linux-kernel - [RFC PATCH 12/20] x86/sgx: Add helper to retrieve SGX EPC LRU given an EPC page

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Message-Id: <20220922171057.1236139-13-kristen@linux.intel.com>
Date:   Thu, 22 Sep 2022 10:10:49 -0700
From:   Kristen Carlson Accardi <kristen@...ux.intel.com>
To:     linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org,
        cgroups@...r.kernel.org, Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>
Cc:     Kristen Carlson Accardi <kristen@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [RFC PATCH 12/20] x86/sgx: Add helper to retrieve SGX EPC LRU given an EPC page

From: Sean Christopherson <sean.j.christopherson@...el.com>

Introduce a function that will be used to retrieve an LRU
from an EPC page.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 98531f6fb448..9f2cb264a347 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -31,6 +31,10 @@ static DEFINE_XARRAY(sgx_epc_address_space);
  * with sgx_global_lru.lock acquired.
  */
 static struct sgx_epc_lru sgx_global_lru;
+static inline struct sgx_epc_lru *sgx_lru(struct sgx_epc_page *epc_page)
+{
+	return &sgx_global_lru;
+}
 
 static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
 
@@ -299,6 +303,7 @@ static int sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_encl_page *encl_page;
 	struct sgx_epc_page *epc_page, *tmp;
+	struct sgx_epc_lru *lru;
 	pgoff_t page_index;
 	LIST_HEAD(iso);
 	int ret;
@@ -354,10 +359,11 @@ static int sgx_reclaim_pages(int nr_to_scan, bool ignore_age)
 		continue;
 
 skip:
-		spin_lock(&sgx_global_lru.lock);
+		lru = sgx_lru(epc_page);
+		spin_lock(&lru->lock);
 		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
-		list_move_tail(&epc_page->list, &sgx_global_lru.reclaimable);
-		spin_unlock(&sgx_global_lru.lock);
+		list_move_tail(&epc_page->list, &lru->reclaimable);
+		spin_unlock(&lru->lock);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
 	}
@@ -514,14 +520,16 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
  */
 void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
-	spin_lock(&sgx_global_lru.lock);
+	struct sgx_epc_lru *lru = sgx_lru(page);
+
+	spin_lock(&lru->lock);
 	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);
 	page->flags |= flags;
 	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
-		list_add_tail(&page->list, &sgx_global_lru.reclaimable);
+		list_add_tail(&page->list, &lru->reclaimable);
 	else
-		list_add_tail(&page->list, &sgx_global_lru.unreclaimable);
-	spin_unlock(&sgx_global_lru.lock);
+		list_add_tail(&page->list, &lru->unreclaimable);
+	spin_unlock(&lru->lock);
 }
 
 /**
@@ -536,14 +544,16 @@ 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);
+	struct sgx_epc_lru *lru = sgx_lru(page);
+
+	spin_lock(&lru->lock);
 	if ((page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) &&
 	    (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)) {
-		spin_unlock(&sgx_global_lru.lock);
+		spin_unlock(&lru->lock);
 		return -EBUSY;
 	}
 	list_del(&page->list);
-	spin_unlock(&sgx_global_lru.lock);
+	spin_unlock(&lru->lock);
 
 	page->flags &= ~SGX_EPC_PAGE_RECLAIM_FLAGS;
 
-- 
2.37.3