Re: [PATCH v4 34/40] KVM: arm64: Cleanup __activate_traps and __deactive_traps for VHE and non-VHE

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

On Thu, 15 Feb 2018 21:03:26 +0000,
Christoffer Dall wrote:
> 
> To make the code more readable and to avoid the overhead of a function
> call, let's get rid of a pair of the alternative function selectors and
> explicitly call the VHE and non-VHE functions using the has_vhe() static
> key based selector instead, telling the compiler to try to inline the
> static function if it can.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
>  arch/arm64/kvm/hyp/switch.c | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index 5e94955b89ea..0e54fe2aab1c 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -85,7 +85,7 @@ static void __hyp_text __deactivate_traps_common(void)
>  	write_sysreg(0, pmuserenr_el0);
>  }
>  
> -static void __hyp_text __activate_traps_vhe(struct kvm_vcpu *vcpu)
> +static inline void activate_traps_vhe(struct kvm_vcpu *vcpu)
>  {
>  	u64 val;
>  
> @@ -97,7 +97,7 @@ static void __hyp_text __activate_traps_vhe(struct kvm_vcpu *vcpu)
>  	write_sysreg(kvm_get_hyp_vector(), vbar_el1);
>  }
>  
> -static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)
> +static inline void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)

Having both inline and __hyp_text does not make much sense (the
function will be emitted in the section defined by the caller). I
suggest you drop the inline and let the compiler do its magic.

>  {
>  	u64 val;
>  
> @@ -108,11 +108,7 @@ static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)
>  	write_sysreg(val, cptr_el2);
>  }
>  
> -static hyp_alternate_select(__activate_traps_arch,
> -			    __activate_traps_nvhe, __activate_traps_vhe,
> -			    ARM64_HAS_VIRT_HOST_EXTN);
> -
> -static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
> +static inline void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)

Same here, and in other spots in this file.

>  {
>  	u64 hcr = vcpu->arch.hcr_el2;
>  
> @@ -122,10 +118,13 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
>  		write_sysreg_s(vcpu->arch.vsesr_el2, SYS_VSESR_EL2);
>  
>  	__activate_traps_fpsimd32(vcpu);
> -	__activate_traps_arch()(vcpu);
> +	if (has_vhe())
> +		activate_traps_vhe(vcpu);
> +	else
> +		__activate_traps_nvhe(vcpu);
>  }
>  
> -static void __hyp_text __deactivate_traps_vhe(void)
> +static inline void deactivate_traps_vhe(void)
>  {
>  	extern char vectors[];	/* kernel exception vectors */
>  	write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
> @@ -133,7 +132,7 @@ static void __hyp_text __deactivate_traps_vhe(void)
>  	write_sysreg(vectors, vbar_el1);
>  }
>  
> -static void __hyp_text __deactivate_traps_nvhe(void)
> +static inline void __hyp_text __deactivate_traps_nvhe(void)
>  {
>  	u64 mdcr_el2 = read_sysreg(mdcr_el2);
>  
> @@ -147,11 +146,7 @@ static void __hyp_text __deactivate_traps_nvhe(void)
>  	write_sysreg(CPTR_EL2_DEFAULT, cptr_el2);
>  }
>  
> -static hyp_alternate_select(__deactivate_traps_arch,
> -			    __deactivate_traps_nvhe, __deactivate_traps_vhe,
> -			    ARM64_HAS_VIRT_HOST_EXTN);
> -
> -static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
> +static inline void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
>  {
>  	/*
>  	 * If we pended a virtual abort, preserve it until it gets
> @@ -162,7 +157,10 @@ static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
>  	if (vcpu->arch.hcr_el2 & HCR_VSE)
>  		vcpu->arch.hcr_el2 = read_sysreg(hcr_el2);
>  
> -	__deactivate_traps_arch()();
> +	if (has_vhe())
> +		deactivate_traps_vhe();
> +	else
> +		__deactivate_traps_nvhe();
>  }
>  
>  void activate_traps_vhe_load(struct kvm_vcpu *vcpu)
> -- 
> 2.14.2
> 

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.