Re: [PATCH v14 32/44] KVM: arm64: Handle Realm PSCI requests

[Steven Price <steven.price@arm.com>]

On 28/05/2026 07:55, Gavin Shan wrote:
> Hi Steve,
> 
> On 5/13/26 11:17 PM, Steven Price wrote:
>> The RMM needs to be informed of the target REC when a PSCI call is made
>> with an MPIDR argument.
>>
>> This requirement will be removed in a future release of the RMM 2.0
>> specification but is still required for v2.0-bet1.
>>
>> Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>> Chanegs 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:
>>   * Chance 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 |  3 ++
>>   arch/arm64/kvm/psci.c            | 15 ++++++++-
>>   arch/arm64/kvm/rmi.c             | 58 ++++++++++++++++++++++++++++++++
>>   3 files changed, 75 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/
>> asm/kvm_rmi.h
>> index b65cfec10dee..eacf82a7467d 100644
>> --- a/arch/arm64/include/asm/kvm_rmi.h
>> +++ b/arch/arm64/include/asm/kvm_rmi.h
>> @@ -109,6 +109,9 @@ int realm_map_non_secure(struct realm *realm,
>>                unsigned long size,
>>                enum kvm_pgtable_prot prot,
>>                struct kvm_mmu_memory_cache *memcache);
>> +int realm_psci_complete(struct kvm_vcpu *source,
>> +            struct kvm_vcpu *target,
>> +            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..a2cd55dc7b5b 100644
>> --- a/arch/arm64/kvm/psci.c
>> +++ b/arch/arm64/kvm/psci.c
>> @@ -103,7 +103,6 @@ static unsigned long kvm_psci_vcpu_on(struct
>> kvm_vcpu *source_vcpu)
>>         reset_state->reset = true;
>>       kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
>> -
> 
> This change isn't supposed to be part of this patch :-)

Whoops - indeed it isn't!

>>       /*
>>        * Make sure the reset request is observed if the RUNNABLE
>> mp_state is
>>        * observed.
>> @@ -142,6 +141,20 @@ 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;
>> +    }
>> +
>>       /*
>>        * 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 761b38a4071c..2b03e962ee41 100644
>> --- a/arch/arm64/kvm/rmi.c
>> +++ b/arch/arm64/kvm/rmi.c
>> @@ -3,6 +3,7 @@
>>    * Copyright (C) 2023-2025 ARM Ltd.
>>    */
>>   +#include <uapi/linux/psci.h>
>>   #include <linux/kvm_host.h>
>>     #include <asm/kvm_emulate.h>
>> @@ -127,6 +128,25 @@ 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, struct kvm_vcpu
>> *target,
>> +            unsigned long status)
>> +{
>> +    int ret;
>> +
>> +    /*
>> +     * XXX: RMM-v2.0 doesn't require the target REC address for
>> completing
>> +     * PSCI requests. Temporary hack until RMM implementation catches up
>> +     * to the full spec.
>> +     */
>> +    ret = rmi_psci_complete(virt_to_phys(source->arch.rec.rec_page),
>> +                virt_to_phys(target->arch.rec.rec_page),
>> +                status);
>> +    if (ret)
>> +        return -EINVAL;
> 
>         return -ENXIO;

Ack, although as the comment says this should be going away.

Thanks,
Steve

>> +
>> +    return 0;
>> +}
>> +
>>   static int realm_rtt_create(struct realm *realm,
>>                   unsigned long addr,
>>                   int level,
>> @@ -1004,6 +1024,41 @@ 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);
>> +    struct kvm_vcpu *target;
>> +
>> +    switch (run->exit.gprs[0]) {
>> +    /*
>> +     * XXX: RMM-v2.0 doesn't cause RMI_EXIT_PSCI for AFFINITY_INFO
>> +     * Temporary hack until tf-RMM gets the REC to MPIDR mapping via
>> +     * RD Auxiliary granules.
>> +     * For now always report SUCCESS
>> +     */
>> +    case PSCI_0_2_FN64_AFFINITY_INFO:
>> +        status = PSCI_RET_SUCCESS;
>> +        break;
>> +    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;
>> +    }
>> +
>> +    target = kvm_mpidr_to_vcpu(vcpu->kvm, run->exit.gprs[1]);
>> +    /* RMM makes sure that we don't get RMI_EXIT_PSCI for invalid
>> mpidrs */
>> +    if (target)
>> +        realm_psci_complete(vcpu, target, status);
>> +}
>> +
>>   /*
>>    * kvm_rec_pre_enter - Complete operations before entering a REC
>>    *
>> @@ -1028,6 +1083,9 @@ 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;
> 
> Thanks,
> Gavin
>