linux-kernel - [PATCH] platform/x86/amd/pmf: Fix a potential race with policy binary sideload

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Message-ID: <20240217015642.113806-1-mario.limonciello@amd.com>
Date: Fri, 16 Feb 2024 19:56:42 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: <Shyam-sundar.S-k@....com>, <hdegoede@...hat.com>
CC: <platform-driver-x86@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH] platform/x86/amd/pmf: Fix a potential race with policy binary sideload

The debugfs `update_policy` file is created before
amd_pmf_start_policy_engine() has completed, and thus there could be
a possible (albeit unlikely) race between sideloading a policy and the
BIOS policy getting setup.

Move the debugfs file creation after all BIOS policy is setup.

Fixes: 10817f28e533 ("platform/x86/amd/pmf: Add capability to sideload of policy binary")
Reported-by: Hans de Goede <hdegoede@...hat.com>
Closes: https://lore.kernel.org/platform-driver-x86/15df7d02-b0aa-457a-954a-9d280a592843@redhat.com/T/#m2c445f135e5ef9b53184be7fc9df84e15f89d4d9
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 drivers/platform/x86/amd/pmf/tee-if.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
index 4f74de680654..8527dca9cf56 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -456,8 +456,6 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
 	memcpy(dev->policy_buf, dev->policy_base, dev->policy_sz);
 
 	amd_pmf_hex_dump_pb(dev);
-	if (pb_side_load)
-		amd_pmf_open_pb(dev, dev->dbgfs_dir);
 
 	dev->prev_data = kzalloc(sizeof(*dev->prev_data), GFP_KERNEL);
 	if (!dev->prev_data)
@@ -467,6 +465,9 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
 	if (ret)
 		goto error;
 
+	if (pb_side_load)
+		amd_pmf_open_pb(dev, dev->dbgfs_dir);
+
 	return 0;
 
 error:
-- 
2.34.1