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References: <20231016040132.23824-1-kai.heng.feng@canonical.com> <20231016093210.GA22952@wunner.de>
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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
Date:   Tue, 17 Oct 2023 12:35:18 +0800
Message-ID: <CAAd53p7gbWSkRbng205z2U0_kU42JeFw8qThcBuXuVwCC+Y_VQ@mail.gmail.com>
Subject: Re: [PATCH] PCI: pciehp: Prevent child devices from doing RPM on PCIe
 Link Down
To:     Lukas Wunner <lukas@wunner.de>
Cc:     bhelgaas@google.com, linux-pm@vger.kernel.org,
        linux-mmc@vger.kernel.org, Ricky Wu <ricky_wu@realtek.com>,
        Kees Cook <keescook@chromium.org>,
        Tony Luck <tony.luck@intel.com>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org, bpf@vger.kernel.org
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On Mon, Oct 16, 2023 at 5:32=E2=80=AFPM Lukas Wunner <lukas@wunner.de> wrot=
e:
>
> On Mon, Oct 16, 2023 at 12:01:31PM +0800, Kai-Heng Feng wrote:
> > When inserting an SD7.0 card to Realtek card reader, it can trigger PCI
> > slot Link down and causes the following error:
>
> Why does *inserting* a card cause a Link Down?

Ricky, do you know the reason why Link Down happens?

>
>
> > [   63.898861] pcieport 0000:00:1c.0: pciehp: Slot(8): Link Down
> > [   63.912118] BUG: unable to handle page fault for address: ffffb24d40=
3e5010
> [...]
> > [   63.912198]  ? asm_exc_page_fault+0x27/0x30
> > [   63.912203]  ? ioread32+0x2e/0x70
> > [   63.912206]  ? rtsx_pci_write_register+0x5b/0x90 [rtsx_pci]
> > [   63.912217]  rtsx_set_l1off_sub+0x1c/0x30 [rtsx_pci]
> > [   63.912226]  rts5261_set_l1off_cfg_sub_d0+0x36/0x40 [rtsx_pci]
> > [   63.912234]  rtsx_pci_runtime_idle+0xc7/0x160 [rtsx_pci]
> > [   63.912243]  ? __pfx_pci_pm_runtime_idle+0x10/0x10
> > [   63.912246]  pci_pm_runtime_idle+0x34/0x70
> > [   63.912248]  rpm_idle+0xc4/0x2b0
> > [   63.912251]  pm_runtime_work+0x93/0xc0
> > [   63.912254]  process_one_work+0x21a/0x430
> > [   63.912258]  worker_thread+0x4a/0x3c0
>
> This looks like pcr->remap_addr is accessed after it has been iounmap'ed
> in rtsx_pci_remove() or before it has been iomap'ed in rtsx_pci_probe().
>
> Is the card reader itself located below a hotplug port and unplugged here=
?
> Or is this about the card being removed from the card reader?
>
> Having full dmesg output and lspci -vvv output attached to a bugzilla
> would help to understand what is going on.

I don't have the hardware so we need Ricky to provide more information here=
.

Regardless of the cardreader issue, do you have any concern on the patch it=
self?

Kai-Heng

>
> Thanks,
>
> Lukas