crypto: ccp - Do not initialize SNP for ioctl(SNP_COMMIT)

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 SNP_COMMIT command does not require the firmware to be in any
particular state. Skip initializing it if it was previously uninitialized.

The SEV-SNP firmware specification doc 56860 does not mention SNP_COMMIT in
Table 5 as a command that is allowed in the UNINIT state, but it is in fact
allowed and a future documentation update will reflect that.

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
CC: <stable@vger.kernel.org>
Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 46c5d7ee7955ac25cd0a92f733ab8fedcd66062d..de472f0503cbefe3550e3285e3735be775c48152 100644 (file)
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -2440,24 +2440,13 @@ cleanup:
 
 static int sev_ioctl_do_snp_commit(struct sev_issue_cmd *argp)
 {
-       struct sev_device *sev = psp_master->sev_data;
        struct sev_data_snp_commit buf;
-       bool shutdown_required = false;
-       int ret, error;
-
-       if (!sev->snp_initialized) {
-               ret = snp_move_to_init_state(argp, &shutdown_required);
-               if (ret)
-                       return ret;
-       }
+       int ret;
 
        buf.len = sizeof(buf);
 
        ret = __sev_do_cmd_locked(SEV_CMD_SNP_COMMIT, &buf, &argp->error);
 
-       if (shutdown_required)
-               __sev_snp_shutdown_locked(&error, false);
-
        return ret;
 }