linux-kernel - [PATCH 1/4] x86/sgx: Add total number of EPC pages

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Message-ID: <20250321123938.802763-2-elena.reshetova@intel.com>
Date: Fri, 21 Mar 2025 14:34:40 +0200
From: Elena Reshetova <elena.reshetova@...el.com>
To: dave.hansen@...el.com
Cc: jarkko@...nel.org,
	linux-sgx@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	asit.k.mallick@...el.com,
	vincent.r.scarlata@...el.com,
	chongc@...gle.com,
	erdemaktas@...gle.com,
	vannapurve@...gle.com,
	dionnaglaze@...gle.com,
	bondarn@...gle.com,
	scott.raynor@...el.com,
	Elena Reshetova <elena.reshetova@...el.com>
Subject: [PATCH 1/4] x86/sgx: Add total number of EPC pages

In order to successfully execute ENCLS[EUPDATESVN], EPC must be empty.
SGX already has a variable sgx_nr_free_pages that tracks free
EPC pages. Add a new variable, sgx_nr_total_pages, that will keep
track of total number of EPC pages. It will be used in subsequent
patch to change the sgx_nr_free_pages into sgx_nr_used_pages and
allow an easy check for an empty EPC.

Note: The serialization for sgx_nr_total_pages is not needed because
the variable is only updated during the initialization and there's no
concurrent access.

Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 8ce352fc72ac..d5df67dab247 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -33,6 +33,7 @@ static LIST_HEAD(sgx_active_page_list);
 static DEFINE_SPINLOCK(sgx_reclaimer_lock);
 
 static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
+static unsigned long sgx_nr_total_pages;
 
 /* Nodes with one or more EPC sections. */
 static nodemask_t sgx_numa_mask;
@@ -648,6 +649,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
 	}
 
+	sgx_nr_total_pages += nr_pages;
+
 	return true;
 }
 
-- 
2.45.2