Re: [PATCH v4 0/9] libxc: support building large pv-domains

[Juergen Gross <jgross@suse.com>]

On 05/11/15 15:36, Juergen Gross wrote:
> The Xen hypervisor supports starting a dom0 with large memory (up to
> the TB range) by not including the initrd and p2m list in the initial
> kernel mapping. Especially the p2m list can grow larger than the
> available virtual space in the initial mapping.
> 
> The started kernel is indicating the support of each feature via
> elf notes.
> 
> This series enables the domain builder in libxc to do the same as the
> hypervisor. This enables starting of huge pv-domUs via xl.
> 
> Unmapped initrd is supported for 64 and 32 bit domains, omitting the
> p2m from initial kernel mapping is possible for 64 bit domains only.
> 
> Tested with:
> - 32 bit domU (kernel not supporting unmapped initrd)
> - 32 bit domU (kernel supporting unmapped initrd)
> - 1 GB 64 bit domU (kernel supporting unmapped initrd, not p2m)
> - 1 GB 64 bit domU (kernel supporting unmapped initrd and p2m)
> - 900GB 64 bit domU (kernel supporting unmapped initrd and p2m)
> - HVM domU
> 
> Changes in v4:
> - updated patch 1 as suggested by Wei Liu (comment and variable name)
> - modify comment in patch 6 as suggested by Wei Liu
> - rework of patch 8 reducing line count by nearly 100
> - added some additional plausibility checks to patch 8 as suggested by
>   Wei Liu
> - renamed round_pg() to round_pg_up() in patch 9 as suggested by Wei Liu
> 
> Changes in v3:
> - Rebased the complete series to new staging (hvm builder patches by
>   Roger Pau Monne)
> - Removed old patch 1 as it broke stubdom build
> - Introduced new Patch 1 to make allocation of guest memory more clear
>   regarding virtual/physical memory allocation (requested by Ian Campbell)
> - Change name of flag to indicate support of unmapped initrd in patch 2
>   (requested by Ian Campbell)
> - Introduce new patches 3, 4, 5 ("rename domain builder count_pgtables to
>   alloc_pgtables", "introduce domain builder architecture specific data",
>   "use domain builder architecture private data for x86 pv domains") to
>   assist later page table work
> - don't fiddle with initrd virtual address in patch 6 (was patch 3 in v2),
>   add explicit initrd parameters for start_info in struct xc_dom_image
>   instead (requested by Ian Campbell)
> - Introduce new patch 8 ("rework of domain builder's page table handler")
>   to be able to use common helpers for unmapped p2m list (requested by
>   Ian Campbell)
> - use now known segment size in pages for p2m list in patch 9 (was patch
>   5 in v2) instead of fiddling with segment end address (requested by
>   Ian Campbell)
> - split alloc_p2m_list() in patch 9 (was patch 5 in v2) to 32/64 bit
>   variants (requested by Ian Campbell)
> 
> Changes in v2:
> - patch 2 has been removed as it has been applied already
> - introduced new patch 2 as suggested by Ian Campbell: add a flag
>   indicating support of an unmapped initrd to the parsed elf data of
>   the elf_dom_parms structure
> - updated patch description of patch 3 as requested by Ian Campbell
> 
> 
> Juergen Gross (9):
>   libxc: reorganize domain builder guest memory allocator
>   xen: add generic flag to elf_dom_parms indicating support of unmapped
>     initrd
>   libxc: rename domain builder count_pgtables to alloc_pgtables
>   libxc: introduce domain builder architecture specific data
>   libxc: use domain builder architecture private data for x86 pv domains
>   libxc: create unmapped initrd in domain builder if supported
>   libxc: split p2m allocation in domain builder from other magic pages
>   libxc: rework of domain builder's page table handler
>   libxc: create p2m list outside of kernel mapping if supported
> 
>  stubdom/grub/kexec.c               |  12 +-
>  tools/libxc/include/xc_dom.h       |  34 +--
>  tools/libxc/xc_dom_arm.c           |   6 +-
>  tools/libxc/xc_dom_core.c          | 180 ++++++++----
>  tools/libxc/xc_dom_x86.c           | 563 +++++++++++++++++++++----------------
>  tools/libxc/xg_private.h           |  39 +--
>  xen/arch/x86/domain_build.c        |   4 +-
>  xen/common/libelf/libelf-dominfo.c |   3 +
>  xen/include/xen/libelf.h           |   1 +
>  9 files changed, 490 insertions(+), 352 deletions(-)

Could someone please comment on patches 1, 8 and 9?


Juergen