Re: [PATCH v5 07/18] x86/sgx: Introduce RECLAIM_IN_PROGRESS state

Huang, Kai
2023-09-27T10:42:27Z

> @@ -312,13 +312,15 @@ static void sgx_reclaim_pages(void)
> list_del_init(&epc_page->list);
> encl_page = epc_page->owner;
>
> - if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
> + if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
> + sgx_epc_page_set_state(epc_page, SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
> chunk[cnt++] = epc_page;
> - else
> + } else {
> /* The owner is freeing the page. No need to add the
> * page back to the list of reclaimable pages.
> */

Please use proper comment style:

For single line comment:

/* ... */

For multiple lines comment:

/*
* ...
*/

> sgx_epc_page_reset_state(epc_page);
> + }

Nit: unintended new {} around 'else'?

> }
> spin_unlock(&sgx_global_lru.lock);
>
> @@ -528,16 +530,13 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
> int sgx_drop_epc_page(struct sgx_epc_page *page)
> {
> spin_lock(&sgx_global_lru.lock);
> - if (sgx_epc_page_reclaimable(page->flags)) {
> - /* The page is being reclaimed. */
> - if (list_empty(&page->list)) {
> - spin_unlock(&sgx_global_lru.lock);
> - return -EBUSY;
> - }
> -
> - list_del(&page->list);
> - sgx_epc_page_reset_state(page);
> + if (sgx_epc_page_reclaim_in_progress(page->flags)) {
> + spin_unlock(&sgx_global_lru.lock);
> + return -EBUSY;
> }
> +
> + list_del(&page->list);
> + sgx_epc_page_reset_state(page);
> spin_unlock(&sgx_global_lru.lock);
>
> return 0;
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index 2faeb40b345f..764cec23f4e5 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -40,6 +40,8 @@ enum sgx_epc_page_state {
>
> /* Page is in use and tracked in a reclaimable LRU list
> * Becomes NOT_TRACKED after sgx_drop_epc()
> + * Becomes RECLAIM_IN_PROGRESS in sgx_reclaim_pages() when identified
> + * for reclaiming
> */
> SGX_EPC_PAGE_RECLAIMABLE = 2,
>
> @@ -50,6 +52,14 @@ enum sgx_epc_page_state {
> */
> SGX_EPC_PAGE_UNRECLAIMABLE = 3,
>
> + /* Page is being prepared for reclamation, tracked in a temporary
> + * isolated list by the reclaimer.
> + * Changes in sgx_reclaim_pages() back to RECLAIMABLE if preparation
> + * fails for any reason.
> + * Becomes NOT_TRACKED if reclaimed successfully in sgx_reclaim_pages()
> + * and immediately sgx_free_epc() is called to make it FREE.
> + */

Ditto for the comment style.

And please use blank line to separate paragraphs for better readability.