Re: [PATCH v15 25/37] KVM: arm64: CCA: Handle Realm PSCI requests

On 15/07/2026 15:28, Steven Price wrote:
> Some PSCI commands cause a REC exit and the host has to call
> RMI_PSCI_COMPLETE to provide the status value to return to the guest.
> 
> Co-developed-by: Suzuki K Poulose <[email protected]>
> Signed-off-by: Suzuki K Poulose <[email protected]>
> Signed-off-by: Steven Price <[email protected]>
> ---
> Changes since v14:
>   * Dropped the support for providing the target REC for a PSCI call (as
>     per v2.0-bet2 spec).
> Changes since v13:
>   * The ioctl KVM_ARM_VCPU_RMI_PSCI_COMPLETE has gone. The RMI call is
>     made automatically just before entering the REC again.
> Changes since v12:
>   * Change return code for non-realms to -ENXIO to better represent that
>     the ioctl is invalid for non-realms (checkpatch is insistent that
>     "ENOSYS means 'invalid syscall nr' and nothing else").
> Changes since v11:
>   * RMM->RMI renaming.
> Changes since v6:
>   * Use vcpu_is_rec() rather than kvm_is_realm(vcpu->kvm).
>   * Minor renaming/formatting fixes.
> ---
>   arch/arm64/include/asm/kvm_rmi.h |  2 ++
>   arch/arm64/kvm/psci.c            | 14 ++++++++++++
>   arch/arm64/kvm/rmi.c             | 38 ++++++++++++++++++++++++++++++++
>   3 files changed, 54 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h
> index 718c7128a3c3..a9bb9aabee5d 100644
> --- a/arch/arm64/include/asm/kvm_rmi.h
> +++ b/arch/arm64/include/asm/kvm_rmi.h
> @@ -120,6 +120,8 @@ int realm_map_ipa(struct kvm *kvm, phys_addr_t ipa,
>   		  enum kvm_pgtable_prot prot,
>   		  struct kvm_mmu_memory_cache *memcache);
>   
> +int realm_psci_complete(struct kvm_vcpu *source, unsigned long status);
> +
>   static inline bool kvm_realm_is_private_address(struct realm *realm,
>   						unsigned long addr)
>   {
> diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> index 3b5dbe9a0a0e..b0983ee416a2 100644
> --- a/arch/arm64/kvm/psci.c
> +++ b/arch/arm64/kvm/psci.c
> @@ -142,6 +142,20 @@ static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
>   	/* Ignore other bits of target affinity */
>   	target_affinity &= target_affinity_mask;
>   
> +	if (vcpu_is_rec(vcpu)) {
> +		struct kvm_vcpu *target_vcpu;
> +
> +		/* RMM supports only zero affinity level */
> +		if (lowest_affinity_level != 0)
> +			return PSCI_RET_INVALID_PARAMS;
> +
> +		target_vcpu = kvm_mpidr_to_vcpu(kvm, target_affinity);
> +		if (!target_vcpu)
> +			return PSCI_RET_INVALID_PARAMS;
> +
> +		return PSCI_RET_SUCCESS;
> +	}
> +

We don't have to deal with AFFINITY_INFO anymore with the RMM
maintaining the MPIDR to REC mapping. This can be removed.

Otherwise looks good to me.

Suzuki


>   	/*
>   	 * If one or more VCPU matching target affinity are running
>   	 * then ON else OFF
> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
> index 31effae067c8..8fb6403893e8 100644
> --- a/arch/arm64/kvm/rmi.c
> +++ b/arch/arm64/kvm/rmi.c
> @@ -3,6 +3,7 @@
>    * Copyright (C) 2023-2026 ARM Ltd.
>    */
>   
> +#include <uapi/linux/psci.h>
>   #include <linux/kvm_host.h>
>   
>   #include <asm/kvm_emulate.h>
> @@ -119,6 +120,18 @@ static void free_rtt(phys_addr_t phys)
>   	kvm_account_pgtable_pages(phys_to_virt(phys), -1);
>   }
>   
> +int realm_psci_complete(struct kvm_vcpu *source, unsigned long status)
> +{
> +	int ret;
> +
> +	ret = rmi_psci_complete(virt_to_phys(source->arch.rec.rec_page),
> +				status);
> +	if (ret)
> +		return -ENXIO;
> +
> +	return 0;
> +}
> +
>   static int realm_rtt_create(struct realm *realm,
>   			    unsigned long addr,
>   			    int level,
> @@ -1115,6 +1128,28 @@ static void kvm_complete_ripas_change(struct kvm_vcpu *vcpu)
>   	rec->run->exit.ripas_base = base;
>   }
>   
> +static void kvm_rec_complete_psci(struct kvm_vcpu *vcpu)
> +{
> +	struct rec_run *run = vcpu->arch.rec.run;
> +	unsigned long status = PSCI_RET_DENIED;
> +	unsigned long ret = vcpu_get_reg(vcpu, 0);
> +
> +	switch (run->exit.gprs[0]) {
> +	case PSCI_0_2_FN64_CPU_ON: {
> +		if (ret != PSCI_RET_SUCCESS &&
> +		    ret != PSCI_RET_ALREADY_ON)
> +			status = PSCI_RET_DENIED;
> +		else
> +			status = PSCI_RET_SUCCESS;
> +		break;
> +	}
> +	default:
> +		return;
> +	}
> +
> +	realm_psci_complete(vcpu, status);
> +}
> +
>   /*
>    * kvm_rec_pre_enter - Complete operations before entering a REC
>    *
> @@ -1139,6 +1174,9 @@ int kvm_rec_pre_enter(struct kvm_vcpu *vcpu)
>   		for (int i = 0; i < REC_RUN_GPRS; i++)
>   			rec->run->enter.gprs[i] = vcpu_get_reg(vcpu, i);
>   		break;
> +	case RMI_EXIT_PSCI:
> +		kvm_rec_complete_psci(vcpu);
> +		break;
>   	case RMI_EXIT_RIPAS_CHANGE:
>   		kvm_complete_ripas_change(vcpu);
>   		break;