Hello,
Please read http://wiki.xen.org/xenwiki/AskingXenDevelQuestions before
posting again; it's pretty unclear from your email what you're trying to
do and how it fails.
At 17:16 +0800 on 12 Sep (1315847793), ???? wrote:
> Hi,everyone
> I have been using dbg_pv_va2mfn() function to scan PV dom's page
> table.However,when i intended to modify the page table's entry.Something
> went wrong.
> Should I modify the P2M and M2P table,either?But I kind of lose track of how
> things work at P2M and M2P table.Can someone tell me something about these
> tables.
> Or can someone can tell me which function can come in handy,or where to look
> in.
> I am in the middle of a project that needs to manipulate the page table in
> dom.
OK, I guess from the code below that you want to change the contents of
a PV guest's pagetables from inside Xen? That's not really allowed --
since PV guests make their own pagetables you need to have the guest
OS's cooperation.
If you tell us what the project is, and _why_ you want to do this, we
might be able to suggest a better approach.
Cheers,
Tim.
> For example,
> static unsigned long
> dbg_pv_va2mfn(dbgva_t vaddr, struct domain *dp, uint64_t pgd3val)
> {
> l3_pgentry_t l3e, *l3t;
> l2_pgentry_t l2e, *l2t;
> l1_pgentry_t l1e, *l1t;
> unsigned long cr3 = (pgd3val ? pgd3val : dp->vcpu[0]->arch.cr3);
> unsigned long mfn = cr3 >> PAGE_SHIFT;
>
> DBGP2("vaddr:%lx domid:%d cr3:%lx pgd3:%lx\n", vaddr, dp->domain_id,
> cr3, pgd3val);
>
> if ( pgd3val == 0 )
> {
> l3t = map_domain_page(mfn);
> l3t += (cr3 & 0xFE0UL) >> 3;
> l3e = l3t[l3_table_offset(vaddr)];
> mfn = l3e_get_pfn(l3e);
> unmap_domain_page(l3t);
> if ( !(l3e_get_flags(l3e) & _PAGE_PRESENT) )
> return INVALID_MFN;
> }
>
> l2t = map_domain_page(mfn);
> l2e = l2t[l2_table_offset(vaddr)];
> mfn = l2e_get_pfn(l2e);
> unmap_domain_page(l2t);
> if ( !(l2e_get_flags(l2e) & _PAGE_PRESENT) ||
> (l2e_get_flags(l2e) & _PAGE_PSE) )
> return INVALID_MFN;
>
> l1t = map_domain_page(mfn);
> l1e = l1t[l1_table_offset(vaddr)];----------------------------------(1)
> mfn = l1e_get_pfn(l1e);----------------------------------------------(2)
>
> unmap_domain_page(l1t);
>
> return mfn_valid(mfn) ? mfn : INVALID_MFN;
> }
> What should i do if i want to change the l1e page table entry.I allocate a
> page using the function alloc_domheap_page,and use l1e_from_page() to write
> the l1e entry,but it proved to be wrong,and my system keeps reboot itself.
> Can anyone gives me a hand?
>
>
> Thanks
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
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