linux-kernel - Re: [PATCH] PCI: Clear all bridge res MEM

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Date:	Wed, 10 Dec 2014 22:34:28 +0800
From:	Wei Yang <weiyang@...ux.vnet.ibm.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Gavin Shan <gwshan@...ux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Marek Kordík <kordikmarek@...il.com>,
	Alexey Voronkov <zermond@...il.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: Clear all bridge res MEM_64 if host bridge has non
 mem64

My mutt hang, in case the mail isn't sent out, I resend it.

On Wed, Dec 10, 2014 at 10:15:37PM +0800, Wei Yang wrote:
>On Tue, Dec 09, 2014 at 03:13:49PM -0800, Yinghai Lu wrote:
>>On Tue, Dec 9, 2014 at 1:53 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>>> On Tue, Dec 9, 2014 at 2:34 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>>>> +       list_for_each_entry(window, &bridge->windows, list) {
>>>> +               res = window->res;
>>>> +               if (resource_type(res) == IORESOURCE_MEM ||
>>>> +                   res->end > 0xffffffff) {
>>>> +                       bridge->has_mem64_res = true;
>>>
>>> This is an interesting idea, but I think you're checking CPU addresses
>>> here, and you need to check PCI bus addresses.
>>
>>Looks like those IBM platforms have res > 4g, but pci bus address < 4g.
>>If we check pci bus address, and then we would break those platforms.
>>

Hi, Yinghai

I did some test with patch on my machine. It looks good.

While as Bjorn mentioned, I think we could change it a little. The pci space
on our machine is like this:

        cpu address                               pci address
  MEM   0x00003ff280000000..0x00003ff2fffeffff -> 0x00000000 8000 0000
  MEM64 0x00003d5000000000..0x00003d5fffffffff -> 0x00003d50 0000 0000

Each root bridge has two MMIO window. From this output we could see the pci
address for 64-bit window is above 4G.

I did a little change on your code, like this

        list_for_each_entry(window, &bridge->windows, list) {
                res = window->res;
                if (resource_type(res) == IORESOURCE_MEM ||
-                   res->end > 0xffffffff) {
+                   (res->end - window->offset) > 0xffffffff) {
                        bridge->has_mem64_res = true;
                        break;
                }
        }

This also works on my machine.

One more question, with this patch, do we still need previous patch for
Marek's problem?

>>Yinghai
>
>-- 
>Richard Yang
>Help you, Help me

-- 
Richard Yang
Help you, Help me

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