linux-kernel - Re: [PATCH v3 00/21] x86/xen: untangle PV and PVHVM guest support code

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Date:   Wed, 15 Mar 2017 10:42:45 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        xen-devel@...ts.xenproject.org
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Andrew Jones <drjones@...hat.com>
Subject: Re: [PATCH v3 00/21] x86/xen: untangle PV and PVHVM guest support
 code

On 14/03/17 18:35, Vitaly Kuznetsov wrote:
> Changes since v2:
> - Rebase to 4.11.0-rc1+
> - XEN_HAVE_PVMMU moved to config XEN_PV [Juergen Gross]
> - .pin_vcpu kept for x86_hyper_xen_hvm to support PVH Dom0 in future
>    [Juergen Gross]
> - 'extern' qualifiers dropped from newly introduced function prototypes
>   in headers [Juergen Gross]
> - A couple of #includes added to address build issues with different
>   configs [kbuild test robot].
> - Juergen reviewed-bys added (hope they stand with the above mentioned
>   changes).

They do.

In case nobody objects I'll take this series for 4.12.


Juergen

> 
> The series can also be pulled from https://github.com/vittyvk/linux.git
>  (xen_pv_hvm_split_v3 branch).
> 
> Some patches are known to produce checkpatch.pl WARNINGS and a couple of
> ERRORs, I fixed a few (mostly in _hvm* code I split) and I refrained from
> fixing the rest to make it easier to review. I think that we may leave PV
> code as it is as sooner or later it will go away.
> 
> Original description:
> 
> I have a long-standing idea to separate PV and PVHVM code in kernel and 
> introduce Kconfig options to make it possible to enable the required
> parts only breaking the current 'all or nothing' approach.
> 
> Motivation:
> - Xen related x86 code in kernel is rather big and it is unclear which
>   parts of it are required for PV, for HVM or for both. With PVH coming
>   into picture is becomes even more tangled. It makes it hard to
>   understand/audit the code.
> 
> - In some case we may want to avoid bloating kernel by supporting Xen
>   guests we don't need. In particular, 90% of the code in arch/x86/xen/ is
>   required to support PV guests and one may require PVHVM support only.
> 
> - PV guests are supposed to go away one day and such code separation would
>   help us to get ready.
> 
> This series adds XEN_PV Kconfig option and makes it possible to build PV-only
> and PVHVM-only kernels. It also makes it possible to disable Dom0 support.
> 
> Some patches are rather big but this is mostly just moving code around, no
> functional changes intended. I smoke tested it with PV-only and PVHVM-only
> builds, booted and did save/restore test. I also tried the newly introduced
> PVHv2 guest, it even worked!
> 
> Vitaly Kuznetsov (21):
>   x86/xen: separate PV and HVM hypervisors
>   x86/xen: globalize have_vcpu_info_placement
>   x86/xen: add CONFIG_XEN_PV to Kconfig
>   x86/xen: split off enlighten_pvh.c
>   x86/xen: split off enlighten_hvm.c
>   x86/xen: split off enlighten_pv.c
>   x86/xen: split xen_smp_intr_init()/xen_smp_intr_free()
>   x86/xen: split xen_smp_prepare_boot_cpu()
>   x86/xen: split xen_cpu_die()
>   x86/xen: split off smp_hvm.c
>   x86/xen: split off smp_pv.c
>   x86/xen: split off mmu_hvm.c
>   x86/xen: split off mmu_pv.c
>   x86/xen: split suspend.c for PV and PVHVM guests
>   x86/xen: put setup.c, pmu.c and apic.c under CONFIG_XEN_PV
>   x86/xen: define startup_xen for XEN PV only
>   x86/xen: create stubs for HVM-only builds in page.h
>   xen/balloon: decorate PV-only parts with #ifdef CONFIG_XEN_PV
>   xen: create xen_create/destroy_contiguous_region() stubs for PVHVM
>     only builds
>   x86/xen: enable PVHVM-only builds
>   x86/xen: rename some PV-only functions in smp_pv.c
> 
>  arch/x86/include/asm/hypervisor.h |    3 +-
>  arch/x86/include/asm/xen/page.h   |   25 +
>  arch/x86/kernel/cpu/hypervisor.c  |    7 +-
>  arch/x86/kernel/process_64.c      |    2 +-
>  arch/x86/xen/Kconfig              |   33 +-
>  arch/x86/xen/Makefile             |   16 +-
>  arch/x86/xen/enlighten.c          | 1925 +------------------------
>  arch/x86/xen/enlighten_hvm.c      |  213 +++
>  arch/x86/xen/enlighten_pv.c       | 1522 ++++++++++++++++++++
>  arch/x86/xen/enlighten_pvh.c      |  115 ++
>  arch/x86/xen/mmu.c                | 2776 +------------------------------------
>  arch/x86/xen/mmu_hvm.c            |   79 ++
>  arch/x86/xen/mmu_pv.c             | 2635 +++++++++++++++++++++++++++++++++++
>  arch/x86/xen/pmu.h                |    5 +
>  arch/x86/xen/smp.c                |  517 +------
>  arch/x86/xen/smp.h                |   16 +
>  arch/x86/xen/smp_hvm.c            |   58 +
>  arch/x86/xen/smp_pv.c             |  500 +++++++
>  arch/x86/xen/suspend.c            |   54 -
>  arch/x86/xen/suspend_hvm.c        |   22 +
>  arch/x86/xen/suspend_pv.c         |   46 +
>  arch/x86/xen/xen-head.S           |    4 +
>  arch/x86/xen/xen-ops.h            |   23 +
>  drivers/xen/balloon.c             |   30 +-
>  include/xen/xen-ops.h             |   14 +
>  25 files changed, 5461 insertions(+), 5179 deletions(-)
>  create mode 100644 arch/x86/xen/enlighten_hvm.c
>  create mode 100644 arch/x86/xen/enlighten_pv.c
>  create mode 100644 arch/x86/xen/enlighten_pvh.c
>  create mode 100644 arch/x86/xen/mmu_hvm.c
>  create mode 100644 arch/x86/xen/mmu_pv.c
>  create mode 100644 arch/x86/xen/smp_hvm.c
>  create mode 100644 arch/x86/xen/smp_pv.c
>  create mode 100644 arch/x86/xen/suspend_hvm.c
>  create mode 100644 arch/x86/xen/suspend_pv.c
>