From 3312bb4ad09ca6423bd4a5b15a94588a8962fb8e Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Thu, 4 May 2023 13:35:08 +0300
Subject: [PATCH] drm/i915: taint kernel when force probing unsupported devices
For development and testing purposes, the i915.force_probe module
parameter and DRM_I915_FORCE_PROBE kconfig option allow probing of
devices that aren't supported by the driver.
The i915.force_probe module parameter is "unsafe" and setting it taints
the kernel. However, using the kconfig option does not.
Always taint the kernel when force probing a device that is not
supported.
v2: Drop "depends on EXPERT" to avoid build breakage (kernel test robot)
Fixes: 7ef5ef5cdead ("drm/i915: add force_probe module parameter to replace alpha_support")
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230504103508.1818540-1-jani.nikula@intel.com
---
drivers/gpu/drm/i915/Kconfig | 12 +++++++-----
drivers/gpu/drm/i915/i915_pci.c | 6 ++++++
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 06a0ca157e89e..e4f4d2e3fdfeb 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -62,10 +62,11 @@ config DRM_I915_FORCE_PROBE
This is the default value for the i915.force_probe module
parameter. Using the module parameter overrides this option.
- Force probe the i915 for Intel graphics devices that are
- recognized but not properly supported by this kernel version. It is
- recommended to upgrade to a kernel version with proper support as soon
- as it is available.
+ Force probe the i915 driver for Intel graphics devices that are
+ recognized but not properly supported by this kernel version. Force
+ probing an unsupported device taints the kernel. It is recommended to
+ upgrade to a kernel version with proper support as soon as it is
+ available.
It can also be used to block the probe of recognized and fully
supported devices.
@@ -75,7 +76,8 @@ config DRM_I915_FORCE_PROBE
Use "<pci-id>[,<pci-id>,...]" to force probe the i915 for listed
devices. For example, "4500" or "4500,4571".
- Use "*" to force probe the driver for all known devices.
+ Use "*" to force probe the driver for all known devices. Not
+ recommended.
Use "!" right before the ID to block the probe of the device. For
example, "4500,!4571" forces the probe of 4500 and blocks the probe of
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index 6b5c119a7d829..ccc315782d22b 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -1345,6 +1345,12 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
return -ENODEV;
}
+ if (intel_info->require_force_probe) {
+ dev_info(&pdev->dev, "Force probing unsupported Device ID %04x, tainting kernel\n",
+ pdev->device);
+ add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+ }
+
/* Only bind to function 0 of the device. Early generations
* used function 1 as a placeholder for multi-head. This causes
* us confusion instead, especially on the systems where both
--
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