linux-kernel - Re: [PATCH 5.12 237/242] drm/ast: Remove reference to struct drm

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Message-ID: <CAJn8CcF+gfXToErpZv=pWmBKF-i--oVWmaM=6AQ8YZCb21X=oA@mail.gmail.com>
Date:   Mon, 19 Jul 2021 17:57:30 +0800
From:   Xiaotian Feng <xtfeng@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org, Thomas Zimmermann <tzimmermann@...e.de>,
        "Michael J. Ruhl" <michael.j.ruhl@...el.com>,
        KuoHsiang Chou <kuohsiang_chou@...eedtech.com>,
        kernel test robot <lkp@...el.com>,
        Dave Airlie <airlied@...hat.com>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 5.12 237/242] drm/ast: Remove reference to struct drm_device.pdev

On Fri, Jul 16, 2021 at 5:13 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> From: Thomas Zimmermann <tzimmermann@...e.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@...e.de>
> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@...el.com>
> Fixes: ba4e0339a6a3 ("drm/ast: Fixed CVE for DP501")
> Cc: KuoHsiang Chou <kuohsiang_chou@...eedtech.com>
> Cc: kernel test robot <lkp@...el.com>
> Cc: Thomas Zimmermann <tzimmermann@...e.de>
> Cc: Dave Airlie <airlied@...hat.com>
> Cc: dri-devel@...ts.freedesktop.org
> Link: https://patchwork.freedesktop.org/patch/msgid/20210429105101.25667-2-tzimmermann@suse.de
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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