Change 5c371b31be3203 in stable breaks Xen

Change 5c371b31be3203 in stable breaks Xen

[Jeremy Fitzhardinge]

I have a report of Xen breaking between 2.6.27.5 and .6.  I bisected it 
down to change:

commit 5c371b31be32033b0a4a993431484da8a2305369
Author: Yinghai Lu <yhlu.kernel@gmail.com>
Date:   Mon Sep 22 02:52:26 2008 -0700

    x86: fix CONFIG_X86_RESERVE_LOW_64K=y
   
    commit 2216d199b1430d1c0affb1498a9ebdbd9c0de439 upstream
   
    The bad_bios_dmi_table() quirk never triggered because we do DMI setup
    too late. Move it a bit earlier.
   
    Also change the CONFIG_X86_RESERVE_LOW_64K quirk to operate on the e820
    table directly instead of messing with early reservations - this handles
    overlaps (which do occur in this low range of RAM) more gracefully.
   
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

I haven't completely root-caused why this is OK in mainline but failing 
in stable, but this patch works around the problem.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 455575b..abed1dd 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -7,6 +7,7 @@
 #include <linux/bootmem.h>
 #include <linux/slab.h>
 #include <asm/dmi.h>
+#include <asm/xen/hypervisor.h>
 
 /*
  * DMI stands for "Desktop Management Interface".  It is part
@@ -364,6 +365,11 @@ void __init dmi_scan_machine(void)
        char __iomem *p, *q;
        int rc;
 
+#ifdef CONFIG_XEN
+       if (is_running_on_xen())
+               return;
+#endif
+
        if (efi_enabled) {
                if (efi.smbios == EFI_INVALID_TABLE_ADDR)
                        goto out;

Re: Change 5c371b31be3203 in stable breaks Xen

[Ian Campbell]

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On Tue, 2008-11-25 at 13:26 -0800, Jeremy Fitzhardinge wrote:
> I have a report of Xen breaking between 2.6.27.5 and .6.  I bisected
> it 
> down to change:
> 
> commit 5c371b31be32033b0a4a993431484da8a2305369
> Author: Yinghai Lu <yhlu.kernel@gmail.com>
> Date:   Mon Sep 22 02:52:26 2008 -0700
> 
>     x86: fix CONFIG_X86_RESERVE_LOW_64K=y
>    
>     commit 2216d199b1430d1c0affb1498a9ebdbd9c0de439 upstream

Looks like 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7 might be needed in
stable too?
        
        commit 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7
        Author: Ian Campbell <Ian.Campbell@citrix.com>
        Date:   Fri Oct 10 11:27:38 2008 +0100
        
            xen: do not reserve 2 pages of padding between hypervisor and fixmap.
            
            When reserving space for the hypervisor the Xen paravirt backend adds
            an extra two pages (this was carried forward from the 2.6.18-xen tree
            which had them "for safety"). Depending on various CONFIG options this
            can cause the boot time fixmaps to span multiple PMDs which is not
            supported and triggers a WARN in early_ioremap_init().
            
            This was exposed by 2216d199b1430d1c0affb1498a9ebdbd9c0de439 which
            moved the dmi table parsing earlier.
                x86: fix CONFIG_X86_RESERVE_LOW_64K=y
            
                The bad_bios_dmi_table() quirk never triggered because we do DMI setup
                too late. Move it a bit earlier.
            
            There is no real reason to reserve these two extra pages and the
            fixmap already incorporates FIX_HOLE which serves the same
            purpose. None of the other callers of reserve_top_address do this.


-- 
Ian Campbell

Moonchild without an opinion? Satan is skating to work tomorrow!
		-- Brett Manz

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Re: Change 5c371b31be3203 in stable breaks Xen

[Jeremy Fitzhardinge]

Ian Campbell wrote:
> On Tue, 2008-11-25 at 13:26 -0800, Jeremy Fitzhardinge wrote:
>   
>> I have a report of Xen breaking between 2.6.27.5 and .6.  I bisected
>> it 
>> down to change:
>>
>> commit 5c371b31be32033b0a4a993431484da8a2305369
>> Author: Yinghai Lu <yhlu.kernel@gmail.com>
>> Date:   Mon Sep 22 02:52:26 2008 -0700
>>
>>     x86: fix CONFIG_X86_RESERVE_LOW_64K=y
>>    
>>     commit 2216d199b1430d1c0affb1498a9ebdbd9c0de439 upstream
>>     
>
> Looks like 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7 might be needed in
> stable too?
>   

Ah, yes, that looks like the right fix.  I'll see if it helps.

    J

>         
>         commit 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7
>         Author: Ian Campbell <Ian.Campbell@citrix.com>
>         Date:   Fri Oct 10 11:27:38 2008 +0100
>         
>             xen: do not reserve 2 pages of padding between hypervisor and fixmap.
>             
>             When reserving space for the hypervisor the Xen paravirt backend adds
>             an extra two pages (this was carried forward from the 2.6.18-xen tree
>             which had them "for safety"). Depending on various CONFIG options this
>             can cause the boot time fixmaps to span multiple PMDs which is not
>             supported and triggers a WARN in early_ioremap_init().
>             
>             This was exposed by 2216d199b1430d1c0affb1498a9ebdbd9c0de439 which
>             moved the dmi table parsing earlier.
>                 x86: fix CONFIG_X86_RESERVE_LOW_64K=y
>             
>                 The bad_bios_dmi_table() quirk never triggered because we do DMI setup
>                 too late. Move it a bit earlier.
>             
>             There is no real reason to reserve these two extra pages and the
>             fixmap already incorporates FIX_HOLE which serves the same
>             purpose. None of the other callers of reserve_top_address do this.
>
>
>   

Re: [stable] Change 5c371b31be3203 in stable breaks Xen

[Greg KH]

On Tue, Nov 25, 2008 at 03:25:50PM -0800, Jeremy Fitzhardinge wrote:
> Ian Campbell wrote:
> > On Tue, 2008-11-25 at 13:26 -0800, Jeremy Fitzhardinge wrote:
> >   
> >> I have a report of Xen breaking between 2.6.27.5 and .6.  I bisected
> >> it 
> >> down to change:
> >>
> >> commit 5c371b31be32033b0a4a993431484da8a2305369
> >> Author: Yinghai Lu <yhlu.kernel@gmail.com>
> >> Date:   Mon Sep 22 02:52:26 2008 -0700
> >>
> >>     x86: fix CONFIG_X86_RESERVE_LOW_64K=y
> >>    
> >>     commit 2216d199b1430d1c0affb1498a9ebdbd9c0de439 upstream
> >>     
> >
> > Looks like 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7 might be needed in
> > stable too?
> >   
> 
> Ah, yes, that looks like the right fix.  I'll see if it helps.

If so, let us know and we will add it to the next -stable release.

thanks,

greg k-h

Re: [stable] Change 5c371b31be3203 in stable breaks Xen

[Jeremy Fitzhardinge]

Greg KH wrote:
>> Ah, yes, that looks like the right fix.  I'll see if it helps.
>>     
>
> If so, let us know and we will add it to the next -stable release.

Yep.  Cherry-picking 5dc64a3442b98eaa0e3730c35fcf00cf962a93e7 onto 
2.6.27.7 fixes the bug.

Thanks,
    J