Re: [Xen-devel] [PATCH] x86: Get rid of p2m_host array allocation for HVM guests

[Jan Beulich <JBeulich@xxxxxxxx>]

On 03.07.2019 15:06, Varad Gautam wrote:
> When allocating the guest memory for an HVM domain, libxc keeps the P2M
> mapping for the entirety of the guest memory around for the time of the
> launch as xc_dom_image->p2m_host. For guests that have a large memory
> (3904 GiB), the p2m_host allocation takes more than 7.5 GiB of space, and
> leaves xl susceptible to getting OOM-killed on guest creation.
> 
> Convert the p2m_host table lookups to an arch-specific function that
> returns the mapping on-the-fly for x86 HVM guests to avoid this
> allocation, bringing down xl's memory usage from > 8GiB to < 70Mib for
> such launches.
> 
> Signed-off-by: Varad Gautam <vrd@xxxxxxxxx>
> 
> ---
> 
> Applies to stable-4.11+.
> 
>   tools/libxc/include/xc_dom.h |  11 +++-
>   tools/libxc/xc_dom_arm.c     |   2 +
>   tools/libxc/xc_dom_core.c    |   4 +-
>   tools/libxc/xc_dom_x86.c     | 126 
> ++++++++++++++++++++++++++++---------------
>   4 files changed, 99 insertions(+), 44 deletions(-)

May I ask that you tag such patches correctly? Seeing the subject, I've
assumed the Cc list isn't right, thus pulling it into my to-be-reviewed
folder. The subject here really wants to contain e.g. libxc, like in
"libxc/x86: ...".

Thanks, Jan
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