[PATCH for_v23 v2 6/9] x86/sgx: Split second half of sgx_free_page() to a separate helper

[Sean Christopherson <sean.j.christopherson@intel.com>]

Move the post-reclaim half of sgx_free_page() to a standalone helper so
that it can be used in flows where the page is known to be
non-reclaimable.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 44 ++++++++++++++++++++++++++--------
 arch/x86/kernel/cpu/sgx/sgx.h  |  1 +
 2 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 84a44251387b..e22cdbb431a3 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -103,6 +103,39 @@ struct sgx_epc_page *sgx_alloc_page(void *owner, bool reclaim)
 	return entry;
 }
 
+
+/**
+ * __sgx_free_page() - Free an EPC page
+ * @page:	pointer a previously allocated EPC page
+ *
+ * EREMOVE an EPC page and insert it back to the list of free pages. The page
+ * must not be reclaimable.
+ */
+void __sgx_free_page(struct sgx_epc_page *page)
+{
+	struct sgx_epc_section *section;
+	int ret;
+
+	/*
+	 * Don't take sgx_active_page_list_lock when asserting the page isn't
+	 * reclaimable, missing a WARN in the very rare case is preferable to
+	 * unnecessarily taking a global lock in the common case.
+	 */
+	WARN_ON_ONCE(page->desc & SGX_EPC_PAGE_RECLAIMABLE);
+
+	ret = __eremove(sgx_epc_addr(page));
+	if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret))
+		return;
+
+	section = sgx_epc_section(page);
+
+	spin_lock(&section->lock);
+	list_add_tail(&page->list, &section->page_list);
+	sgx_nr_free_pages++;
+	spin_unlock(&section->lock);
+
+}
+
 /**
  * sgx_free_page() - Free an EPC page
  * @page:	pointer a previously allocated EPC page
@@ -116,9 +149,6 @@ struct sgx_epc_page *sgx_alloc_page(void *owner, bool reclaim)
  */
 int sgx_free_page(struct sgx_epc_page *page)
 {
-	struct sgx_epc_section *section = sgx_epc_section(page);
-	int ret;
-
 	/*
 	 * Remove the page from the active list if necessary.  If the page
 	 * is actively being reclaimed, i.e. RECLAIMABLE is set but the
@@ -136,13 +166,7 @@ int sgx_free_page(struct sgx_epc_page *page)
 	}
 	spin_unlock(&sgx_active_page_list_lock);
 
-	ret = __eremove(sgx_epc_addr(page));
-	WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret);
-
-	spin_lock(&section->lock);
-	list_add_tail(&page->list, &section->page_list);
-	sgx_nr_free_pages++;
-	spin_unlock(&section->lock);
+	__sgx_free_page(page);
 
 	return 0;
 }
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 160a3c996ef6..87e375e8c25e 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -85,6 +85,7 @@ void sgx_reclaim_pages(void);
 
 struct sgx_epc_page *sgx_try_alloc_page(void);
 struct sgx_epc_page *sgx_alloc_page(void *owner, bool reclaim);
+void __sgx_free_page(struct sgx_epc_page *page);
 int sgx_free_page(struct sgx_epc_page *page);
 
 #endif /* _X86_SGX_H */
-- 
2.22.0