linux-kernel - [RFC PATCH 10/20] x86/sgx: Return the number of EPC pages that were successfully reclaimed

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Date:   Thu, 22 Sep 2022 10:10:47 -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 10/20] x86/sgx: Return the number of EPC pages that were successfully reclaimed

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

Return the number of reclaimed pages from sgx_reclaim_pages(), the EPC
cgroup will use the result to track the success rate of its reclaim
calls, e.g. to escalate to a more forceful reclaiming mode if necessary.

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 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 0010ed1b2e98..fc5aed813834 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -290,8 +290,10 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page,
  * + EWB) but not sufficiently. Reclaiming one page at a time would also be
  * problematic as it would increase the lock contention too much, which would
  * halt forward progress.
+ *
+ * Return: number of EPC pages reclaimed
  */
-static void sgx_reclaim_pages(int nr_to_scan)
+static int sgx_reclaim_pages(int nr_to_scan)
 {
 	struct sgx_backing backing[SGX_MAX_NR_TO_RECLAIM];
 	struct sgx_encl_page *encl_page;
@@ -373,6 +375,7 @@ static void sgx_reclaim_pages(int nr_to_scan)
 	}
 out:
 	cond_resched();
+	return i;
 }
 
 static bool sgx_should_reclaim(unsigned long watermark)
-- 
2.37.3