Re: [PATCH v5 16/18] x86/sgx: Limit process EPC usage with misc cgroup controller

Huang, Kai
2023-10-10T00:17:03Z

> +static inline struct sgx_epc_lru_lists *epc_cg_lru(struct sgx_epc_cgroup *epc_cg)
> +{
> + if (epc_cg)
> + return &epc_cg->lru;
> + return NULL;
> +}
>

It's legal to return NULL EPC cgroup for a given EPC page, i.e., when the
enclave isn't assigned to any cgroup. But ...

>
> static inline struct sgx_epc_lru_lists *sgx_lru_lists(struct sgx_epc_page *epc_page)
> {
> + if (IS_ENABLED(CONFIG_CGROUP_SGX_EPC))
> + return epc_cg_lru(epc_page->epc_cg);
> +
> return &sgx_global_lru;
> }

... here is it legal to return a NULL LRU list?

It appears you always want to return a valid LRU list. That is, if EPC cgroup
is enabled, and when the EPC page doesn't belong to any cgroup, then you want to
return the sgx_global_lru ?