linux-kernel - [PATCH 5/6] bus: fsl-mc: move uapi misc dev create/remove in probe and remove

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Message-Id: <20220208145928.12468-6-laurentiu.tudor@nxp.com>
Date:   Tue,  8 Feb 2022 16:59:27 +0200
From:   laurentiu.tudor@....com
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     ioana.ciornei@....com, diana.craciun@....nxp.com,
        jon@...id-run.com, Laurentiu Tudor <laurentiu.tudor@....com>
Subject: [PATCH 5/6] bus: fsl-mc: move uapi misc dev create/remove in probe and remove

From: Laurentiu Tudor <laurentiu.tudor@....com>

When devices are owned by VFIO lets not allow user-space to play with
them through the restool management interface thus breaking isolation.
Drop restool misc device creation and destruction from the common
dprc_setup() and dprc_cleanup() functions (shared with fsl-mc VFIO)
and open code it drpc driver's probe and remove ops.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@....com>
---
 drivers/bus/fsl-mc/dprc-driver.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/bus/fsl-mc/dprc-driver.c b/drivers/bus/fsl-mc/dprc-driver.c
index 8482c4fca835..82bf3fe09273 100644
--- a/drivers/bus/fsl-mc/dprc-driver.c
+++ b/drivers/bus/fsl-mc/dprc-driver.c
@@ -618,7 +618,6 @@ int dprc_setup(struct fsl_mc_device *mc_dev)
 	struct irq_domain *mc_msi_domain;
 	bool mc_io_created = false;
 	bool msi_domain_set = false;
-	bool uapi_created = false;
 	u16 major_ver, minor_ver;
 	size_t region_size;
 	int error;
@@ -651,11 +650,6 @@ int dprc_setup(struct fsl_mc_device *mc_dev)
 			return error;
 
 		mc_io_created = true;
-	} else {
-		error = fsl_mc_uapi_create_device_file(mc_bus);
-		if (error < 0)
-			return -EPROBE_DEFER;
-		uapi_created = true;
 	}
 
 	mc_msi_domain = fsl_mc_find_msi_domain(&mc_dev->dev);
@@ -713,9 +707,6 @@ int dprc_setup(struct fsl_mc_device *mc_dev)
 		mc_dev->mc_io = NULL;
 	}
 
-	if (uapi_created)
-		fsl_mc_uapi_remove_device_file(mc_bus);
-
 	return error;
 }
 EXPORT_SYMBOL_GPL(dprc_setup);
@@ -734,9 +725,15 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 {
 	int error;
 
+	if (fsl_mc_is_root_dprc(&mc_dev->dev)) {
+		error = fsl_mc_uapi_create_device_file(to_fsl_mc_bus(mc_dev));
+		if (error < 0)
+			return -EPROBE_DEFER;
+	}
+
 	error = dprc_setup(mc_dev);
 	if (error < 0)
-		return error;
+		goto uapi_cleanup;
 
 	/*
 	 * Discover MC objects in DPRC object:
@@ -759,6 +756,10 @@ static int dprc_probe(struct fsl_mc_device *mc_dev)
 	device_for_each_child(&mc_dev->dev, NULL, __fsl_mc_device_remove);
 dprc_cleanup:
 	dprc_cleanup(mc_dev);
+uapi_cleanup:
+	if (fsl_mc_is_root_dprc(&mc_dev->dev))
+		fsl_mc_uapi_remove_device_file(to_fsl_mc_bus(mc_dev));
+
 	return error;
 }
 
@@ -792,7 +793,6 @@ static void dprc_teardown_irq(struct fsl_mc_device *mc_dev)
 
 int dprc_cleanup(struct fsl_mc_device *mc_dev)
 {
-	struct fsl_mc_bus *mc_bus = to_fsl_mc_bus(mc_dev);
 	int error;
 
 	/* this function should be called only for DPRCs, it
@@ -821,8 +821,6 @@ int dprc_cleanup(struct fsl_mc_device *mc_dev)
 	if (!fsl_mc_is_root_dprc(&mc_dev->dev)) {
 		fsl_destroy_mc_io(mc_dev->mc_io);
 		mc_dev->mc_io = NULL;
-	} else {
-		fsl_mc_uapi_remove_device_file(mc_bus);
 	}
 
 	return 0;
@@ -854,6 +852,9 @@ static int dprc_remove(struct fsl_mc_device *mc_dev)
 
 	device_for_each_child(&mc_dev->dev, NULL, __fsl_mc_device_remove);
 
+	if (fsl_mc_is_root_dprc(&mc_dev->dev))
+		fsl_mc_uapi_remove_device_file(to_fsl_mc_bus(mc_dev));
+
 	dprc_cleanup(mc_dev);
 
 	dev_info(&mc_dev->dev, "DPRC device unbound from driver");
-- 
2.17.1