Re: [PATCH v6 3/9] KVM: arm64: Add standard hypervisor firmware register

[Gavin Shan <gshan@xxxxxxxxxx>]

On 4/23/22 8:03 AM, Raghavendra Rao Ananta wrote:
> Introduce the firmware register to hold the standard hypervisor
> service calls (owner value 5) as a bitmap. The bitmap represents
> the features that'll be enabled for the guest, as configured by
> the user-space. Currently, this includes support only for
> Paravirtualized time, represented by bit-0.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> ---
>   arch/arm64/include/asm/kvm_host.h |  2 ++
>   arch/arm64/include/uapi/asm/kvm.h |  3 +++
>   arch/arm64/kvm/hypercalls.c       | 21 ++++++++++++++++++---
>   include/kvm/arm_hypercalls.h      |  2 ++
>   4 files changed, 25 insertions(+), 3 deletions(-)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>

> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index df07f4c10197..27d4b2a7970e 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -105,9 +105,11 @@ struct kvm_arch_memory_slot {
>    * struct kvm_smccc_features: Descriptor the hypercall services exposed to the guests
>    *
>    * @std_bmap: Bitmap of standard secure service calls
> + * @std_hyp_bmap: Bitmap of standard hypervisor service calls
>    */
>   struct kvm_smccc_features {
>   	unsigned long std_bmap;
> +	unsigned long std_hyp_bmap;
>   };
>   
>   struct kvm_arch {
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 0b79d2dc6ffd..9eecc7ee8c14 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -341,6 +341,9 @@ struct kvm_arm_copy_mte_tags {
>   #define KVM_REG_ARM_STD_BMAP			KVM_REG_ARM_FW_FEAT_BMAP_REG(0)
>   #define KVM_REG_ARM_STD_BIT_TRNG_V1_0		0
>   
> +#define KVM_REG_ARM_STD_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(1)
> +#define KVM_REG_ARM_STD_HYP_BIT_PV_TIME		0
> +
>   /* Device Control API: ARM VGIC */
>   #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
>   #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index df55a04d2fe8..f097bebdad39 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -72,8 +72,6 @@ static bool kvm_hvc_call_default_allowed(struct kvm_vcpu *vcpu, u32 func_id)
>   	 */
>   	case ARM_SMCCC_VERSION_FUNC_ID:
>   	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
> -	case ARM_SMCCC_HV_PV_TIME_FEATURES:
> -	case ARM_SMCCC_HV_PV_TIME_ST:
>   	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
>   	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
>   	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
> @@ -95,6 +93,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
>   	case ARM_SMCCC_TRNG_RND64:
>   		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_bmap,
>   						KVM_REG_ARM_STD_BIT_TRNG_V1_0);
> +	case ARM_SMCCC_HV_PV_TIME_FEATURES:
> +	case ARM_SMCCC_HV_PV_TIME_ST:
> +		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_hyp_bmap,
> +					KVM_REG_ARM_STD_HYP_BIT_PV_TIME);
>   	default:
>   		return kvm_hvc_call_default_allowed(vcpu, func_id);
>   	}
> @@ -102,6 +104,7 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
>   
>   int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>   {
> +	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
>   	u32 func_id = smccc_get_function(vcpu);
>   	u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
>   	u32 feature;
> @@ -165,7 +168,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>   			}
>   			break;
>   		case ARM_SMCCC_HV_PV_TIME_FEATURES:
> -			val[0] = SMCCC_RET_SUCCESS;
> +			if (kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_hyp_bmap,
> +					KVM_REG_ARM_STD_HYP_BIT_PV_TIME))
> +				val[0] = SMCCC_RET_SUCCESS;
>   			break;
>   		}
>   		break;
> @@ -211,6 +216,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
>   	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
>   	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
>   	KVM_REG_ARM_STD_BMAP,
> +	KVM_REG_ARM_STD_HYP_BMAP,
>   };
>   
>   void kvm_arm_init_hypercalls(struct kvm *kvm)
> @@ -218,6 +224,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
>   	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
>   
>   	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
> +	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
>   }
>   
>   int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> @@ -307,6 +314,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>   	case KVM_REG_ARM_STD_BMAP:
>   		val = READ_ONCE(smccc_feat->std_bmap);
>   		break;
> +	case KVM_REG_ARM_STD_HYP_BMAP:
> +		val = READ_ONCE(smccc_feat->std_hyp_bmap);
> +		break;
>   	default:
>   		return -ENOENT;
>   	}
> @@ -329,6 +339,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
>   		fw_reg_bmap = &smccc_feat->std_bmap;
>   		fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
>   		break;
> +	case KVM_REG_ARM_STD_HYP_BMAP:
> +		fw_reg_bmap = &smccc_feat->std_hyp_bmap;
> +		fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
> +		break;
>   	default:
>   		return -ENOENT;
>   	}
> @@ -430,6 +444,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>   
>   		return 0;
>   	case KVM_REG_ARM_STD_BMAP:
> +	case KVM_REG_ARM_STD_HYP_BMAP:
>   		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
>   	default:
>   		return -ENOENT;
> diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
> index 499b45b607b6..aadd6ae3ab72 100644
> --- a/include/kvm/arm_hypercalls.h
> +++ b/include/kvm/arm_hypercalls.h
> @@ -8,8 +8,10 @@
>   
>   /* Last valid bits of the bitmapped firmware registers */
>   #define KVM_REG_ARM_STD_BMAP_BIT_MAX		0
> +#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX	0
>   
>   #define KVM_ARM_SMCCC_STD_FEATURES		GENMASK(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
> +#define KVM_ARM_SMCCC_STD_HYP_FEATURES		GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
>   
>   int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
>