diff mbox series

[for_v23,2/9] x86/sgx: Do not EWB SECS if the enclave is dead

Message ID 20191010214301.25669-3-sean.j.christopherson@intel.com (mailing list archive)
State New, archived
Headers show
Series x86/sgx: misc page related fixes | expand

Commit Message

Sean Christopherson Oct. 10, 2019, 9:42 p.m. UTC 
Don't EWB if the enclave is dead when opportunistically zapping the SECS
during reclaim as VA pages are freed by sgx_encl_destroy(), i.e.
sgx_encl_ewb() will consume a bad encl->va_pages if the enclave has been
destroyed.

Add a comment in sgx_encl_destroy() to explicit call out that it's ok to
free VA pages.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/cpu/sgx/encl.c    |  6 +++++-
 arch/x86/kernel/cpu/sgx/reclaim.c | 19 +++++++++++--------
 2 files changed, 16 insertions(+), 9 deletions(-)

Comments

Jarkko Sakkinen Oct. 14, 2019, 8:58 p.m. UTC | #1 
On Thu, Oct 10, 2019 at 02:42:54PM -0700, Sean Christopherson wrote:
> Don't EWB if the enclave is dead when opportunistically zapping the SECS
> during reclaim as VA pages are freed by sgx_encl_destroy(), i.e.
> sgx_encl_ewb() will consume a bad encl->va_pages if the enclave has been
> destroyed.
> 
> Add a comment in sgx_encl_destroy() to explicit call out that it's ok to
> free VA pages.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>

Thank you.

Merged.

/Jarkko
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index b4d7b2f9609f..ea21d3737a32 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -484,7 +484,11 @@  void sgx_encl_destroy(struct sgx_encl *encl)
 		encl->secs.epc_page = NULL;
 	}
 
-
+	/*
+	 * The reclaimer is responsible for checking SGX_ENCL_DEAD before doing
+	 * EWB, thus it's safe to free VA pages even if the reclaimer holds a
+	 * reference to the enclave.
+	 */
 	while (!list_empty(&encl->va_pages)) {
 		va_page = list_first_entry(&encl->va_pages, struct sgx_va_page,
 					   list);
diff --git a/arch/x86/kernel/cpu/sgx/reclaim.c b/arch/x86/kernel/cpu/sgx/reclaim.c
index 391fbc3e7e98..8143c9a20894 100644
--- a/arch/x86/kernel/cpu/sgx/reclaim.c
+++ b/arch/x86/kernel/cpu/sgx/reclaim.c
@@ -321,16 +321,19 @@  static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
 	encl_page->epc_page = NULL;
 	encl->secs_child_cnt--;
 
-	if (!encl->secs_child_cnt &&
-	    (atomic_read(&encl->flags) &
-	     (SGX_ENCL_DEAD | SGX_ENCL_INITIALIZED))) {
-		ret = sgx_encl_get_backing(encl, PFN_DOWN(encl->size),
-					   &secs_backing);
-		if (!ret) {
-			sgx_encl_ewb(encl->secs.epc_page, &secs_backing);
+	if (!encl->secs_child_cnt) {
+		if (atomic_read(&encl->flags) & SGX_ENCL_DEAD) {
 			sgx_free_page(encl->secs.epc_page);
-
 			encl->secs.epc_page = NULL;
+		} else if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
+			ret = sgx_encl_get_backing(encl, PFN_DOWN(encl->size),
+						   &secs_backing);
+			if (!ret) {
+				sgx_encl_ewb(encl->secs.epc_page, &secs_backing);
+
+				sgx_free_page(encl->secs.epc_page);
+				encl->secs.epc_page = NULL;
+			}
 
 			sgx_encl_put_backing(&secs_backing, true);
 		}