Tycho Andersen (AMD) 7a361c74bb crypto: ccp - Do not initialize SNP for ioctl(SNP_COMMIT)
commit 5a1364da2f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-07-18 16:53:28 +02:00
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