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

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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: ceac7fb89e ("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>
This commit is contained in:
Tycho Andersen (AMD) 2026-05-04 10:51:45 -06:00 committed by Herbert Xu
parent fb1758e74b
commit 5a1364da2f
1 changed files with 1 additions and 12 deletions
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13
drivers/crypto/ccp/sev-dev.c
View File

@ -2440,24 +2440,13 @@ static int sev_ioctl_do_snp_platform_status(struct sev_issue_cmd *argp)
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;
}