On 29/05/2025 05:52, Emi Kisanuki (Fujitsu) wrote:
> Hello, I comment below.
Hi Emi,
>> Subject: [PATCH v8 16/43] arm64: RME: Handle realm enter/exit
>>
>> Entering a realm is done using a SMC call to the RMM. On exit the exit-codes
>> need to be handled slightly differently to the normal KVM path so define our own
>> functions for realm enter/exit and hook them in if the guest is a realm guest.
>>
>> Signed-off-by: Steven Price <steven.price@xxxxxxx>
>> ---
[..]
>> +/*
>> + * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason)
>> +on
>> + * proper exit to userspace.
>> + */
>> +int handle_rec_exit(struct kvm_vcpu *vcpu, int rec_run_ret) {
>> + struct realm_rec *rec = &vcpu->arch.rec;
>> + u8 esr_ec = ESR_ELx_EC(rec->run->exit.esr);
>> + unsigned long status, index;
>> +
>> + status = RMI_RETURN_STATUS(rec_run_ret);
>> + index = RMI_RETURN_INDEX(rec_run_ret);
>> +
>> + /*
>> + * If a PSCI_SYSTEM_OFF request raced with a vcpu executing, we
>> might
>> + * see the following status code and index indicating an attempt to run
>> + * a REC when the RD state is SYSTEM_OFF. In this case, we just need
>> to
>> + * return to user space which can deal with the system event or will try
>> + * to run the KVM VCPU again, at which point we will no longer attempt
>> + * to enter the Realm because we will have a sleep request pending on
>> + * the VCPU as a result of KVM's PSCI handling.
>> + */
>> + if (status == RMI_ERROR_REALM && index == 1) {
>> + vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
>> + return 0;
>> + }
> Running kvm-unit-tests-cca selftest(smp) test in quick succession may trigger these conditions, resulting in the following error logs.
> Error: KVM exit reason: 0 ("KVM_EXIT_UNKNOWN")
>
> Since KVM_EXIT_UNKNOWN is used when no specific exit reason applies, I think it would be better to make it identifiable as an error.
> How about adding and setting a new ARM64 exit_reason value to indicate that the PSCI_SYSTEM_OFF request is conflicting with a running vcpu?
Aneesh pointed this out to me off-list. We agreed that KVM_EXIT_SHUTDOWN
was more appropriate here. I'll make the change for v9.
Thanks,
Steve
> Best Regards,
> Emi Kisanuki
>> +
>> + if (rec_run_ret)
>> + return -ENXIO;
>> +
>> + vcpu->arch.fault.esr_el2 = rec->run->exit.esr;
>> + vcpu->arch.fault.far_el2 = rec->run->exit.far;
>> + vcpu->arch.fault.hpfar_el2 = rec->run->exit.hpfar;
>> +
>> + update_arch_timer_irq_lines(vcpu);
>> +
>> + /* Reset the emulation flags for the next run of the REC */
>> + rec->run->enter.flags = 0;
>> +
>> + switch (rec->run->exit.exit_reason) {
>> + case RMI_EXIT_SYNC:
>> + return rec_exit_handlers[esr_ec](vcpu);
>> + case RMI_EXIT_IRQ:
>> + case RMI_EXIT_FIQ:
>> + return 1;
>> + case RMI_EXIT_PSCI:
>> + return rec_exit_psci(vcpu);
>> + case RMI_EXIT_RIPAS_CHANGE:
>> + return rec_exit_ripas_change(vcpu);
>> + }
>> +
>> + kvm_pr_unimpl("Unsupported exit reason: %u\n",
>> + rec->run->exit.exit_reason);
>> + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>> + return 0;
>> +}
>> diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c index
>> 33eb793d8bdb..bee9dfe12e03 100644
>> --- a/arch/arm64/kvm/rme.c
>> +++ b/arch/arm64/kvm/rme.c
>> @@ -863,6 +863,25 @@ void kvm_destroy_realm(struct kvm *kvm)
>> kvm_free_stage2_pgd(&kvm->arch.mmu);
>> }
>>
>> +int kvm_rec_enter(struct kvm_vcpu *vcpu) {
>> + struct realm_rec *rec = &vcpu->arch.rec;
>> +
>> + switch (rec->run->exit.exit_reason) {
>> + case RMI_EXIT_HOST_CALL:
>> + case RMI_EXIT_PSCI:
>> + for (int i = 0; i < REC_RUN_GPRS; i++)
>> + rec->run->enter.gprs[i] = vcpu_get_reg(vcpu, i);
>> + break;
>> + }
>> +
>> + if (kvm_realm_state(vcpu->kvm) != REALM_STATE_ACTIVE)
>> + return -EINVAL;
>> +
>> + return rmi_rec_enter(virt_to_phys(rec->rec_page),
>> + virt_to_phys(rec->run));
>> +}
>> +
>> static void free_rec_aux(struct page **aux_pages,
>> unsigned int num_aux)
>> {
>> --
>> 2.43.0
>>
>
