Re: [PATCH 5.12 237/242] drm/ast: Remove reference to struct drm_device.pdev

Xiaotian Feng
2021-07-19T09:57:50Z

On Fri, Jul 16, 2021 at 5:13 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> From: Thomas Zimmermann <tzimmermann@suse.de>
>
> commit 0ecb51824e838372e01330752503ddf9c0430ef7 upstream.
>
> Using struct drm_device.pdev is deprecated. Upcast with to_pci_dev()
> from struct drm_device.dev to get the PCI device structure.
>
> v9:
> * fix remaining pdev references
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
> Fixes: ba4e0339a6a3 ("drm/ast: Fixed CVE for DP501")
> Cc: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
> Cc: kernel test robot <lkp@intel.com>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: dri-devel@lists.freedesktop.org
> Link: https://patchwork.freedesktop.org/patch/msgid/20210429105101.25667-2-tzimmermann@suse.de
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> drivers/gpu/drm/ast/ast_main.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> --- a/drivers/gpu/drm/ast/ast_main.c
> +++ b/drivers/gpu/drm/ast/ast_main.c
> @@ -411,7 +411,6 @@ struct ast_private *ast_device_create(co
> return ast;
> dev = &ast->base;
>
> - dev->pdev = pdev;
> pci_set_drvdata(pdev, dev);
>
> ast->regs = pcim_iomap(pdev, 1, 0);
> @@ -453,8 +452,8 @@ struct ast_private *ast_device_create(co
>
> /* map reserved buffer */
> ast->dp501_fw_buf = NULL;
> - if (dev->vram_mm->vram_size < pci_resource_len(dev->pdev, 0)) {
> - ast->dp501_fw_buf = pci_iomap_range(dev->pdev, 0, dev->vram_mm->vram_size, 0);
> + if (dev->vram_mm->vram_size < pci_resource_len(pdev, 0)) {
> + ast->dp501_fw_buf = pci_iomap_range(pdev, 0, dev->vram_mm->vram_size, 0);
> if (!ast->dp501_fw_buf)
> drm_info(dev, "failed to map reserved buffer!\n");
> }
>

Hi Greg,

This backport is incomplete for 5.10 kernel, kernel is panicked
on RIP: ast_device_create+0x7d. When I look into the crash code, I
found

struct ast_private *ast_device_create(struct drm_driver *drv,
struct pci_dev *pdev,
unsigned long flags)
{
.......
dev->pdev = pdev; // This is removed
pci_set_drvdata(pdev, dev);

ast->regs = pcim_iomap(pdev, 1, 0);
if (!ast->regs)
return ERR_PTR(-EIO);

/*
* If we don't have IO space at all, use MMIO now and
* assume the chip has MMIO enabled by default (rev 0x20
* and higher).
*/
if (!(pci_resource_flags(dev->pdev, 2) & IORESOURCE_IO)) { //
dev->pdev is in used here.
drm_info(dev, "platform has no IO space, trying MMIO\n");
ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
}

That's because commit 46fb883c3d0d8a823ef995ddb1f9b0817dea6882
is not backported to 5.10 kernel.

Best Regards
Xiaotian