code. ]
>
> Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
> Link: https://lore.kernel.org/r/20230214164638.1189804-5-dionnaglaze@google.com
> ---
> Documentation/virt/coco/sev-guest.rst | 20 ++++++----
> arch/x86/include/asm/sev-common.h | 4 --
> arch/x86/include/asm/sev.h | 8 ++--
> arch/x86/kernel/sev.c | 15 ++++----
> drivers/virt/coco/sev-guest/sev-guest.c | 49 +++++++++++++------------
> include/uapi/linux/sev-guest.h | 18 ++++++++-
> 6 files changed, 68 insertions(+), 46 deletions(-)
>
> diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst
> index aa3e4c6a1f90..68b0d2363af8 100644
> --- a/Documentation/virt/coco/sev-guest.rst
> +++ b/Documentation/virt/coco/sev-guest.rst
> @@ -37,11 +37,11 @@ along with a description:
> the return value. General error numbers (-ENOMEM, -EINVAL)
> are not detailed, but errors with specific meanings are.
>
> -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, fw_err
> -will be set to 0x00000000ffffffff, i.e., the lower 32-bits are -1.
> +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
> +the fw_error code will be set, otherwise fw_error will be set to -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
> @@ -57,8 +57,14 @@ counter (e.g. counter overflow), then -EIO will be returned.
> __u64 req_data;
> __u64 resp_data;
>
> - /* firmware error code on failure (see psp-sev.h) */
> - __u64 fw_err;
> + /* bits[63:32]: VMM error code, bits[31:0] firmware error code (see psp-sev.h) */
> + union {
> + __u64 exitinfo2;
> + struct {
> + __u32 fw_error;
> + __u32 vmm_error;
> + };
> + };
> };
>
> 2.1 SNP_GET_REPORT
> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
> index b63be696b776..0759af9b1acf 100644
> --- a/arch/x86/include/asm/sev-common.h
> +++ b/arch/x86/include/asm/sev-common.h
> @@ -128,10 +128,6 @@ struct snp_psc_desc {
> struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY];
> } __packed;
>
> -/* Guest message request error codes */
> -#define SNP_GUEST_REQ_INVALID_LEN BIT_ULL(32)
> -#define SNP_GUEST_REQ_ERR_BUSY BIT_ULL(33)
> -
> #define GHCB_MSR_TERM_REQ 0x100
> #define GHCB_MSR_TERM_REASON_SET_POS 12
> #define GHCB_MSR_TERM_REASON_SET_MASK 0xf
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index ebc271bb6d8e..30567c72cbd9 100644
> --- a/arch/x86/include/asm/sev.h
> +++ b/arch/x86/include/asm/sev.h
> @@ -185,6 +185,9 @@ static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
>
> return rc;
> }
> +
> +struct snp_guest_request_ioctl;
> +
> void setup_ghcb(void);
> void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
> unsigned int npages);
> @@ -196,7 +199,7 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages);
> void snp_set_wakeup_secondary_cpu(void);
> bool snp_init(struct boot_params *bp);
> void __init __noreturn snp_abort(void);
> -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
> +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
> #else
> static inline void sev_es_ist_enter(struct pt_regs *regs) { }
> static inline void sev_es_ist_exit(void) { }
> @@ -216,8 +219,7 @@ static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npag
> static inline void snp_set_wakeup_secondary_cpu(void) { }
> static inline bool snp_init(struct boot_params *bp) { return false; }
> static inline void snp_abort(void) { }
> -static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input,
> - unsigned long *fw_err)
> +static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
> {
> return -ENOTTY;
> }
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 3f664ab277c4..b031244d6d2d 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -22,6 +22,8 @@
> #include <linux/efi.h>
> #include <linux/platform_device.h>
> #include <linux/io.h>
> +#include <linux/psp-sev.h>
> +#include <uapi/linux/sev-guest.h>
>
> #include <asm/cpu_entry_area.h>
> #include <asm/stacktrace.h>
> @@ -2175,7 +2177,7 @@ static int __init init_sev_config(char *str)
> }
> __setup("sev=", init_sev_config);
>
> -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err)
> +int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio)
> {
> struct ghcb_state state;
> struct es_em_ctxt ctxt;
> @@ -2183,8 +2185,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
> struct ghcb *ghcb;
> int ret;
>
> - if (!fw_err)
> - return -EINVAL;
> + rio->exitinfo2 = SEV_RET_NO_FW_CALL;
>
> /*
> * __sev_get_ghcb() needs to run with IRQs disabled because it is using
> @@ -2209,16 +2210,16 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
> if (ret)
> goto e_put;
>
> - *fw_err = ghcb->save.sw_exit_info_2;
> - switch (*fw_err) {
> + rio->exitinfo2 = ghcb->save.sw_exit_info_2;
> + switch (rio->exitinfo2) {
> case 0:
> break;
>
> - case SNP_GUEST_REQ_ERR_BUSY:
> + case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_BUSY):
> ret = -EAGAIN;
> break;
>
> - case SNP_GUEST_REQ_INVALID_LEN:
> + case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN):
> /* Number of expected pages are returned in RBX */
> if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
> input->data_npages = ghcb_get_rbx(ghcb);
