Xen project Mailing List

[Xen-devel] Re: Doubt regarding virtual memory mapping from hypervisor to a domain

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

From: Kaustubh Kabra <kaustubhwise@xxxxxxxxx>

Date: Thu, 10 Feb 2011 18:56:52 +0530

Cc: jeremy@xxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, vasani.ashwin@xxxxxxxxx, Tim.Deegan@xxxxxxxxxx, kabrakaustubh@xxxxxxxxx, keir@xxxxxxx

Delivery-date: Thu, 10 Feb 2011 05:28:19 -0800

Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=kbp+fBDbbRfKIfpmQilnoq0p0W3TByEVzfuqrzYRAvkYcB/vuPNXAePY4GnvfOvwvh PWRTgSmBAtUBVbtsaLJRY/QR5fjRXorfRs16NVxlMk1OnpEw+SnXC1FBTSRDZdimojw7 51u5asF4zl39UIcUHfLfuGQrYZyFyaXm1tcd8=

List-id: Xen developer discussion <xen-devel.lists.xensource.com>

On Mon, Jan 31, 2011 at 9:06 PM, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> wrote:

> From: Kaustubh Kabra [mailto:kaustubhwise@xxxxxxxxx]
> I have allocated few order=9 pages in Xen memory space using
> alloc_domheap_pages(NULL,9,0) during boot time just before domain is
> created (dom0 = domain_create(0, DOMCRF_s3_integrity, DOM0_SSIDREF) in
> xen/arch/x86/setup.c).
>
> I got the following virtual addresses in xen log message-
> (XEN) a2k2: Virt_addr:ffff83011cc00000 MFN:11cc00
> (XEN) a2k2: Virt_addr:ffff83011ca00000 MFN:11ca00
> (XEN) a2k2: Virt_addr:ffff83011c800000 MFN:11c800
> (XEN) a2k2: Virt_addr:ffff83011c600000 MFN:11c600
> (XEN) a2k2: Virt_addr:ffff83011c400000 MFN:11c400
> (XEN) a2k2: Virt_addr:ffff83011c200000 MFN:11c200
> (XEN) a2k2: Virt_addr:ffff83011c000000 MFN:11c000
> (XEN) a2k2: Virt_addr:ffff83011be00000 MFN:11be00
>
> As per config.h file Xen memory map,the virtual mapping shows that the
> memory is allocated in
> 1:1 direct mapping of all physical memory .Can anyone elaborate
> regarding this mapping ?

It's not clear what you are asking. Can you be more precise?

> Now can I allocate this mapped memory reserved by Xen hypervisor to
> any domain through any existing or my new hypercall?

Precisely, i want to allocate this mfn to a requesting domain by making a PMD entry. I tried using xen_set_pte and other hugetlb functions but it cannot write as it is in read-only area . So, I passed this new formed PTE formed using this mfn to hypervisor and tried setting the required PMD entry to this new PTE, but xen crashes .

Again, it's not clear what you are asking. If you are
asking if the guest can map the order=9 page into its
memory space, I think the answer is no. If you are
asking if Xen can use the memory on behalf of a
domain, for example to copy data from the domain into
Xen (like tmem does), I think the answer is yes.

Attachment: xen-patch.patch
Description: Text Data

Attachment: jeremy2-6-32-27.patch
Description: Text Data

_______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel