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@redhat.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@amd.com>
Link: https://lore.kernel.org/r/20240217015642.113806-1-mario.limonciello@amd.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x86/amd/pmf/tee-if.c
index 4f74de680654ac04ceef853cbcff6f9be172bd02..8527dca9cf5604dc140ac22c5f06870bd32be296 100644 (file)
--- 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: