Re: [PATCH] xen/x86: fix initial memory balloon target

["Jürgen Groß" <jgross@suse.com>]

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On 14.05.25 10:04, Roger Pau Monne wrote:
> When adding extra memory regions as ballooned pages also adjust the balloon
> target, otherwise when the balloon driver is started it will populate
> memory to match the target value and consume all the extra memory regions
> added.
> 
> This made the usage of the Xen `dom0_mem=,max:` command line parameter for
> dom0 not work as expected, as the target won't be adjusted and when the
> balloon is started it will populate memory straight to the 'max:' value.
> It would equally affect domUs that have memory != maxmem.
> 
> Kernels built with CONFIG_XEN_UNPOPULATED_ALLOC are not affected, because
> the extra memory regions are consumed by the unpopulated allocation driver,
> and then balloon_add_regions() becomes a no-op.
> 
> Reported-by: John <jw@nuclearfallout.net>
> Fixes: 87af633689ce ('x86/xen: fix balloon target initialization for PVH dom0')
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

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