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index 6bc1390b54e8..6b3c1d308353 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -332,11 +332,12 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
> return __enc_payload(snp_dev, req, payload, sz);
> }
>
> -static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, __u64 *fw_err)
> +static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> + struct snp_guest_request_ioctl *rio)
> {
> - unsigned long err = 0xff, override_err = 0;
> unsigned long req_start = jiffies;
> unsigned int override_npages = 0;
> + u64 override_err = 0;
> int rc;
>
> retry_request:
> @@ -346,7 +347,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> * sequence number must be incremented or the VMPCK must be deleted to
> * prevent reuse of the IV.
> */
> - rc = snp_issue_guest_request(exit_code, &snp_dev->input, &err);
> + rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio);
> switch (rc) {
> case -ENOSPC:
> /*
> @@ -364,7 +365,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> * request buffer size was too small and give the caller the
> * required buffer size.
> */
> - override_err = SNP_GUEST_REQ_INVALID_LEN;
> + override_err = SNP_GUEST_VMM_ERR_INVALID_LEN << SNP_GUEST_VMM_ERR_SHIFT;
Would it be better to do?:
override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN);
>
> /*
> * If this call to the firmware succeeds, the sequence number can
> @@ -377,7 +378,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> goto retry_request;
>
> /*
> - * The host may return SNP_GUEST_REQ_ERR_EBUSY if the request has been
> + * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been
> * throttled. Retry in the driver to avoid returning and reusing the
> * message sequence number on a different message.
> */
> @@ -390,8 +391,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> goto retry_request;
> }
>
> - if (fw_err)
> - *fw_err = override_err ?: err;
> + if (override_err)
> + rio->exitinfo2 = override_err;
>
> if (override_npages)
> snp_dev->input.data_npages = override_npages;
> @@ -399,9 +400,10 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> return rc;
> }
>
> -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, int msg_ver,
> - u8 type, void *req_buf, size_t req_sz, void *resp_buf,
> - u32 resp_sz, __u64 *fw_err)
> +static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> + struct snp_guest_request_ioctl *rio, u8 type,
> + void *req_buf, size_t req_sz, void *resp_buf,
> + u32 resp_sz)
> {
> u64 seqno;
> int rc;
> @@ -415,7 +417,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
> memset(snp_dev->response, 0, sizeof(struct snp_guest_msg));
>
> /* Encrypt the userspace provided payload in snp_dev->secret_request. */
> - rc = enc_payload(snp_dev, seqno, msg_ver, type, req_buf, req_sz);
> + rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz);
> if (rc)
> return rc;
>
> @@ -426,9 +428,11 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
> memcpy(snp_dev->request, &snp_dev->secret_request,
> sizeof(snp_dev->secret_request));
>
> - rc = __handle_guest_request(snp_dev, exit_code, fw_err);
> + rc = __handle_guest_request(snp_dev, exit_code, rio);
> if (rc) {
> - dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", rc, *fw_err);
> + dev_alert(snp_dev->dev,
> + "Detected error from ASP request. rc: %d, exitinfo2: %llu\n",
> + rc, rio->exitinfo2);
> snp_disable_vmpck(snp_dev);
> return rc;
> }
> @@ -471,9 +475,9 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
> if (!resp)
> return -ENOMEM;
>
> - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version,
> + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
> SNP_MSG_REPORT_REQ, &req, sizeof(req), resp->data,
> - resp_len, &arg->fw_err);
> + resp_len);
> if (rc)
> goto e_free;
>
> @@ -511,9 +515,8 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
> if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req)))
> return -EFAULT;
>
> - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version,
> - SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len,
> - &arg->fw_err);
> + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg,
> + SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len);
> if (rc)
> return rc;
>
> @@ -573,12 +576,12 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
> return -ENOMEM;
>
> snp_dev->input.data_npages = npages;
> - ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg->msg_version,
> + ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg,
> SNP_MSG_REPORT_REQ, &req.data,
> - sizeof(req.data), resp->data, resp_len, &arg->fw_err);
> + sizeof(req.data), resp->data, resp_len);
>
> /* If certs length is invalid then copy the returned length */
> - if (arg->fw_err == SNP_GUEST_REQ_INVALID_LEN) {
> + if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
> req.certs_len = snp_dev->input.data_npages << PAGE_SHIFT;
>
> if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req)))
> @@ -613,7 +616,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
> if (copy_from_user(&input, argp, sizeof(input)))
> return -EFAULT;
>
> - input.fw_err = 0xff;
> + input.exitinfo2 = 0xff;
Should this be?
