Re: [PATCH 1/2] crypto: ccp - Fix a case where SNP_SHUTDOWN is missed

[Guenter Roeck]

Hi,

On Mon, Jan 05, 2026 at 10:22:17AM -0700, Tycho Andersen wrote:
> From: Tom Lendacky <thomas.lendacky@xxxxxxx>
> 
> If page reclaim fails in sev_ioctl_do_snp_platform_status() and SNP was
> moved from UNINIT to INIT for the function, SNP is not moved back to
> UNINIT state. Additionally, SNP is not required to be initialized in order
> to execute the SNP_PLATFORM_STATUS command, so don't attempt to move to
> INIT state and let SNP_PLATFORM_STATUS report the status as is.
> 
> Fixes: ceac7fb89e8d ("crypto: ccp - Ensure implicit SEV/SNP init and shutdown in ioctls")
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Reviewed-by: Tycho Andersen (AMD) <tycho@xxxxxxxxxx>
> Reviewed-by: Alexey Kardashevskiy <aik@xxxxxxx>
> Signed-off-by: Tycho Andersen (AMD) <tycho@xxxxxxxxxx>
> ---
>  drivers/crypto/ccp/sev-dev.c | 46 ++++++++++++++++++------------------
>  1 file changed, 23 insertions(+), 23 deletions(-)
> 
> -	if (snp_reclaim_pages(__pa(data), 1, true))
> -		return -EFAULT;
> +	if (sev->snp_initialized) {
> +		/*
> +		 * The status page will be in Reclaim state on success, or left
> +		 * in Firmware state on failure. Use snp_reclaim_pages() to
> +		 * transition either case back to Hypervisor-owned state.
> +		 */
> +		if (snp_reclaim_pages(__pa(data), 1, true)) {
> +			snp_leak_pages(__page_to_pfn(status_page), 1);

This change got flagged by an experimental AI agent:

  If `snp_reclaim_pages()` fails, it already internally calls
  `snp_leak_pages()`. Does calling `snp_leak_pages()` a second time
  on the exact same page corrupt the `snp_leaked_pages_list` because
  `list_add_tail(&page->buddy_list, &snp_leaked_pages_list)` is
  executed again?

I don't claim to understand the code, but it does look like snp_leak_pages()
is indeed called twice on the same page, which does suggest that it is added
twice to the leaked pages list if it is not a compound page.

Does this make sense, or is the AI missing something ?

Thanks,
Guenter