[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] pagetable RO

Hi, everyone,
      The thing is:  The pages that make up a pagetable must be mapped read-only in the guest. This prevents uncontrolled guest updates to the pagetable. Xen strictly enforces this, and will disallow any pagetable update which will end up mapping pagetable page RW, and will disallow using any writable page as a pagetable.
      Say, the sub-op:
MMU_NORMAL_PT_UPDATE, if the page that ptr of struct mmu_update points to is PGT_l2_page_table, then the address part of val of struct mmu_update points to a page, which is PGT_l1_page_table. However, I couldn't find the protections for this PGT_l1_page_table page in the do_mmu_update, is it already set as read-only before launching MMU_UPDATE hypercall?     
      If someone would like to offer me some help, I really appreciate it.

Best regards,

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.