[PATCH v2 10/16] platform/x86/amd/pmf: Add capability to sideload of policy binary

[Shyam Sundar S K]

A policy binary is OS agnostic, and the same policies are expected to work
across the OSes.  At times it becomes difficult to debug when the policies
inside the policy binaries starts to misbehave. Add a way to sideload such
policies independently to debug them via a debugfs entry.

Reported-by: kernel test robot <lkp at intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309251031.awDDkRgS-lkp@intel.com/
Reviewed-by: Mario Limonciello <mario.limonciello at amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k at amd.com>
---
 drivers/platform/x86/amd/pmf/pmf.h    |  1 +
 drivers/platform/x86/amd/pmf/tee-if.c | 68 +++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/drivers/platform/x86/amd/pmf/pmf.h b/drivers/platform/x86/amd/pmf/pmf.h
index 2ad5ece47601..b862cd4f902e 100644
--- a/drivers/platform/x86/amd/pmf/pmf.h
+++ b/drivers/platform/x86/amd/pmf/pmf.h
@@ -218,6 +218,7 @@ struct amd_pmf_dev {
 	bool cnqf_supported;
 	struct notifier_block pwr_src_notifier;
 	/* Smart PC solution builder */
+	struct dentry *esbin;
 	unsigned char *policy_buf;
 	u32 policy_sz;
 	struct tee_context *tee_ctx;
diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
index b0711b2f8c8f..01f974b55a6a 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -8,6 +8,7 @@
  * Author: Shyam Sundar S K <Shyam-sundar.S-k at amd.com>
  */
 
+#include <linux/debugfs.h>
 #include <linux/tee_drv.h>
 #include <linux/uuid.h>
 #include "pmf.h"
@@ -16,9 +17,15 @@
 
 /* Policy binary actions sampling frequency (in ms) */
 static int pb_actions_ms = 1000;
+/* Sideload policy binaries to debug policy failures */
+static bool pb_side_load;
+
 #ifdef CONFIG_AMD_PMF_DEBUG
 module_param(pb_actions_ms, int, 0644);
 MODULE_PARM_DESC(pb_actions_ms, "Policy binary actions sampling frequency (default = 1000ms)");
+
+module_param(pb_side_load, bool, 0444);
+MODULE_PARM_DESC(pb_side_load, "Sideload policy binaries debug policy failures");
 #endif
 
 static const uuid_t amd_pmf_ta_uuid = UUID_INIT(0x6fd93b77, 0x3fb8, 0x524d,
@@ -268,6 +275,61 @@ static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
 	return 0;
 }
 
+#ifdef CONFIG_AMD_PMF_DEBUG
+static ssize_t amd_pmf_get_pb_data(struct file *filp, const char __user *buf,
+				   size_t length, loff_t *pos)
+{
+	struct amd_pmf_dev *dev = filp->private_data;
+	int ret;
+
+	/* policy binary size cannot exceed POLICY_BUF_MAX_SZ */
+	if (length > POLICY_BUF_MAX_SZ || length == 0)
+		return -EINVAL;
+
+	dev->policy_sz = length;
+	if (copy_from_user(dev->policy_buf, buf, dev->policy_sz))
+		return -EFAULT;
+
+	ret = amd_pmf_start_policy_engine(dev);
+	if (ret)
+		return -EINVAL;
+
+	return length;
+}
+
+static const struct file_operations pb_fops = {
+	.write = amd_pmf_get_pb_data,
+	.open = simple_open,
+};
+
+static int amd_pmf_open_pb(struct amd_pmf_dev *dev, struct dentry *debugfs_root)
+{
+	struct dentry *file = NULL;
+
+	dev->esbin = debugfs_create_dir("pb", debugfs_root);
+	if (IS_ERR(dev->esbin))
+		return -EINVAL;
+
+	file = debugfs_create_file("update_policy", 0644, dev->esbin, dev, &pb_fops);
+	if (!file)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void amd_pmf_remove_pb(struct amd_pmf_dev *dev)
+{
+	debugfs_remove_recursive(dev->esbin);
+}
+#else
+static int amd_pmf_open_pb(struct amd_pmf_dev *dev, struct dentry *debugfs_root)
+{
+	return 0;
+}
+
+static void amd_pmf_remove_pb(struct amd_pmf_dev *dev) {}
+#endif
+
 static int amd_pmf_get_bios_buffer(struct amd_pmf_dev *dev)
 {
 	dev->policy_buf = kzalloc(dev->policy_sz, GFP_KERNEL);
@@ -280,6 +342,9 @@ static int amd_pmf_get_bios_buffer(struct amd_pmf_dev *dev)
 
 	memcpy(dev->policy_buf, dev->policy_base, dev->policy_sz);
 
+	if (pb_side_load)
+		amd_pmf_open_pb(dev, dev->dbgfs_dir);
+
 	return amd_pmf_start_policy_engine(dev);
 }
 
@@ -388,6 +453,9 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
 
 void amd_pmf_deinit_smart_pc(struct amd_pmf_dev *dev)
 {
+	if (pb_side_load)
+		amd_pmf_remove_pb(dev);
+
 	kfree(dev->prev_data);
 	kfree(dev->policy_buf);
 	cancel_delayed_work_sync(&dev->pb_work);
-- 
2.25.1