Re: [PATCH 3/5] KVM: arm/arm64: factor out common wfe/wfi emulation code

[Marc Zyngier <marc.zyngier@arm.com>]

On 29/09/17 12:30, Andrew Jones wrote:
> Before we add more common code to the wfi emulation, let's first
> factor out everything common.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  arch/arm/include/asm/kvm_host.h   |  2 ++
>  arch/arm/kvm/handle_exit.c        | 14 +++++---------
>  arch/arm64/include/asm/kvm_host.h |  2 ++
>  arch/arm64/kvm/handle_exit.c      | 14 +++++---------
>  virt/kvm/arm/arm.c                | 13 +++++++++++++
>  virt/kvm/arm/psci.c               | 15 +++++++--------
>  6 files changed, 34 insertions(+), 26 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 85f3c20b9759..964320825372 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -231,6 +231,8 @@ void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu);
>  void kvm_arm_vcpu_power_on(struct kvm_vcpu *vcpu);
>  void kvm_arm_halt_guest(struct kvm *kvm);
>  void kvm_arm_resume_guest(struct kvm *kvm);
> +void kvm_arm_emulate_wfe(struct kvm_vcpu *vcpu);
> +void kvm_arm_emulate_wfi(struct kvm_vcpu *vcpu);
>  
>  int kvm_arm_copy_coproc_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
>  unsigned long kvm_arm_num_coproc_regs(struct kvm_vcpu *vcpu);
> diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
> index cf8bf6bf87c4..e40466577c87 100644
> --- a/arch/arm/kvm/handle_exit.c
> +++ b/arch/arm/kvm/handle_exit.c
> @@ -57,22 +57,18 @@ static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
>   * @run:	the kvm_run structure pointer
>   *
>   * WFE: Yield the CPU and come back to this vcpu when the scheduler
> - * decides to.
> - * WFI: Simply call kvm_vcpu_block(), which will halt execution of
> - * world-switches and schedule other host processes until there is an
> - * incoming IRQ or FIQ to the VM.
> + *      decides to.
> + * WFI: Halt execution of world-switches and schedule other host
> + *      processes until there is an incoming IRQ or FIQ to the VM.
>   */
>  static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  {
>  	if (kvm_vcpu_get_hsr(vcpu) & HSR_WFI_IS_WFE) {
>  		trace_kvm_wfx(*vcpu_pc(vcpu), true);
> -		vcpu->stat.wfe_exit_stat++;
> -		kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
> +		kvm_arm_emulate_wfe(vcpu);
>  	} else {
>  		trace_kvm_wfx(*vcpu_pc(vcpu), false);
> -		vcpu->stat.wfi_exit_stat++;
> -		kvm_vcpu_block(vcpu);
> -		kvm_clear_request(KVM_REQ_UNHALT, vcpu);
> +		kvm_arm_emulate_wfi(vcpu);
>  	}
>  
>  	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 25545a87de11..a774f6b30474 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -332,6 +332,8 @@ void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu);
>  void kvm_arm_vcpu_power_on(struct kvm_vcpu *vcpu);
>  void kvm_arm_halt_guest(struct kvm *kvm);
>  void kvm_arm_resume_guest(struct kvm *kvm);
> +void kvm_arm_emulate_wfe(struct kvm_vcpu *vcpu);
> +void kvm_arm_emulate_wfi(struct kvm_vcpu *vcpu);
>  
>  u64 __kvm_call_hyp(void *hypfn, ...);
>  #define kvm_call_hyp(f, ...) __kvm_call_hyp(kvm_ksym_ref(f), ##__VA_ARGS__)
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 7debb74843a0..7ba50a296d10 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -74,22 +74,18 @@ static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run)
>   * @vcpu:	the vcpu pointer
>   *
>   * WFE: Yield the CPU and come back to this vcpu when the scheduler
> - * decides to.
> - * WFI: Simply call kvm_vcpu_block(), which will halt execution of
> - * world-switches and schedule other host processes until there is an
> - * incoming IRQ or FIQ to the VM.
> + *      decides to.
> + * WFI: Halt execution of world-switches and schedule other host
> + *      processes until there is an incoming IRQ or FIQ to the VM.
>   */
>  static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  {
>  	if (kvm_vcpu_get_hsr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
>  		trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
> -		vcpu->stat.wfe_exit_stat++;
> -		kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
> +		kvm_arm_emulate_wfe(vcpu);
>  	} else {
>  		trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
> -		vcpu->stat.wfi_exit_stat++;
> -		kvm_vcpu_block(vcpu);
> -		kvm_clear_request(KVM_REQ_UNHALT, vcpu);
> +		kvm_arm_emulate_wfi(vcpu);
>  	}
>  
>  	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 954e77608d29..220a3dbda76c 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -573,6 +573,19 @@ void kvm_arm_resume_guest(struct kvm *kvm)
>  	}
>  }
>  
> +void kvm_arm_emulate_wfe(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->stat.wfe_exit_stat++;
> +	kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
> +}
> +
> +void kvm_arm_emulate_wfi(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->stat.wfi_exit_stat++;
> +	kvm_vcpu_block(vcpu);
> +	kvm_clear_request(KVM_REQ_UNHALT, vcpu);
> +}
> +
>  static void vcpu_req_sleep(struct kvm_vcpu *vcpu)
>  {
>  	struct swait_queue_head *wq = kvm_arch_vcpu_wq(vcpu);
> diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
> index a7bf152f1247..755c415304ea 100644
> --- a/virt/kvm/arm/psci.c
> +++ b/virt/kvm/arm/psci.c
> @@ -50,20 +50,19 @@ static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
>  	 * This means for KVM the wakeup events are interrupts and
>  	 * this is consistent with intended use of StateID as described
>  	 * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
> -	 *
> -	 * Further, we also treat power-down request to be same as
> -	 * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
> -	 * specification (ARM DEN 0022A). This means all suspend states
> -	 * for KVM will preserve the register state.
>  	 */
> -	kvm_vcpu_block(vcpu);
> -	kvm_clear_request(KVM_REQ_UNHALT, vcpu);
> -
> +	kvm_arm_emulate_wfi(vcpu);
>  	return PSCI_RET_SUCCESS;
>  }
>  
>  static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
>  {
> +	/*
> +	 * We treat a power-off request the same as a stand-by request,
> +	 * as-per section 5.4.2 clause 3 of PSCI v0.2* specification
> +	 * (ARM DEN 0022A). This means all suspend states for KVM will
> +	 * preserve the register state.
> +	 */
>  	kvm_arm_vcpu_power_off(vcpu);
>  }
>  
> 

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...