SGX EPC pages go through the following life cycle:
DIRTY ---> FREE ---> IN-USE --\
^ |
\-----------------/
Recovery action for poison for a DIRTY or FREE page is simple. Just
make sure never to allocate the page. IN-USE pages need some extra
handling.
Add a new flag bit SGX_EPC_PAGE_IS_FREE that is set when a page
is added to a free list and cleared when the page is allocated.
Notes:
1) These transitions are made while holding the node->lock so that
future code that checks the flags while holding the node->lock
can be sure that if the SGX_EPC_PAGE_IS_FREE bit is set, then the
page is on the free list.
2) Initially while the pages are on the dirty list the
SGX_EPC_PAGE_IS_FREE bit is cleared.
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Tested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
arch/x86/kernel/cpu/sgx/main.c | 2 ++
arch/x86/kernel/cpu/sgx/sgx.h | 3 +++
2 files changed, 5 insertions(+)
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de02bbcc..825aa91516c8 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -472,6 +472,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
list_del_init(&page->list);
sgx_nr_free_pages--;
+ page->flags = 0;
spin_unlock(&node->lock);
@@ -626,6 +627,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
list_add_tail(&page->list, &node->free_page_list);
sgx_nr_free_pages++;
+ page->flags = SGX_EPC_PAGE_IS_FREE;
spin_unlock(&node->lock);
}
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 4628acec0009..5906471156c5 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -26,6 +26,9 @@
/* Pages, which are being tracked by the page reclaimer. */
#define SGX_EPC_PAGE_RECLAIMER_TRACKED BIT(0)
+/* Pages on free list */
+#define SGX_EPC_PAGE_IS_FREE BIT(1)
+
struct sgx_epc_page {
unsigned int section;
unsigned int flags;
--
2.31.1
