* Pagetable updates
@ 2004-02-19 17:16 Jacob Gorm Hansen
0 siblings, 0 replies; 6+ messages in thread
From: Jacob Gorm Hansen @ 2004-02-19 17:16 UTC (permalink / raw)
To: Xen list
hi,
I am having a problem with some pagetable-updates that seem to by
sneaking past my checks in XenoLinux. I have #undeffed CONFIG_XENO in
mm/memory.c, and have checking code in place in the functions
MULTICALL_flush_page_update_queue() &
__flush_page_update_queue()
in arch/xeno/mm/hypervisor.c.
Is there anywhere else (like in asm-code somewhere) pte-updates are
passed up to Xen without my knowledge?
thanks,
Jacob
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Pagetable updates
@ 2004-02-19 17:16 Jacob Gorm Hansen
2004-02-19 17:24 ` Keir Fraser
0 siblings, 1 reply; 6+ messages in thread
From: Jacob Gorm Hansen @ 2004-02-19 17:16 UTC (permalink / raw)
To: Xen list
hi,
I am having a problem with some pagetable-updates that seem to by
sneaking past my checks in XenoLinux. I have #undeffed CONFIG_XENO in
mm/memory.c, and have checking code in place in the functions
MULTICALL_flush_page_update_queue() &
__flush_page_update_queue()
in arch/xeno/mm/hypervisor.c.
Is there anywhere else (like in asm-code somewhere) pte-updates are
passed up to Xen without my knowledge?
thanks,
Jacob
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Pagetable updates
2004-02-19 17:16 Jacob Gorm Hansen
@ 2004-02-19 17:24 ` Keir Fraser
2004-02-21 4:13 ` Kip Macy
0 siblings, 1 reply; 6+ messages in thread
From: Keir Fraser @ 2004-02-19 17:24 UTC (permalink / raw)
To: Jacob Gorm Hansen; +Cc: Xen list
> hi,
>
> I am having a problem with some pagetable-updates that seem to by
> sneaking past my checks in XenoLinux. I have #undeffed CONFIG_XENO in
> mm/memory.c, and have checking code in place in the functions
>
> MULTICALL_flush_page_update_queue() &
> __flush_page_update_queue()
>
> in arch/xeno/mm/hypervisor.c.
>
> Is there anywhere else (like in asm-code somewhere) pte-updates are
> passed up to Xen without my knowledge?
I think page-table updates are all made via the interface you
mention. Some things (e.g., LDT updates are sometimes done directly --
for example within the GPF handler).
-- Keir
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Pagetable updates
2004-02-19 17:24 ` Keir Fraser
@ 2004-02-21 4:13 ` Kip Macy
2004-02-21 4:34 ` Kip Macy
0 siblings, 1 reply; 6+ messages in thread
From: Kip Macy @ 2004-02-21 4:13 UTC (permalink / raw)
To: Keir Fraser; +Cc: Xen list
What happens if I install a PDE without setting MMU_EXTENDED_COMMAND and
MMUEXT_PIN_L2_TABLE? I'd like to, for backwards compatibility's sake,
have it show up in my KVA.
-Kip
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Pagetable updates
2004-02-21 4:13 ` Kip Macy
@ 2004-02-21 4:34 ` Kip Macy
2004-02-21 8:26 ` Keir Fraser
0 siblings, 1 reply; 6+ messages in thread
From: Kip Macy @ 2004-02-21 4:34 UTC (permalink / raw)
To: Keir Fraser; +Cc: Xen list
To answer my own question I can do the mapping as a separate operation,
but my question still holds with regards to what pinning the "l2 table"
does.
-Kip
On Fri, 20 Feb 2004, Kip Macy wrote:
>
> What happens if I install a PDE without setting MMU_EXTENDED_COMMAND and
> MMUEXT_PIN_L2_TABLE? I'd like to, for backwards compatibility's sake,
> have it show up in my KVA.
>
>
> -Kip
>
>
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
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> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Pagetable updates
2004-02-21 4:34 ` Kip Macy
@ 2004-02-21 8:26 ` Keir Fraser
0 siblings, 0 replies; 6+ messages in thread
From: Keir Fraser @ 2004-02-21 8:26 UTC (permalink / raw)
To: Kip Macy; +Cc: Xen list
When the refcnt of an L2 table is raised from zero, the whole page
table structure is scanned to check it for safety. If the L2 table did
not explicitly have its refcnt pinned to non-zero then this scanning
would occur every time the table was installed into the hardware MMU.
Pinning is *only* a performance enhancement -- you can get away
without using the mechanism, but it will cost you performance.
-- Keir
> To answer my own question I can do the mapping as a separate operation,
> but my question still holds with regards to what pinning the "l2 table"
> does.
>
> -Kip
>
> On Fri, 20 Feb 2004, Kip Macy wrote:
>
> >
> > What happens if I install a PDE without setting MMU_EXTENDED_COMMAND and
> > MMUEXT_PIN_L2_TABLE? I'd like to, for backwards compatibility's sake,
> > have it show up in my KVA.
> >
> >
> > -Kip
> >
> >
> > -------------------------------------------------------
> > SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> > Build and deploy apps & Web services for Linux with
> > a free DVD software kit from IBM. Click Now!
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> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/xen-devel
> >
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2004-02-21 8:26 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-02-19 17:16 Pagetable updates Jacob Gorm Hansen
-- strict thread matches above, loose matches on Subject: below --
2004-02-19 17:16 Jacob Gorm Hansen
2004-02-19 17:24 ` Keir Fraser
2004-02-21 4:13 ` Kip Macy
2004-02-21 4:34 ` Kip Macy
2004-02-21 8:26 ` Keir Fraser
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