[PATCHv10 0/9] Xen: extend kexec hypercall for use with pv-ops kernels

[David Vrabel]

The series (for Xen 4.4) improves the kexec hypercall by making Xen
responsible for loading and relocating the image.  This allows kexec
to be usable by pv-ops kernels and should allow kexec to be usable
from a HVM or PVH privileged domain.

I have now tested this with a Linux kernel image using the VGA console
which was what was causing problems in v9 (this turned out to be a
kexec-tools bug).

The required patch series for kexec-tools will be posted shortly and
are available from the xen-v7 branch of:

http://xenbits.xen.org/gitweb/?p=people/dvrabel/kexec-tools.git;a=summary

Changes in v10:

- Document host state on exec.
- Fix kimage_alloc() error path (double free, crash on zero kimage->head).
- Check for segment before expanding it in load_v1.
- Move kexec_lock define into kexec_swap_images().

Changes in v9:

- Update comments to correctly say 4.4.
- Minor updates the kexec_reloc assembly to improve maintainability a
  bit.

Changes in v8:

- Use #defines for compat ABI structures.
- Tweak link time check for kexec_reloc.

Changes in v7:

- No longer use GUEST_HANDLE_64(), get a uniform ABI by using unions
  and explicit padding.
- Only map the segments and not all of RAM.
- Add a mechanism to create mappings for use by the exec'd image (a
  segment with a NULL buf handle).
- Fix a bug where a crash image's code page would by placed at machine
  address 0 (instead of inside the crash region).

Changes in v6:

- Fix double free in KEXEC_load_v1 failure path.
- Only copy the relocation code and not the whole page.
- Add myself as the kexec maintainer.

Changes in v5 (not posted to the list):

- _rsvd -> _pad in one of the public ABI structures.
- Fix bug where trailing pages were not zeroed. This fixes loading a
  64-bit Linux kernel using a more recent version of kexec-tools.
- Check the relocation code fits into a page at link time.

Changes in v4:

- Use paddr_t and page_to_maddr() etc. for portability.
- Add explicit padding to hypercall structures where required.
- Minor cleanup of the kexec_reloc assembly.
- Print a message before exec'ing a crash image.
- Style fixes (tabs, trailing whitespace) and typos.
- Fix a bug where using the V1 interface and unloading a image may crash.

Changes in v3:

- Provide old struct xen_kexec_load if __XEN_INTERFACE_VERSION__ < 4.3
- Adjust new struct xen_kexec_load to avoid unnecessary padding.
- Use domheap pages for the image and control pages.
- Remove the DBG() macros from the reloc code.

David