[PATCH v4 01/40] KVM: arm/arm64: Avoid vcpu_load for other vcpu ioctls than KVM_RUN

[Andrew Jones]

On Thu, Feb 15, 2018 at 10:02:53PM +0100, Christoffer Dall wrote:
> Calling vcpu_load() registers preempt notifiers for this vcpu and calls
> kvm_arch_vcpu_load().  The latter will soon be doing a lot of heavy
> lifting on arm/arm64 and will try to do things such as enabling the
> virtual timer and setting us up to handle interrupts from the timer
> hardware.
> 
> Loading state onto hardware registers and enabling hardware to signal
> interrupts can be problematic when we're not actually about to run the
> VCPU, because it makes it difficult to establish the right context when
> handling interrupts from the timer, and it makes the register access
> code difficult to reason about.
> 
> Luckily, now when we call vcpu_load in each ioctl implementation, we can
> simply remove the call from the non-KVM_RUN vcpu ioctls, and our
> kvm_arch_vcpu_load() is only used for loading vcpu content to the
> physical CPU when we're actually going to run the vcpu.
> 
> Reviewed-by: Julien Grall <julien.grall at arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> ---
>  arch/arm64/kvm/guest.c | 3 ---
>  virt/kvm/arm/arm.c     | 9 ---------
>  2 files changed, 12 deletions(-)
>

Reviewed-by: Andrew Jones <drjones at redhat.com>