[PATCH v2 1/4] x86/sgx: Add /sys/kernel/debug/x86/sgx_total_mem

[Jarkko Sakkinen]

Create /sys/kernel/debug/x86/sgx_total_mem, after the driver is
initialized, describing the total amount of SGX reserved memory (also known
as Enclave Page Cache (EPC)) available in the system.

This can be used to implement stress that trigger the page reclaimer, and
it is probably useful information when admistering a system running
enclaves anyhow.

Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>

---

v2:
* sgx_nr_all_pages -> sgx_total_mem

 Documentation/x86/sgx.rst      |  6 ++++++
 arch/x86/kernel/cpu/sgx/main.c | 10 +++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/sgx.rst b/Documentation/x86/sgx.rst
index dd0ac96ff9ef..15bb8f4e42af 100644
--- a/Documentation/x86/sgx.rst
+++ b/Documentation/x86/sgx.rst
@@ -250,3 +250,9 @@ user wants to deploy SGX applications both on the host and in guests
 on the same machine, the user should reserve enough EPC (by taking out
 total virtual EPC size of all SGX VMs from the physical EPC size) for
 host SGX applications so they can run with acceptable performance.
+
+SGX debugging
+=============
+
+*/sys/kernel/debug/x86/sgx_total_mem* describes the total available
+SGX mwemory available in the system.
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de02bbcc..b65da19a53ee 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 /*  Copyright(c) 2016-20 Intel Corporation. */
 
+#include <linux/debugfs.h>
 #include <linux/file.h>
 #include <linux/freezer.h>
 #include <linux/highmem.h>
@@ -28,7 +29,10 @@ static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
 static LIST_HEAD(sgx_active_page_list);
 static DEFINE_SPINLOCK(sgx_reclaimer_lock);
 
-/* The free page list lock protected variables prepend the lock. */
+/* Total EPC memory available in bytes. */
+static unsigned long sgx_total_mem;
+
+/* The number of free EPC pages in all nodes. */
 static unsigned long sgx_nr_free_pages;
 
 /* Nodes with one or more EPC sections. */
@@ -656,6 +660,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
 	}
 
+	sgx_total_mem += nr_pages * PAGE_SIZE;
+
 	return true;
 }
 
@@ -823,6 +829,8 @@ static int __init sgx_init(void)
 	if (sgx_vepc_init() && ret)
 		goto err_provision;
 
+	debugfs_create_ulong("sgx_total_mem", 0444, arch_debugfs_dir, &sgx_total_mem);
+
 	return 0;
 
 err_provision:
-- 
2.32.0