Re: [PATCH v3] x86/sgx: Do not consider unsanitized pages an error

Dave Hansen
2022-08-25T18:38:05Z

On 8/25/22 11:27, Jarkko Sakkinen wrote:
> On Thu, Aug 25, 2022 at 07:07:44AM -0700, Dave Hansen wrote:
>> On 8/25/22 01:08, Jarkko Sakkinen wrote:
>>> However, if the SGX subsystem initialization is retracted, the sanitization
>>> process could end up in the middle, and sgx_dirty_page_list be left
>>> non-empty for legit reasons.
>> What does "retraction" mean in this context?
> Rest of the initialization failing or features not detected (-ENODEV).

Can you please work on communicating better descriptions of the
problems? This really isn't good enough.

I think you're talking about sgx_init(). It launches ksgxd from
sgx_page_reclaimer_init() which sets about sanitizing the
'dirty_page_list'. After launching ksgxd, if later actions in
sgx_init() (misc_register(), sgx_drv_init(), sgx_vepc_init()) fail,
ksgxd will be stopped prematurely.

This will leave pages in 'sgx_dirty_page_list' after
__sgx_sanitize_pages() has completed, which results in a WARN_ON().

The WARN_ON() is really only valid when __sgx_sanitize_pages() runs to
completion *and* fails to empty 'sgx_dirty_page_list'.

Is that it?

If so, could you please give the changelog another go?