Re: [PATCH v2] x86/xen: fix init of balloon stats again

[Juergen Gross]

On 05.08.26 11:40, Roger Pau Monne wrote:
> The handling of extra memory regions done in balloon_add_regions() is not
> correct for PV guests, since the initial target is set to reflect the real
> memory the system has, not what's described on the memory map, which can be
> higher if memory != maxmem.
>
> Introduce separate logic for addition vs subtraction in
> balloon_add_regions() and handle extra regions correctly by adding them to
> the total amount of pages, instead of subtracting from the current and
> target pages amounts.
>
> In the common case PV domU/dom0 and PVH dom0 will use the addition path,
> since the initial target reflects the real assigned memory.  HVM and PVH
> domUs use the subtraction path, since the target is set based on the amount
> of memory reported in the memory map, without accounting for released
> regions.
>
> Fixes: 87af633689ce ("x86/xen: fix balloon target initialization for PVH dom0")
> Fixes: 0949c646d646 ("Partial revert "x86/xen: fix balloon target initialization for PVH dom0"")
> Signed-off-by: Roger Pau Monné <roger@xxxxxxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen

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