Re: [PATCH v2 1/9] x86/shadow: replace sh_reset_l3_up_pointers()

[George Dunlap <george.dunlap@xxxxxxxxx>]

On Wed, Jan 11, 2023 at 1:52 PM Jan Beulich <jbeulich@xxxxxxxx> wrote:

Rather than doing a separate hash walk (and then even using the vCPU
variant, which is to go away), do the up-pointer-clearing right in
sh_unpin(), as an alternative to the (now further limited) enlisting on
a "free floating" list fragment. This utilizes the fact that such list
fragments are traversed only for multi-page shadows (in shadow_free()).
Furthermore sh_terminate_list() is a safe guard only anyway, which isn't
in use in the common case (it actually does anything only for BIGMEM
configurations).

One thing that seems strange about this patch is that you're essentially adding a field to the domain shadow struct in lieu of adding another another argument to sh_unpin() (unless the bit is referenced elsewhere in subsequent patches, which I haven't reviewed, in part because about half of them don't apply cleanly to the current tree).

 -George