Re: [PATCH v2 0/2] xen/x86: alternative fix for XSA-369

[Boris Ostrovsky]

On 3/24/21 8:24 AM, Roger Pau Monne wrote:
> Hello,
>
> This is a proposal for an alternative fix for XSA-369 that instead of
> special casing XEN_UNPOPULATED_ALLOC to size the p2m relies on making
> XEN_BALLOON_MEMORY_HOTPLUG_LIMIT depend on the generic MEMORY_HOTPLUG
> option rather than XEN_BALLOON_MEMORY_HOTPLUG.
>
> I think this is safer, as we don't want to be special casing any option
> that pulls in generic MEMORY_HOTPLUG without XEN_BALLOON_MEMORY_HOTPLUG.
> Without this we would also need to at least special case ZONE_DEVICE
> which also relies on MEMORY_HOTPLUG, and is what pulls the generic
> MEMORY_HOTPLUG option even when XEN_BALLOON_MEMORY_HOTPLUG is disabled
> with XEN_UNPOPULATED_ALLOC.
>
> Thanks, Roger.
>
> Roger Pau Monne (2):
>   xen/x86: make XEN_BALLOON_MEMORY_HOTPLUG_LIMIT depend on
>     MEMORY_HOTPLUG
>   Revert "xen: fix p2m size in dom0 for disabled memory hotplug case"
>
>  arch/x86/include/asm/xen/page.h | 12 ------------
>  arch/x86/xen/p2m.c              |  7 ++-----
>  arch/x86/xen/setup.c            | 16 ++++++++++++++--
>  drivers/xen/Kconfig             |  4 ++--
>  4 files changed, 18 insertions(+), 21 deletions(-)


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>