[PATCH v5 19/26] KVM: arm64: Enumerate SVE register indices for KVM_GET_REG_LIST

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On 18/02/2019 19:52, Dave Martin wrote:
> This patch includes the SVE register IDs in the list returned by
> KVM_GET_REG_LIST, as appropriate.
> 
> On a non-SVE-enabled vcpu, no new IDs are added.
> 
> On an SVE-enabled vcpu, IDs for the FPSIMD V-registers are removed
> from the list, since userspace is required to access the Z-
> registers instead to access their context.  For the variably-sized
> SVE registers, the appropriate set of slice IDs are enumerated,
> depending on the maximum vector length for the vcpu.
> 
> Signed-off-by: Dave Martin <Dave.Martin at arm.com>

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

> 
> ---
> 
> Changes since v4:
> 
>  * Drop KVM_SVE_SLICES(), which is no longer used due to the dropping of
>    register multi-slice support from the series.
> 
>  * Drop register multi-slice support.
> ---
>  arch/arm64/kvm/guest.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 8cfa889..4a2ad60 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -366,6 +366,14 @@ static int copy_core_reg_indices(const struct kvm_vcpu *vcpu,
>  			continue;
>  		}
>  
> +		/*
> +		 * The KVM_REG_ARM64_SVE regs must be used instead of
> +		 * KVM_REG_ARM_CORE for accessing the FPSIMD V-registers on
> +		 * SVE-enabled vcpus:
> +		 */
> +		if (vcpu_has_sve(vcpu) && core_reg_offset_is_vreg(i))
> +			continue;
> +
>  		if (uind) {
>  			if (put_user(reg, *uind))
>  				return -EFAULT;
> @@ -436,6 +444,44 @@ static int get_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  	return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)) ? -EFAULT : 0;
>  }
>  
> +static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu)
> +{
> +	/* Only the first slice ever exists, for now */
> +	const unsigned int slices = 1;
> +
> +	if (!vcpu_has_sve(vcpu))
> +		return 0;
> +
> +	return slices * (SVE_NUM_PREGS + SVE_NUM_ZREGS + 1 /* FFR */);
> +}
> +
> +static int copy_sve_reg_indices(const struct kvm_vcpu *vcpu, u64 __user **uind)
> +{
> +	/* Only the first slice ever exists, for now */
> +	const unsigned int slices = 1;
> +	unsigned int i, n;
> +
> +	if (!vcpu_has_sve(vcpu))
> +		return 0;
> +
> +	for (i = 0; i < slices; i++) {
> +		for (n = 0; n < SVE_NUM_ZREGS; n++) {
> +			if (put_user(KVM_REG_ARM64_SVE_ZREG(n, i), (*uind)++))
> +				return -EFAULT;
> +		}
> +
> +		for (n = 0; n < SVE_NUM_PREGS; n++) {
> +			if (put_user(KVM_REG_ARM64_SVE_PREG(n, i), (*uind)++))
> +				return -EFAULT;
> +		}
> +
> +		if (put_user(KVM_REG_ARM64_SVE_FFR(i), (*uind)++))
> +			return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
>  /**
>   * kvm_arm_num_regs - how many registers do we present via KVM_GET_ONE_REG
>   *
> @@ -446,6 +492,7 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
>  	unsigned long res = 0;
>  
>  	res += num_core_regs(vcpu);
> +	res += num_sve_regs(vcpu);
>  	res += kvm_arm_num_sys_reg_descs(vcpu);
>  	res += kvm_arm_get_fw_num_regs(vcpu);
>  	res += NUM_TIMER_REGS;
> @@ -466,6 +513,10 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = copy_sve_reg_indices(vcpu, &uindices);
> +	if (ret)
> +		return ret;
> +
>  	ret = kvm_arm_copy_fw_reg_indices(vcpu, uindices);
>  	if (ret)
>  		return ret;
> 

-- 
Julien Thierry


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