linux-kernel - Re: [PATCH AUTOSEL 6.14 107/642] drm/amdgpu: adjust drm_firmware_drivers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <0e8a1005-baa6-493e-a514-cd5d806949e1@suse.de>
Date: Thu, 21 Aug 2025 11:32:54 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Cc: Alex Deucher <alexander.deucher@....com>,
 Kent Russell <kent.russell@....com>, christian.koenig@....com,
 airlied@...il.com, simona@...ll.ch, lijo.lazar@....com,
 mario.limonciello@....com, rajneesh.bhardwaj@....com, kenneth.feng@....com,
 Ramesh.Errabolu@....com, amd-gfx@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH AUTOSEL 6.14 107/642] drm/amdgpu: adjust
 drm_firmware_drivers_only() handling

Hi

Am 06.05.25 um 00:05 schrieb Sasha Levin:
> From: Alex Deucher <alexander.deucher@....com>
>
> [ Upstream commit e00e5c223878a60e391e5422d173c3382d378f87 ]
>
> Move to probe so we can check the PCI device type and
> only apply the drm_firmware_drivers_only() check for
> PCI DISPLAY classes.  Also add a module parameter to
> override the nomodeset kernel parameter as a workaround
> for platforms that have this hardcoded on their kernel
> command lines.

I just came across this patch because it got backported into various 
older releases. It was part of the series at [1]. From the cover letter:

 >>>

There are a number of systems and cloud providers out there
that have nomodeset hardcoded in their kernel parameters
to block nouveau for the nvidia driver.  This prevents the
amdgpu driver from loading. Unfortunately the end user cannot
easily change this.  The preferred way to block modules from
loading is to use modprobe.blacklist=<driver>.  That is what
providers should be using to block specific drivers.

Drop the check to allow the driver to load even when nomodeset
is specified on the kernel command line.

<<<

Why was that series never on dri-devel?

Why is this necessary in the upstream kernel? It works around a problem 
with the user's configuration. The series' cover letter already states 
the correct solution.

Firmware-only parameters affect all drivers; why not try for a common 
solution? At least the test against the PCI class appears useful in the 
common case.

Best regards
Thomas


>
> Reviewed-by: Kent Russell <kent.russell@....com>
> Signed-off-by: Alex Deucher <alexander.deucher@....com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index f2d77bc04e4a9..7246c54bd2bbf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -173,6 +173,7 @@ uint amdgpu_sdma_phase_quantum = 32;
>   char *amdgpu_disable_cu;
>   char *amdgpu_virtual_display;
>   bool enforce_isolation;
> +int amdgpu_modeset = -1;
>   
>   /* Specifies the default granularity for SVM, used in buffer
>    * migration and restoration of backing memory when handling
> @@ -1033,6 +1034,13 @@ module_param_named(user_partt_mode, amdgpu_user_partt_mode, uint, 0444);
>   module_param(enforce_isolation, bool, 0444);
>   MODULE_PARM_DESC(enforce_isolation, "enforce process isolation between graphics and compute . enforce_isolation = on");
>   
> +/**
> + * DOC: modeset (int)
> + * Override nomodeset (1 = override, -1 = auto). The default is -1 (auto).
> + */
> +MODULE_PARM_DESC(modeset, "Override nomodeset (1 = enable, -1 = auto)");
> +module_param_named(modeset, amdgpu_modeset, int, 0444);
> +
>   /**
>    * DOC: seamless (int)
>    * Seamless boot will keep the image on the screen during the boot process.
> @@ -2244,6 +2252,12 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
>   	int ret, retry = 0, i;
>   	bool supports_atomic = false;
>   
> +	if ((pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA ||
> +	    (pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER) {
> +		if (drm_firmware_drivers_only() && amdgpu_modeset == -1)
> +			return -EINVAL;
> +	}
> +
>   	/* skip devices which are owned by radeon */
>   	for (i = 0; i < ARRAY_SIZE(amdgpu_unsupported_pciidlist); i++) {
>   		if (amdgpu_unsupported_pciidlist[i] == pdev->device)

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)