Re: [RFC PATCH 0/3] x86/paravirt: Get rid of paravirt patching

[Juergen Gross <jgross@xxxxxxxx>]

Any comments?

On 08.06.23 16:03, Juergen Gross wrote:
> This is a small series getting rid of paravirt patching by switching
> completely to alternative patching for the same functionality.
>
> The basic idea is to add the capability to switch from indirect to
> direct calls via a special alternative patching option.
>
> This removes _some_ of the paravirt macro maze, but most of it needs
> to stay due to the need of hiding the call instructions from the
> compiler in order to avoid needless register save/restore.
>
> What is going away is the nasty stacking of alternative and paravirt
> patching and (of course) the special .parainstructions linker section.
>
> I have tested the series on bare metal and as Xen PV domain to still
> work.
>
> RFC because I'm quite sure there will be some objtool work needed
> (at least removing the specific paravirt handling).
>
> Juergen Gross (3):
>    x86/paravirt: move some functions and defines to alternative
>    x86/alternative: add indirect call patching
>    x86/paravirt: switch mixed paravirt/alternative calls to alternative_2
>
>   arch/x86/include/asm/alternative.h        | 26 +++++-
>   arch/x86/include/asm/paravirt.h           | 39 ++-------
>   arch/x86/include/asm/paravirt_types.h     | 68 +++-------------
>   arch/x86/include/asm/qspinlock_paravirt.h |  4 +-
>   arch/x86/include/asm/text-patching.h      | 12 ---
>   arch/x86/kernel/alternative.c             | 99 +++++++++++------------
>   arch/x86/kernel/callthunks.c              | 17 ++--
>   arch/x86/kernel/kvm.c                     |  4 +-
>   arch/x86/kernel/module.c                  | 20 ++---
>   arch/x86/kernel/paravirt.c                | 54 ++-----------
>   arch/x86/kernel/vmlinux.lds.S             | 13 ---
>   arch/x86/tools/relocs.c                   |  2 +-
>   arch/x86/xen/irq.c                        |  2 +-
>   13 files changed, 111 insertions(+), 249 deletions(-)

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature