From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-sgx@vger.kernel.org
Subject: [PATCH for_v23 v2 2/9] x86/sgx: Do not EWB SECS if the enclave is dead
Date: Thu, 10 Oct 2019 16:21:01 -0700 [thread overview]
Message-ID: <20191010232108.27075-3-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191010232108.27075-1-sean.j.christopherson@intel.com>
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(-)
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);
}
--
2.22.0
next prev parent reply other threads:[~2019-10-10 23:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 23:20 [PATCH for_v23 v2 0/9] x86/sgx: Misc page related fixes Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 1/9] x86/sgx: WARN once if an enclave is released with unfreed EPC pages Sean Christopherson
2019-10-10 23:21 ` Sean Christopherson [this message]
2019-10-10 23:21 ` [PATCH for_v23 v2 3/9] x86/sgx: Fix a memory leak in sgx_encl_destroy() Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 4/9] x86/sgx: WARN on any non-zero return from __eremove() Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 5/9] x86/sgx: WARN only once if EREMOVE fails Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 6/9] x86/sgx: Split second half of sgx_free_page() to a separate helper Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 7/9] x86/sgx: Use the post-reclaim variant of __sgx_free_page() Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 8/9] x86/sgx: Don't update free page count if EPC section allocation fails Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 9/9] x86/sgx: Reinstate per EPC section free page counts Sean Christopherson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191010232108.27075-3-sean.j.christopherson@intel.com \
--to=sean.j.christopherson@intel.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=linux-sgx@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).