Re: [PATCH 10/26] KVM: arm64: Refactor vcpu_{read,write}_sys_reg

James Morse
2020-05-26T16:28:59Z

Hi Marc,

On 22/04/2020 13:00, Marc Zyngier wrote:
> Extract the direct HW accessors for later reuse.

> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 51db934702b64..46f218982df8c 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c

> +u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg)
> +{
> + u64 val = 0x8badf00d8badf00d;
> +
> + if (!vcpu->arch.sysregs_loaded_on_cpu) {
> + goto memory_read;
> }
>
> -immediate_write:
> + if (__vcpu_read_sys_reg_from_cpu(reg, &val))
> + return val;
> +
> +memory_read:
> + return __vcpu_sys_reg(vcpu, reg);
> +}

The goto here is a bit odd, is it just an artefact of how we got here?
Is this easier on the eye?:
| u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg)
| {
| u64 val = 0x8badf00d8badf00d;
|
| if (vcpu->arch.sysregs_loaded_on_cpu &&
| __vcpu_read_sys_reg_from_cpu(reg, &val))
| return val;
|
| return __vcpu_sys_reg(vcpu, reg);
| }

> +void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
> +{
> + if (!vcpu->arch.sysregs_loaded_on_cpu)
> + goto memory_write;
> +
> + if (__vcpu_write_sys_reg_to_cpu(val, reg))
> + return;
> +
> +memory_write:
> __vcpu_sys_reg(vcpu, reg) = val;
> }

Again I think its clearer without the goto....

Regardless:
Reviewed-by: James Morse <james.morse@arm.com>

Thanks,

James