[PATCH v1 3/4] crypto/ccp: Do not initialize SNP for ioctl(SNP_VLEK_LOAD)

[Tycho Andersen]

From: "Tycho Andersen (AMD)" <tycho@xxxxxxxxxx>

Sashiko notes:

> if SEV initialization fails and KVM is actively running normal VMs, could a
> userspace process trigger this code path via /dev/sev ioctls (e.g.,
> SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN
> execution for an active VM trigger a general protection fault and crash the
> host?

The SEV firmware docs for SNP_VLEK_LOAD note:

> On SNP_SHUTDOWN, the VLEK is deleted.

That is, the initialization/shutdown wrapper here is pointless, because the
firmware immediately throws away the key anyway. Instead, refuse to do
anything if SNP has not been previously initialized.

Fixes: ceac7fb89e8d ("crypto: ccp - Ensure implicit SEV/SNP init and shutdown in ioctls")
Reported-by: Sashiko
Assisted-by: Gemini:gemini-3.1-pro-preview
Link: https://sashiko.dev/#/patchset/20260324161301.1353976-1-tycho%40kernel.org
Signed-off-by: Tycho Andersen (AMD) <tycho@xxxxxxxxxx>
---
 drivers/crypto/ccp/sev-dev.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 572f06368d4b..e8c3ac6d989a 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -2481,9 +2481,8 @@ static int sev_ioctl_do_snp_vlek_load(struct sev_issue_cmd *argp, bool writable)
 {
 	struct sev_device *sev = psp_master->sev_data;
 	struct sev_user_data_snp_vlek_load input;
-	bool shutdown_required = false;
-	int ret, error;
 	void *blob;
+	int ret;
 
 	if (!argp->data)
 		return -EINVAL;
@@ -2497,6 +2496,9 @@ static int sev_ioctl_do_snp_vlek_load(struct sev_issue_cmd *argp, bool writable)
 	if (input.len != sizeof(input) || input.vlek_wrapped_version != 0)
 		return -EINVAL;
 
+	if (!sev->snp_initialized)
+		return -EINVAL;
+
 	blob = psp_copy_user_blob(input.vlek_wrapped_address,
 				  sizeof(struct sev_user_data_snp_wrapped_vlek_hashstick));
 	if (IS_ERR(blob))
@@ -2504,18 +2506,7 @@ static int sev_ioctl_do_snp_vlek_load(struct sev_issue_cmd *argp, bool writable)
 
 	input.vlek_wrapped_address = __psp_pa(blob);
 
-	if (!sev->snp_initialized) {
-		ret = snp_move_to_init_state(argp, &shutdown_required);
-		if (ret)
-			goto cleanup;
-	}
-
 	ret = __sev_do_cmd_locked(SEV_CMD_SNP_VLEK_LOAD, &input, &argp->error);
-
-	if (shutdown_required)
-		__sev_snp_shutdown_locked(&error, false);
-
-cleanup:
 	kfree(blob);
 
 	return ret;
-- 
2.53.0