On 7/17/23 13:29, Haitao Huang wrote: ...
@@ -248,11 +258,9 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl, return entry; }
- if (!(encl->secs.epc_page)) {
epc_page = sgx_encl_eldu(&encl->secs, NULL);if (IS_ERR(epc_page))return ERR_CAST(epc_page);- }
- epc_page = sgx_encl_load_secs(encl);
- if (IS_ERR(epc_page))
return ERR_CAST(epc_page);epc_page = sgx_encl_eldu(entry, encl->secs.epc_page); if (IS_ERR(epc_page)) @@ -339,6 +347,13 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, mutex_lock(&encl->lock);
- epc_page = sgx_encl_load_secs(encl);
- if (IS_ERR(epc_page)) {
if (PTR_ERR(epc_page) == -EBUSY)vmret = VM_FAULT_NOPAGE;goto err_out_unlock;- }
Whenever I see one of these "make sure it isn't NULL", I always jump to asking what *keeps* it from becoming NULL again. In both cases here, I think that's encl->lock.
A comment would be really nice here, maybe on sgx_encl_load_secs(). Maybe:
/* * Ensure the SECS page is not swapped out. Must be called with * encl->lock to protect _____ and ensure the SECS page is not * swapped out again. */
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 166692f2d501..4662a364ce62 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -257,6 +257,10 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page, mutex_lock(&encl->lock);
- /* Should not be possible */
- if (WARN_ON(!(encl->secs.epc_page)))
goto out;
That comment isn't super helpful. We generally don't WARN_ON() things that should happen. *Why* is it not possible?