[PATCH v3 30/41] KVM: arm64: Prepare to handle deferred save/restore of 32-bit registers

[Julien Thierry]

Hi,

On 12/01/18 12:07, Christoffer Dall wrote:
> 32-bit registers are not used by a 64-bit host kernel and can be
> deferred, but we need to rework the accesses to this register to access
> the latest value depending on whether or not guest system registers are
> loaded on the CPU or only reside in memory.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>

Reviewed-by: Julien Thierry <julien.thierry at arm.com>

> ---
>   arch/arm64/include/asm/kvm_emulate.h | 32 +++++-------------
>   arch/arm64/kvm/regmap.c              | 65 ++++++++++++++++++++++++++----------
>   arch/arm64/kvm/sys_regs.c            |  6 ++--
>   3 files changed, 60 insertions(+), 43 deletions(-)
> 

[...]

> diff --git a/arch/arm64/kvm/regmap.c b/arch/arm64/kvm/regmap.c
> index bbc6ae32e4af..3f65098aff8d 100644
> --- a/arch/arm64/kvm/regmap.c
> +++ b/arch/arm64/kvm/regmap.c
> @@ -141,28 +141,59 @@ unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num)
>   /*
>    * Return the SPSR for the current mode of the virtual CPU.
>    */
> -unsigned long *vcpu_spsr32(const struct kvm_vcpu *vcpu)
> +static int vcpu_spsr32_mode(const struct kvm_vcpu *vcpu)
>   {
>   	unsigned long mode = *vcpu_cpsr(vcpu) & COMPAT_PSR_MODE_MASK;
>   	switch (mode) {
> -	case COMPAT_PSR_MODE_SVC:
> -		mode = KVM_SPSR_SVC;
> -		break;
> -	case COMPAT_PSR_MODE_ABT:
> -		mode = KVM_SPSR_ABT;
> -		break;
> -	case COMPAT_PSR_MODE_UND:
> -		mode = KVM_SPSR_UND;
> -		break;
> -	case COMPAT_PSR_MODE_IRQ:
> -		mode = KVM_SPSR_IRQ;
> -		break;
> -	case COMPAT_PSR_MODE_FIQ:
> -		mode = KVM_SPSR_FIQ;
> -		break;
> +	case COMPAT_PSR_MODE_SVC: return KVM_SPSR_SVC;
> +	case COMPAT_PSR_MODE_ABT: return KVM_SPSR_ABT;
> +	case COMPAT_PSR_MODE_UND: return KVM_SPSR_UND;
> +	case COMPAT_PSR_MODE_IRQ: return KVM_SPSR_IRQ;
> +	case COMPAT_PSR_MODE_FIQ: return KVM_SPSR_FIQ;
> +	default: BUG();
> +	}
> +}
> +
> +unsigned long vcpu_read_spsr32(const struct kvm_vcpu *vcpu)
> +{
> +	int spsr_idx = vcpu_spsr32_mode(vcpu);
> +
> +	if (!vcpu->arch.sysregs_loaded_on_cpu)
> +		return vcpu_gp_regs(vcpu)->spsr[spsr_idx];
> +
> +	switch (spsr_idx) {
> +	case KVM_SPSR_SVC:
> +		return read_sysreg_el1(spsr);
> +	case KVM_SPSR_ABT:
> +		return read_sysreg(spsr_abt);
> +	case KVM_SPSR_UND:
> +		return read_sysreg(spsr_und);
> +	case KVM_SPSR_IRQ:
> +		return read_sysreg(spsr_irq);
> +	case KVM_SPSR_FIQ:
> +		return read_sysreg(spsr_fiq);
>   	default:
>   		BUG();

Nit:

Since the BUG() is in vcpu_spsr32_mode now, you can probably remove it 
here (or add it to vcpu_write_sprsr32 for consistency).

>   	}
> +}
>   
> -	return (unsigned long *)&vcpu_gp_regs(vcpu)->spsr[mode];
> +void vcpu_write_spsr32(struct kvm_vcpu *vcpu, unsigned long v)
> +{
> +	int spsr_idx = vcpu_spsr32_mode(vcpu);
> +
> +	if (!vcpu->arch.sysregs_loaded_on_cpu)
> +		vcpu_gp_regs(vcpu)->spsr[spsr_idx] = v;
> +
> +	switch (spsr_idx) {
> +	case KVM_SPSR_SVC:
> +		write_sysreg_el1(v, spsr);
> +	case KVM_SPSR_ABT:
> +		write_sysreg(v, spsr_abt);
> +	case KVM_SPSR_UND:
> +		write_sysreg(v, spsr_und);
> +	case KVM_SPSR_IRQ:
> +		write_sysreg(v, spsr_irq);
> +	case KVM_SPSR_FIQ:
> +		write_sysreg(v, spsr_fiq);
> +	}
>   }

Cheers,

-- 
Julien Thierry