Re: [Xen-devel] Pinning a DomU Guest data page from Hypervisor

[veerasena reddy <veeruyours@xxxxxxxxx>]

Hi,

Thanks for the response.

By pinning, I mean to keep the data page always in main memory for the device to access. Once the device processes the page, i can unpin.
Please correct me, if i understood page pinning concept wrongly.

But, my goal is to keep the page in main memory until the device processes it.

Please advice.

Thanks & Regards,

VSR.

On Wed, Aug 3, 2011 at 10:46 PM, Tim Deegan <tim@xxxxxxx> wrote:

Hi,

At 19:26 +0530 on 03 Aug (1312399607), veerasena reddy wrote:
> I looked into code "xen/arch/x86/mm.c", do_mmuext_op() which was
> invoking xsm_memory_pin_page() only for L1 to L4 page table type pages. Can
> i use the same API to pin data pages?
>
> Could anybody please advice how can I pin a Guest data page from hypervisor.
> Any APIs or sequence of operations to be done on MFN of the guest page?

What exactly do you mean by "pin"?  If you mean stop the guest OS from
paging out the contents, that can't be done from inside the hypervisor.
If you mean keep it from being used as a pagetable, LDT or other special
page, that can be done with get_page_and_type(), but you still need the
guest OS to cooperate.

Tim.

--
Tim Deegan <tim@xxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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