linux-kernel - Re: [RFC PATCH 1/3] pci, acpi: Match PCI config space accessors against platfrom specific ECAM quirks.

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]

Date:	Fri, 03 Jun 2016 09:57:40 -0700
From:	David Daney <ddaney.cavm@...il.com>
To:	Gabriele Paoloni <gabriele.paoloni@...wei.com>
CC:	Christopher Covington <cov@...eaurora.org>,
	Tomasz Nowicki <tn@...ihalf.com>,
	"helgaas@...nel.org" <helgaas@...nel.org>,
	"arnd@...db.de" <arnd@...db.de>,
	"will.deacon@....com" <will.deacon@....com>,
	"catalin.marinas@....com" <catalin.marinas@....com>,
	"rafael@...nel.org" <rafael@...nel.org>,
	"hanjun.guo@...aro.org" <hanjun.guo@...aro.org>,
	"Lorenzo.Pieralisi@....com" <Lorenzo.Pieralisi@....com>,
	"okaya@...eaurora.org" <okaya@...eaurora.org>,
	"jchandra@...adcom.com" <jchandra@...adcom.com>,
	"liudongdong (C)" <liudongdong3@...wei.com>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	"jcm@...hat.com" <jcm@...hat.com>,
	"dhdang@....com" <dhdang@....com>,
	"Liviu.Dudau@....com" <Liviu.Dudau@....com>,
	"ddaney@...iumnetworks.com" <ddaney@...iumnetworks.com>,
	"jeremy.linton@....com" <jeremy.linton@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"robert.richter@...iumnetworks.com" 
	<robert.richter@...iumnetworks.com>,
	"msalter@...hat.com" <msalter@...hat.com>,
	"Suravee.Suthikulpanit@....com" <Suravee.Suthikulpanit@....com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Wangyijing <wangyijing@...wei.com>,
	"mw@...ihalf.com" <mw@...ihalf.com>,
	"andrea.gallo@...aro.org" <andrea.gallo@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH 1/3] pci, acpi: Match PCI config space accessors against
 platfrom specific ECAM quirks.

On 06/03/2016 08:32 AM, Gabriele Paoloni wrote:
[...]
>>> +struct pci_ecam_ops *pci_mcfg_get_ops(struct acpi_pci_root *root)
>>> +{
>>> +	int bus_num = root->secondary.start;
>>> +	int domain = root->segment;
>>> +	struct pci_cfg_fixup *f;
>>> +
>>> +	if (!mcfg_table)
>>> +		return &pci_generic_ecam_ops;
>>> +
>>> +	/*
>>> +	 * Match against platform specific quirks and return
>> corresponding
>>> +	 * CAM ops.
>>> +	 *
>>> +	 * First match against PCI topology <domain:bus> then use OEM ID
>> and
>>> +	 * OEM revision from MCFG table standard header.
>>> +	 */
>>> +	for (f = __start_acpi_mcfg_fixups; f < __end_acpi_mcfg_fixups;
>> f++) {
>>> +		if ((f->domain == domain || f->domain ==
>> PCI_MCFG_DOMAIN_ANY) &&
>>> +		    (f->bus_num == bus_num || f->bus_num ==
>> PCI_MCFG_BUS_ANY) &&
>>> +		    (!strncmp(f->oem_id, mcfg_table->header.oem_id,
>>> +			      ACPI_OEM_ID_SIZE)) &&
>>> +		    (f->oem_revision == mcfg_table->header.oem_revision))
>>
>> Is this more likely to be updated between quirky and fixed platforms
>> than oem_table_id? What do folks think about using oem_table_id instead
>> of, or in addition to, oem_revision?
>
>  From my understanding we need to stick to this mechanism as (otherwise)
> there are platforms out in the field that would need a FW update.
>
> So I don't think that using oem_table_id "instead" is possible; about
> "in addition" I think it is doable, but I do not see the advantage much.
> I mean that if a platform gets fixed the oem revision should change too,
> Right?

I think you are correct.  My take away on discussions about using this 
style of quirk matching was that we would require the oem_revision to 
change as different quirks (or lack of quirks) were required.

David Daney


>
> Thanks
>
> Gab
>