linux-kernel - Re: [PATCH v8 2/2] PCI/ACPI: Use device constraints instead of dates to opt devices into D3

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: <208afe43-2539-156b-971f-89233598b687@amd.com>
Date:   Thu, 3 Aug 2023 10:18:07 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Iain Lane <iain@...ngesquash.org.uk>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Subject: Re: [PATCH v8 2/2] PCI/ACPI: Use device constraints instead of dates
 to opt devices into D3

On 8/3/2023 10:14, Mika Westerberg wrote:
> On Thu, Aug 03, 2023 at 06:38:45AM -0500, Mario Limonciello wrote:
>> On 8/3/23 00:01, Mika Westerberg wrote:
>>> Hi,
>>>
>>> On Wed, Aug 02, 2023 at 03:10:13PM -0500, Mario Limonciello wrote:
>>>> @@ -3036,11 +3044,8 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>>>>    		if (dmi_check_system(bridge_d3_blacklist))
>>>>    			return false;
>>>> -		/*
>>>> -		 * It should be safe to put PCIe ports from 2015 or newer
>>>> -		 * to D3.
>>>> -		 */
>>>> -		if (dmi_get_bios_year() >= 2015)
>>>> +		/* the platform indicates in a device constraint that D3 is needed */
>>>> +		if (platform_constraint_d3(bridge))
>>>
>>> This for sure causes some sort of power regression on the Intel
>>> platforms made after 2015. Why not check for the constraint and:
>>>
>> Are you sure?  I saw it as an explanation of how Windows could put the
>> systems into D3 when there is no other PM related ACPI objects.
> 
> I'm concerned if there are no PEP constraints on some of the affected
> systems this now leaves root ports into D0 then, no?

Do you have any idea if any of the affected systems were something that 
didn't ship with Windows?  Like an Apple system or a Chromebook?

If so; I'd think it's better to treat those as "quirks" rather than make 
a blanket policy from the timing.