[PATCH 2/2] x86/sgx: Add sgx_nr_{all, free}_pages to the debugfs

[Jarkko Sakkinen <jarkko@kernel.org>]

Add two debugs attributes:

* /sys/kernel/debug/x86/sgx_nr_all_pages
* /sys/kernel/debug/x86/sgx_nr_free_pages

These provide useful statistics for testing purposes.

E.g. on a NUC7CJYH2, when no enclaves are running, and EPC set to 32 MB:

$ sudo cat /sys/kernel/debug/x86/sgx_nr_all_pages
5632

$ sudo cat /sys/kernel/debug/x86/sgx_nr_free_pages
5632

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 arch/x86/kernel/cpu/sgx/main.c | 53 +++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 7df7048cb1c9..190c96735c9f 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/freezer.h>
 #include <linux/highmem.h>
 #include <linux/kthread.h>
@@ -25,7 +26,10 @@ 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. */
+/* The number of EPC pages in total in all nodes. */
+static unsigned long sgx_nr_all_pages;
+
+/* The number of free EPC pages in all nodes. */
 static unsigned long sgx_nr_free_pages;
 
 /* Nodes with one or more EPC sections. */
@@ -657,6 +661,8 @@ 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_all_pages += nr_pages;
+
 	return true;
 }
 
@@ -730,6 +736,44 @@ static bool __init sgx_page_cache_init(void)
 	return true;
 }
 
+#ifdef CONFIG_DEBUG_FS
+static ssize_t sgx_nr_all_pages_read(struct file *file, char __user *user_buf,
+				     size_t count, loff_t *pos)
+{
+	char kernel_buf[32];
+	int len;
+
+	len = snprintf(kernel_buf, sizeof(kernel_buf), "%lu\n", sgx_nr_all_pages);
+	if (len < 0)
+		return len;
+
+	return simple_read_from_buffer(user_buf, count, pos, kernel_buf, len);
+}
+
+static const struct file_operations sgx_nr_all_pages_fops = {
+	.read = sgx_nr_all_pages_read,
+	.llseek = default_llseek,
+};
+
+static ssize_t sgx_nr_free_pages_read(struct file *file, char __user *user_buf,
+				     size_t count, loff_t *pos)
+{
+	char kernel_buf[32];
+	int len;
+
+	len = snprintf(kernel_buf, sizeof(kernel_buf), "%lu\n", sgx_nr_free_pages);
+	if (len < 0)
+		return len;
+
+	return simple_read_from_buffer(user_buf, count, pos, kernel_buf, len);
+}
+
+static const struct file_operations sgx_nr_free_pages_fops = {
+	.read = sgx_nr_free_pages_read,
+	.llseek = default_llseek,
+};
+#endif /* CONFIG_DEBUG_FS */
+
 static int __init sgx_init(void)
 {
 	int ret;
@@ -750,6 +794,13 @@ static int __init sgx_init(void)
 	if (ret)
 		goto err_kthread;
 
+#ifdef CONFIG_DEBUG_FS
+	debugfs_create_file("sgx_nr_all_pages", 0400, arch_debugfs_dir, NULL,
+			    &sgx_nr_all_pages_fops);
+	debugfs_create_file("sgx_nr_free_pages", 0400, arch_debugfs_dir, NULL,
+			    &sgx_nr_free_pages_fops);
+#endif /* CONFIG_DEBUG_FS */
+
 	return 0;
 
 err_kthread:
-- 
2.31.1