[RFC PATCH 08/20] x86/sgx: Add EPC page flags to identify type of page

Kristen Carlson Accardi
2022-09-22T17:10:45Z

From: Sean Christopherson <sean.j.christopherson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Create new flags to help identify whether a page is an enclave page
or a va page and save the page type when the page is recorded.

Signed-off-by: Sean Christopherson <sean.j.christopherson-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Kristen Carlson Accardi <kristen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: Sean Christopherson <seanjc-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
---
arch/x86/kernel/cpu/sgx/encl.c | 6 +++---
arch/x86/kernel/cpu/sgx/ioctl.c | 4 ++--
arch/x86/kernel/cpu/sgx/main.c | 20 ++++++++++----------
arch/x86/kernel/cpu/sgx/sgx.h | 8 +++++++-
4 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index ad611c06798f..672b302f3688 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -252,7 +252,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
epc_page = sgx_encl_eldu(&encl->secs, NULL);
if (IS_ERR(epc_page))
return ERR_CAST(epc_page);
- sgx_record_epc_page(epc_page, 0);
+ sgx_record_epc_page(epc_page, SGX_EPC_PAGE_ENCLAVE);
}

epc_page = sgx_encl_eldu(entry, encl->secs.epc_page);
@@ -260,7 +260,7 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl,
return ERR_CAST(epc_page);

encl->secs_child_cnt++;
- sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
+ sgx_record_epc_page(entry->epc_page, SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE);

return entry;
}
@@ -1221,7 +1221,7 @@ struct sgx_epc_page *sgx_alloc_va_page(struct sgx_encl *encl, bool reclaim)
sgx_encl_free_epc_page(epc_page);
return ERR_PTR(-EFAULT);
}
- sgx_record_epc_page(epc_page, 0);
+ sgx_record_epc_page(epc_page, SGX_EPC_PAGE_VERSION_ARRAY);

epc_page->owner = encl;

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index aca80a3f38a1..c91cc6a01232 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -114,7 +114,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
encl->attributes = secs->attributes;
encl->attributes_mask = SGX_ATTR_DEBUG | SGX_ATTR_MODE64BIT | SGX_ATTR_KSS;

- sgx_record_epc_page(encl->secs.epc_page, 0);
+ sgx_record_epc_page(encl->secs.epc_page, SGX_EPC_PAGE_ENCLAVE);

/* Set only after completion, as encl->lock has not been taken. */
set_bit(SGX_ENCL_CREATED, &encl->flags);
@@ -325,7 +325,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
goto err_out;
}

- sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_RECLAIMER_TRACKED);
+ sgx_record_epc_page(encl_page->epc_page, SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE);
mutex_unlock(&encl->lock);
mmap_read_unlock(current->mm);
return ret;
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 085c06fdc359..3c0d33b72896 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -304,6 +304,8 @@ static void sgx_reclaim_pages(void)
epc_page = list_first_entry(&sgx_global_lru.reclaimable,
struct sgx_epc_page, list);
encl_page = epc_page->owner;
+ if (WARN_ON_ONCE(!(epc_page->flags & SGX_EPC_PAGE_ENCLAVE)))
+ continue;

if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
@@ -360,8 +362,7 @@ static void sgx_reclaim_pages(void)
sgx_reclaimer_write(epc_page, &backing[i++]);

kref_put(&encl_page->encl->refcount, sgx_encl_release);
- epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
- SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
+ epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;

sgx_free_epc_page(epc_page);
}
@@ -496,6 +497,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
/**
* sgx_record_epc_page() - Add a page to the LRU tracking
* @page: EPC page
+ * @flags: Reclaim flags for the page.
*
* Mark a page with the specified flags and add it to the appropriate
* (un)reclaimable list.
@@ -525,18 +527,16 @@ void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
int sgx_drop_epc_page(struct sgx_epc_page *page)
{
spin_lock(&sgx_global_lru.lock);
- if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
- /* The page is being reclaimed. */
- if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
- spin_unlock(&sgx_global_lru.lock);
- return -EBUSY;
- }
-
- page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+ if ((page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) &&
+ (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)) {
+ spin_unlock(&sgx_global_lru.lock);
+ return -EBUSY;
}
list_del(&page->list);
spin_unlock(&sgx_global_lru.lock);

+ page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;
+
return 0;
}

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 284d0cda9e36..76eae4ecbf87 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -31,8 +31,14 @@

/* page flag to indicate reclaim is in progress */
#define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(2)
+#define SGX_EPC_PAGE_ENCLAVE BIT(3)
+#define SGX_EPC_PAGE_VERSION_ARRAY BIT(4)
+#define SGX_EPC_PAGE_ENCLAVE_RECLAIMABLE (SGX_EPC_PAGE_ENCLAVE | \
+ SGX_EPC_PAGE_RECLAIMER_TRACKED)
#define SGX_EPC_PAGE_RECLAIM_FLAGS (SGX_EPC_PAGE_RECLAIMER_TRACKED | \
- SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
+ SGX_EPC_PAGE_RECLAIM_IN_PROGRESS | \
+ SGX_EPC_PAGE_ENCLAVE | \
+ SGX_EPC_PAGE_VERSION_ARRAY)

struct sgx_epc_page {
unsigned int section;
--
2.37.3