Re: [PATCH] x86/PV32: restore PAE-extended-CR3 logic

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Feb 15, 2023 at 03:54:11PM +0100, Jan Beulich wrote:
> While the PAE-extended-CR3 VM assist is a 32-bit only concept, it still
> applies to guests also when run on a 64-bit hypervisor: The "extended
> CR3" format has to be used there as well, to fit the address in the only
> 32-bit wide register there. As a result it was a mistake that the check
> was never enabled for that case, and was then mistakenly deleted in the
> course of removal of 32-bit-Xen code (218adf199e68 ["x86: We can assume
> CONFIG_PAGING_LEVELS==4"]).
> 
> Similarly during Dom0 construction kernel awareness needs to be taken
> into account, and respective code was again mistakenly never enabled for
> 32-bit Dom0 when running on 64-bit Xen (and thus wrongly deleted by
> 5d1181a5ea5e ["xen: Remove x86_32 build target"]).
> 
> At the same time restrict enabling of the assist for Dom0 to just the
> 32-bit case. Furthermore there's no need for an atomic update there.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, Roger.