rusty@xxxxxxxxxxxxxxx wrote:
> +/* We walk down the guest page tables to get a guest-physical address */
> +unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
> +{
> + pgd_t gpgd;
> + pte_t gpte;
> +
> + /* First step: get the top-level Guest page table entry. */
> + gpgd = __pgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
> + /* Toplevel not present? We can't map it in. */
> + if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
> + kill_guest(lg, "Bad address %#lx", vaddr);
> +
> + gpte = __pte(lgread_u32(lg, gpte_addr(lg, gpgd, vaddr)));
> + if (!(pte_flags(gpte) & _PAGE_PRESENT))
> + kill_guest(lg, "Bad address %#lx", vaddr);
> +
> + return pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
> +}
That's nice and general, but is it necessary? Is this just to handle
the two cases of booting with P=V, then switching to the normal kernel
offset?
J
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