input.exitinfo2 = SEV_RET_NO_FW_CALL;
or make it part of patch #1?
>
> /* Message version must be non-zero */
> if (!input.msg_version)
> @@ -644,7 +647,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
>
> mutex_unlock(&snp_cmd_mutex);
>
> - if (input.fw_err && copy_to_user(argp, &input, sizeof(input)))
> + if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input)))
> return -EFAULT;
>
> return ret;
> diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h
> index 256aaeff7e65..b25b728281ca 100644
> --- a/include/uapi/linux/sev-guest.h
> +++ b/include/uapi/linux/sev-guest.h
> @@ -52,8 +52,14 @@ struct snp_guest_request_ioctl {
> __u64 req_data;
> __u64 resp_data;
>
> - /* firmware error code on failure (see psp-sev.h) */
> - __u64 fw_err;
> + /* bits[63:32]: VMM error code, bits[31:0] firmware error code (see psp-sev.h) */
> + union {
> + __u64 exitinfo2;
> + struct {
> + __u32 fw_error;
> + __u32 vmm_error;
> + };
> + };
> };
>
> struct snp_ext_report_req {
> @@ -77,4 +83,12 @@ struct snp_ext_report_req {
> /* Get SNP extended report as defined in the GHCB specification version 2. */
> #define SNP_GET_EXT_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x2, struct snp_guest_request_ioctl)
>
> +/* Guest message request EXIT_INFO_2 constants */
> +#define SNP_GUEST_FW_ERR_MASK GENMASK_ULL(31, 0)
> +#define SNP_GUEST_VMM_ERR_SHIFT 32
> +#define SNP_GUEST_VMM_ERR(x) (((u64)x) << SNP_GUEST_VMM_ERR_SHIFT)
> +
> +#define SNP_GUEST_VMM_ERR_INVALID_LEN BIT(0)
> +#define SNP_GUEST_VMM_ERR_BUSY BIT(1)
These are actually supposed to be numbers, not bits. It works out that
INVALID_LEN is 1 and BUSY is 2, but the next value (in the GHCB spec) will
be 3, so lets change these to 1 and 2.
This could be fixed in patch #9 or here as/at the final change.
Thanks,
Tom
> +
> #endif /* __UAPI_LINUX_SEV_GUEST_H_ */
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH -v2 11/11] x86/sev: Change snp_guest_issue_request()'s fw_err argument
2023-02-21 15:43 ` Tom Lendacky
@ 2023-02-27 23:03 ` Dionna Amalie Glaze
0 siblings, 0 replies; 14+ messages in thread
From: Dionna Amalie Glaze @ 2023-02-27 23:03 UTC (permalink / raw)
To: Tom Lendacky
Cc: Borislav Petkov, LKML, Joerg Roedel, Michael Roth,
Nikunj A Dadhania, Peter Gonda, linux-coco, x86
>
> Should this be?
>
> input.exitinfo2 = SEV_RET_NO_FW_CALL;
>
> or make it part of patch #1?
>
This is something I'm not fully 100% on. You said that there's not
that many bits for firmware errors, so -1 or 0xff are fine by me so
long as neither are possible results from the firmware. I don't recall
the details on that, so if we go back to 0xff for SEV_RET_NO_FW_CALL,
I'd want a clearer explanation for why 0xff is sufficient.
Apart from the other comments from Tom which are a matter of style and
not semantics,
Tested-by: Dionna Glaze <dionnaglaze@google.com>
--
-Dionna Glaze, PhD (she/her)
^ permalink raw reply [flat|nested] 14+ messages in thread