[RFC PATCH v3 04/27] x86/sgx: Wipe out EREMOVE from sgx_free_epc_page()

Kai Huang
2021-01-26T16:13:51Z

From: Jarkko Sakkinen <jarkko@kernel.org>

Encapsulate the snippet in sgx_free_epc_page() concerning EREMOVE to
sgx_reset_epc_page(), which is a static helper function for
sgx_encl_release(). It's the only function existing, which deals with
initialized pages.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
arch/x86/kernel/cpu/sgx/encl.c | 13 +++++++++++++
arch/x86/kernel/cpu/sgx/main.c | 10 ++++------
2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index ee50a5010277..a78b71447771 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -389,6 +389,16 @@ const struct vm_operations_struct sgx_vm_ops = {
.access = sgx_vma_access,
};

+
+static void sgx_reset_epc_page(struct sgx_epc_page *epc_page)
+{
+ int ret;
+
+ ret = __eremove(sgx_get_epc_virt_addr(epc_page));
+ if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret))
+ return;
+}
+
/**
* sgx_encl_release - Destroy an enclave instance
* @kref: address of a kref inside &sgx_encl
@@ -412,6 +422,7 @@ void sgx_encl_release(struct kref *ref)
if (sgx_unmark_page_reclaimable(entry->epc_page))
continue;

+ sgx_reset_epc_page(entry->epc_page);
sgx_free_epc_page(entry->epc_page);
encl->secs_child_cnt--;
entry->epc_page = NULL;
@@ -423,6 +434,7 @@ void sgx_encl_release(struct kref *ref)
xa_destroy(&encl->page_array);

if (!encl->secs_child_cnt && encl->secs.epc_page) {
+ sgx_reset_epc_page(encl->secs.epc_page);
sgx_free_epc_page(encl->secs.epc_page);
encl->secs.epc_page = NULL;
}
@@ -431,6 +443,7 @@ void sgx_encl_release(struct kref *ref)
va_page = list_first_entry(&encl->va_pages, struct sgx_va_page,
list);
list_del(&va_page->list);
+ sgx_reset_epc_page(va_page->epc_page);
sgx_free_epc_page(va_page->epc_page);
kfree(va_page);
}
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index f330abdb5bb1..21c2ffa13870 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -598,16 +598,14 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
* sgx_free_epc_page() - Free an EPC page
* @page: an EPC page
*
- * Call EREMOVE for an EPC page and insert it back to the list of free pages.
+ * Put the EPC page back to the list of free pages. It's the callers
+ * responsibility to make sure that the page is in uninitialized state In other
+ * words, do EREMOVE, EWB or whatever operation is necessary before calling
+ * this function.
*/
void sgx_free_epc_page(struct sgx_epc_page *page)
{
struct sgx_epc_section *section = &sgx_epc_sections[page->section];
- int ret;
-
- ret = __eremove(sgx_get_epc_virt_addr(page));
- if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret))
- return;

spin_lock(&section->lock);
list_add_tail(&page->list, &section->page_list);
--
2.29.2