On Tue, Mar 16, 2021 at 10:13:07AM +0000, Marc Zyngier wrote:
> In order to keep the code readable, move the host-save/guest-restore
> sequences in their own functions, with the following changes:
> - the hypervisor ZCR is now set from C code
> - ZCR_EL2 is always used as the EL2 accessor
> 
> This results in some minor assembler macro rework.
> No functional change intended.
> 
> Signed-off-by: Marc Zyngier <[email protected]>
> ---
>  arch/arm64/include/asm/fpsimdmacros.h   |  8 +++--
>  arch/arm64/include/asm/kvm_hyp.h        |  2 +-
>  arch/arm64/kvm/hyp/fpsimd.S             |  2 +-
>  arch/arm64/kvm/hyp/include/hyp/switch.h | 41 +++++++++++++++----------
>  4 files changed, 33 insertions(+), 20 deletions(-)

[...]

> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h 
> b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index fb68271c1a0f..d34dc220a1ce 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -196,6 +196,25 @@ static inline bool __populate_fault_info(struct kvm_vcpu 
> *vcpu)
>       return true;
>  }
>  
> +static inline void __hyp_sve_save_host(struct kvm_vcpu *vcpu)
> +{
> +     struct thread_struct *thread;
> +
> +     thread = container_of(vcpu->arch.host_fpsimd_state, struct 
> thread_struct,
> +                           uw.fpsimd_state);
> +
> +     __sve_save_state(sve_pffr(thread), &vcpu->arch.host_fpsimd_state->fpsr);
> +}
> +
> +static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
> +{
> +     if (read_sysreg_s(SYS_ZCR_EL2) != (vcpu_sve_vq(vcpu) - 1))

Strictly speaking, we should probably be extracting the LEN field from
ZCR_EL2, otherwise this has the potential to go horribly wrong if any of
the RES0 bits are allocated in future.

Other than that:

Acked-by: Will Deacon <[email protected]>

Will
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