Re: [PATCH RFCv2 12/15] xen/arm: add Persistent Map (PMAP) infrastructure

[Wei Liu <wl@xxxxxxx>]

On Sun, Apr 25, 2021 at 09:13:15PM +0100, Julien Grall wrote:
> From: Wei Liu <wei.liu2@xxxxxxxxxx>
> 
> The basic idea is like Persistent Kernel Map (PKMAP) in Linux. We
> pre-populate all the relevant page tables before the system is fully
> set up.
> 
> We will need it on Arm in order to rework the arm64 version of
> xenheap_setup_mappings() as we may need to use pages allocated from
> the boot allocator before they are effectively mapped.
> 
> This infrastructure is not lock-protected therefore can only be used
> before smpboot. After smpboot, map_domain_page() has to be used.
> 
> This is based on the x86 version [1] that was originally implemented
> by Wei Liu.
> 
> Take the opportunity to switch the parameter attr from unsigned to
> unsigned int.
> 
> [1] 
> <e92da4ad6015b6089737fcccba3ec1d6424649a5.1588278317.git.hongyxia@xxxxxxxxxx>
> 
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Signed-off-by: Hongyan Xia <hongyxia@xxxxxxxxxx>
> [julien: Adapted for Arm]
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> 
> ---
>     Changes in v2:
>         - New patch
> 
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Cc: Hongian Xia <hongyax@xxxxxxxxxx>
> 
> This is mostly a copy of the PMAP infrastructure currently discussed
> on x86. The only difference is how the page-tables are updated.
> 
> I think we want to consider to provide a common infrastructure. But
> I haven't done it yet to gather feedback on the overall series
> first.

+1. This infrastructure should be common code with arch hooks where
appropriate.

Wei.