Re: [PATCH v5 31/69] KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting

[Ganapatrao Kulkarni <gankulkarni@xxxxxxxxxxxxxxxxxxxxxx>]

On 30-11-2021 01:31 am, Marc Zyngier wrote:
> From: Jintack Lim <jintack@xxxxxxxxxxxxxxx>
>
> Forward ELR_EL1, SPSR_EL1 and VBAR_EL1 traps to the virtual EL2 if the
> virtual HCR_EL2.NV bit is set.
>
> This is for recursive nested virtualization.
>
> Signed-off-by: Jintack Lim <jintack@xxxxxxxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
>   arch/arm64/include/asm/kvm_arm.h |  1 +
>   arch/arm64/kvm/sys_regs.c        | 28 +++++++++++++++++++++++++++-
>   2 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> index 9759bc893a51..68af5509e4b0 100644
> --- a/arch/arm64/include/asm/kvm_arm.h
> +++ b/arch/arm64/include/asm/kvm_arm.h
> @@ -20,6 +20,7 @@
>   #define HCR_AMVOFFEN	(UL(1) << 51)
>   #define HCR_FIEN	(UL(1) << 47)
>   #define HCR_FWB		(UL(1) << 46)
> +#define HCR_NV1		(UL(1) << 43)
>   #define HCR_NV		(UL(1) << 42)
>   #define HCR_API		(UL(1) << 41)
>   #define HCR_APK		(UL(1) << 40)
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index e96877fc3b2a..511e06b6f603 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -288,6 +288,22 @@ static bool access_rw(struct kvm_vcpu *vcpu,
>   	return true;
>   }
>   
> +/* This function is to support the recursive nested virtualization */
> +static bool forward_nv1_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
> +{
> +	return forward_traps(vcpu, HCR_NV1);
> +}
> +

Shall we move this helper to emulate-nested.c?

> +static bool access_vbar_el1(struct kvm_vcpu *vcpu,
> +			    struct sys_reg_params *p,
> +			    const struct sys_reg_desc *r)
> +{
> +	if (forward_nv1_traps(vcpu, p))
> +		return false;
> +
> +	return access_rw(vcpu, p, r);
> +}
> +
>   static bool access_sctlr_el2(struct kvm_vcpu *vcpu,
>   			     struct sys_reg_params *p,
>   			     const struct sys_reg_desc *r)
> @@ -1682,6 +1698,7 @@ static bool access_sp_el1(struct kvm_vcpu *vcpu,
>   	return true;
>   }
>   
> +
>   static bool access_elr(struct kvm_vcpu *vcpu,
>   		       struct sys_reg_params *p,
>   		       const struct sys_reg_desc *r)
> @@ -1689,6 +1706,9 @@ static bool access_elr(struct kvm_vcpu *vcpu,
>   	if (el12_reg(p) && forward_nv_traps(vcpu))
>   		return false;
>   
> +	if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
> +		return false;
> +
>   	if (p->is_write)
>   		vcpu_write_sys_reg(vcpu, p->regval, ELR_EL1);
>   	else
> @@ -1704,6 +1724,9 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
>   	if (el12_reg(p) && forward_nv_traps(vcpu))
>   		return false;
>   
> +	if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
> +		return false;
> +
>   	if (p->is_write)
>   		__vcpu_sys_reg(vcpu, SPSR_EL1) = p->regval;
>   	else
> @@ -1719,6 +1742,9 @@ static bool access_spsr_el2(struct kvm_vcpu *vcpu,
>   	if (el12_reg(p) && forward_nv_traps(vcpu))
>   		return false;
>   
> +	if (!el12_reg(p) && forward_nv1_traps(vcpu, p))
> +		return false;
> +
>   	if (p->is_write)
>   		vcpu_write_sys_reg(vcpu, p->regval, SPSR_EL2);
>   	else
> @@ -1927,7 +1953,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>   	{ SYS_DESC(SYS_LORC_EL1), trap_loregion },
>   	{ SYS_DESC(SYS_LORID_EL1), trap_loregion },
>   
> -	{ SYS_DESC(SYS_VBAR_EL1), access_rw, reset_val, VBAR_EL1, 0 },
> +	{ SYS_DESC(SYS_VBAR_EL1), access_vbar_el1, reset_val, VBAR_EL1, 0 },
>   	{ SYS_DESC(SYS_DISR_EL1), NULL, reset_val, DISR_EL1, 0 },
>   
>   	{ SYS_DESC(SYS_ICC_IAR0_EL1), write_to_read_only },

Thanks,
Ganapat