linux-kernel - Re: [PATCH 8/9] drm/amdgpu: Remove driver side BAR release before resize

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: <20251110225455.GA2141964@bhelgaas>
Date: Mon, 10 Nov 2025 16:54:55 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>
Cc: Alex Bennée <alex.bennee@...aro.org>,
	Simon Richter <Simon.Richter@...yros.de>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	amd-gfx@...ts.freedesktop.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	David Airlie <airlied@...il.com>, dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	linux-pci@...r.kernel.org, Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Simona Vetter <simona@...ll.ch>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Michał Winiarski <michal.winiarski@...el.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/9] drm/amdgpu: Remove driver side BAR release before
 resize

amdgpu folks, any objection to this?

On Tue, Oct 28, 2025 at 07:35:50PM +0200, Ilpo Järvinen wrote:
> PCI core handles releasing device's resources and their rollback in
> case of failure of a BAR resizing operation. Releasing resource prior
> to calling pci_resize_resource() prevents PCI core from restoring the
> BARs as they were.
> 
> Remove driver-side release of BARs from the amdgpu driver.
> 
> Also remove the driver initiated assignment as pci_resize_resource()
> should try to assign as much as possible. If the driver side call
> manages to get more required resources assigned in some scenario, such
> a problem should be fixed inside pci_resize_resource() instead.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 7a899fb4de29..65474d365229 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1729,12 +1729,8 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>  	pci_write_config_word(adev->pdev, PCI_COMMAND,
>  			      cmd & ~PCI_COMMAND_MEMORY);
>  
> -	/* Free the VRAM and doorbell BAR, we most likely need to move both. */
> +	/* Tear down doorbell as resizing will release BARs */
>  	amdgpu_doorbell_fini(adev);
> -	if (adev->asic_type >= CHIP_BONAIRE)
> -		pci_release_resource(adev->pdev, 2);
> -
> -	pci_release_resource(adev->pdev, 0);
>  
>  	r = pci_resize_resource(adev->pdev, 0, rbar_size);
>  	if (r == -ENOSPC)
> @@ -1743,8 +1739,6 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>  	else if (r && r != -ENOTSUPP)
>  		dev_err(adev->dev, "Problem resizing BAR0 (%d).", r);
>  
> -	pci_assign_unassigned_bus_resources(adev->pdev->bus);
> -
>  	/* When the doorbell or fb BAR isn't available we have no chance of
>  	 * using the device.
>  	 */
> -- 
> 2.39.5
>