[PATCH 00/15] Move vcpu_load and vcpu_put calls to arch code

[david@redhat.com (David Hildenbrand)]

On 25.11.2017 21:57, Christoffer Dall wrote:
> Some architectures may decide to do different things during
> kvm_arch_vcpu_load depending on the ioctl being executed.  For example,
> arm64 is about to do significant work in vcpu load/put when running a
> vcpu, but it's problematic to do this for any other vcpu ioctl than
> KVM_RUN.
> 
> Further, while it may be possible to call kvm_arch_vcpu_load() for a
> number of non-KVM_RUN ioctls, it makes the KVM/ARM code more difficult
> to reason about, especially after my optimization series, because a lot
> of things can now happen, where we have to consider if we're really in
> the process of running a vcpu or not.
> 
> This series will first move the vcpu_load() and vcpu_put() calls in the
> arch generic dispatch function into each case of the switch statement
> and then, one-by-one, pushed the calls down into the architecture
> specific code making the changes for each ioctl as required.
> 
> Thanks,
> -Christoffer
> 
> Christoffer Dall (15):
>   KVM: Prepare for moving vcpu_load/vcpu_put into arch specific code
>   KVM: Factor out vcpu->pid adjustment for KVM_RUN
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_run
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_get_regs
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_set_regs
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_get_sregs
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_set_sregs
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_get_mpstate
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_set_mpstate
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_translate
>   KVM: Move vcpu_load to arch-specific
>     kvm_arch_vcpu_ioctl_set_guest_debug
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_get_fpu
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl_set_fpu
>   KVM: Move vcpu_load to arch-specific kvm_arch_vcpu_ioctl
>   KVM: arm/arm64: Avoid vcpu_load for other vcpu ioctls than KVM_RUN
> 
>  arch/arm64/kvm/guest.c     |  17 +++++--
>  arch/mips/kvm/mips.c       |  72 +++++++++++++++++++--------
>  arch/powerpc/kvm/book3s.c  |  38 +++++++++++++-
>  arch/powerpc/kvm/booke.c   |  65 +++++++++++++++++++-----
>  arch/powerpc/kvm/powerpc.c |  24 ++++++---
>  arch/s390/kvm/kvm-s390.c   | 119 +++++++++++++++++++++++++++++++++++++-------
>  arch/x86/kvm/x86.c         | 121 ++++++++++++++++++++++++++++++++++++++-------
>  include/linux/kvm_host.h   |   2 +
>  virt/kvm/arm/arm.c         |  91 +++++++++++++++++++++++++---------
>  virt/kvm/kvm_main.c        |  43 +++++++---------
>  10 files changed, 463 insertions(+), 129 deletions(-)
> 

Looking at the amount of code we duplicate, I wonder if simple ifdefery
(if possible) would be easier for the single known "special" case.

(most probably an unpopular opinion :) )

-- 

Thanks,

David / dhildenb