linux-kernel - Re: [PATCH 3/3] x86/PCI: Preserve host bridge windows completely covered by E820

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Message-ID: <b41cfd4d-3f55-168a-e96c-cf2d11d50f28@redhat.com>
Date:   Thu, 10 Mar 2022 13:28:38 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Myron Stowe <myron.stowe@...hat.com>,
        Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>,
        Benoit Grégoire <benoitg@...us.ca>,
        Hui Wang <hui.wang@...onical.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>, wse@...edocomputers.com
Subject: Re: [PATCH 3/3] x86/PCI: Preserve host bridge windows completely
 covered by E820

Hi Bjorn,

On 3/9/22 19:15, Bjorn Helgaas wrote:
> On Sat, Mar 05, 2022 at 11:37:23AM +0100, Hans de Goede wrote:
>> On 3/4/22 16:46, Hans de Goede wrote:
>>> On 3/4/22 16:32, Bjorn Helgaas wrote:
>>>> On Fri, Mar 04, 2022 at 03:16:42PM +0100, Hans de Goede wrote:
>>>>> On 3/4/22 04:51, Bjorn Helgaas wrote:
>>>>>> From: Bjorn Helgaas <bhelgaas@...gle.com>
>>>>>>
>>>>>> Many folks have reported PCI devices not working.  It could affect any
>>>>>> device, but most reports are for Thunderbolt controllers on Lenovo Yoga and
>>>>>> Clevo Barebone laptops and the touchpad on Lenovo IdeaPads.
>>>>>> ...
> 
>>>>>> diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c
>>>>>> index 7378ea146976..405f0af53e3d 100644
>>>>>> --- a/arch/x86/kernel/resource.c
>>>>>> +++ b/arch/x86/kernel/resource.c
>>>>>> @@ -39,6 +39,17 @@ void remove_e820_regions(struct device *dev, struct resource *avail)
>>>>>>  		e820_start = entry->addr;
>>>>>>  		e820_end = entry->addr + entry->size - 1;
>>>>>>  
>>>>>> +		/*
>>>>>> +		 * If an E820 entry covers just part of the resource, we
>>>>>> +		 * assume E820 is telling us about something like host
>>>>>> +		 * bridge register space that is unavailable for PCI
>>>>>> +		 * devices.  But if it covers the *entire* resource, it's
>>>>>> +		 * more likely just telling us that this is MMIO space, and
>>>>>> +		 * that doesn't need to be removed.
>>>>>> +		 */
>>>>>> +		if (e820_start <= avail->start && avail->end <= e820_end)
>>>>>> +			continue;
>>>>>> +
>>>>>
>>>>> IMHO it would be good to add some logging here, since hitting this is
>>>>> somewhat of a special case. For the Fedora test kernels I did I changed
>>>>> this to:
>>>>>
>>>>> 		if (e820_start <= avail->start && avail->end <= e820_end) {
>>>>> 			dev_info(dev, "resource %pR fully covered by e820 entry [mem %#010Lx-%#010Lx]\n",
>>>>> 				 avail, e820_start, e820_end);
>>>>> 			continue;
>>>>> 		}
>>>>>
>>>>> And I expect/hope to see this new info message on the ideapad with the
>>>>> touchpad issue.
> 
> I added this logging.
> 
>> So I just got the first report back from the Fedora test 5.16.12 kernel
>> with this series added. Good news on the ideapad this wotks fine to
>> fix the touchpad issue (as expected).
> 
> Any "Tested-by" I could add?  If we can, I'd really like to give some
> credit to the folks who suffered through this and helped resolve it.

Good point, the reporter of:
https://bugzilla.redhat.com/show_bug.cgi?id=1868899

has done most of the ideapad with touchpad issues testing for me
and has been very helpful. I agree he deserves credit for this.

I've asked him if he is ok with adding a Tested-by tag and if yes,
which email we should use.

Regards,

Hans