[PATCHv5 10/16] x86/tdx: Convert shared memory back to private on kexec

[Edgecombe, Rick P]

The break apart looks good.

On Sat, 2023-12-23 at 02:52 +0300, Kirill A. Shutemov wrote:
> +       while (addr < end) {
> +               unsigned long size;
> +               unsigned int level;
> +               pte_t *pte;
> +
> +               pte = lookup_address(addr, &level);
> +               size = page_level_size(level);
> +
> +               if (pte && pte_decrypted(*pte)) {
> +                       int pages = size / PAGE_SIZE;
> +
> +                       /*
> +                        * Touching memory with shared bit set
> triggers implicit
> +                        * conversion to shared.
> +                        *
> +                        * Make sure nobody touches the shared range
> from
> +                        * now on.
> +                        */
> +                       set_pte(pte, __pte(0));

Does this need a full shootdown at this point, at least in the crash
case? A local flush for the non-crash case might be nice too.

Also, probably a barrier() between set_pte() and
tdx_enc_status_changed().

> +
> +                       if (!tdx_enc_status_changed(addr, pages,
> true)) {
> +                               pr_err("Failed to unshare range %#lx-
> %#lx\n",
> +                                      addr, addr + size);
> +                       }