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V" , Emi Kisanuki , Vishal Annapurve References: <20251217101125.91098-1-steven.price@arm.com> <20251217101125.91098-12-steven.price@arm.com> <86seai8fbd.wl-maz@kernel.org> From: Steven Price Content-Language: en-GB In-Reply-To: <86seai8fbd.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260302_163112_097463_9C1C5FD6 X-CRM114-Status: GOOD ( 26.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 02/03/2026 14:40, Marc Zyngier wrote: > On Wed, 17 Dec 2025 10:10:48 +0000, > Steven Price wrote: >> >> When a VCPU migrates to another physical CPU check > > To another physical CPU? > > That's not what kvm_arch_vcpu_run_pid_change() tracks. It really is > limited to a new PID being associated to the vpcu thread. Which is > indeed the case when the vpcu runs for the first time, but that's > about it. > > If you need to track the physical CPU, we have some tracking for it in > vcpu_load(), but that'd need some rework. Sorry that was just a complete brainfart when I wrote that commit message. We don't care about physical CPUs - this is just catching the first VCPU run. Thanks for catching that. >> if this is the first >> time the guest has run, and if so activate the realm. >> >> Before the realm can be activated it must first be created, this is a >> stub in this patch and will be filled in by a later patch. >> >> Signed-off-by: Steven Price >> --- >> New patch for v12 >> --- >> arch/arm64/include/asm/kvm_rmi.h | 1 + >> arch/arm64/kvm/arm.c | 6 +++++ >> arch/arm64/kvm/rmi.c | 42 ++++++++++++++++++++++++++++++++ >> 3 files changed, 49 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h >> index cb7350f8a01a..e4534af06d96 100644 >> --- a/arch/arm64/include/asm/kvm_rmi.h >> +++ b/arch/arm64/include/asm/kvm_rmi.h >> @@ -69,6 +69,7 @@ void kvm_init_rmi(void); >> u32 kvm_realm_ipa_limit(void); >> >> int kvm_init_realm_vm(struct kvm *kvm); >> +int kvm_activate_realm(struct kvm *kvm); >> void kvm_destroy_realm(struct kvm *kvm); >> void kvm_realm_destroy_rtts(struct kvm *kvm); >> >> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c >> index 941d1bec8e77..542df37b9e82 100644 >> --- a/arch/arm64/kvm/arm.c >> +++ b/arch/arm64/kvm/arm.c >> @@ -951,6 +951,12 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu) >> return ret; >> } >> >> + if (kvm_is_realm(vcpu->kvm)) { >> + ret = kvm_activate_realm(kvm); >> + if (ret) >> + return ret; >> + } >> + >> mutex_lock(&kvm->arch.config_lock); >> set_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags); >> mutex_unlock(&kvm->arch.config_lock); >> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c >> index e57e8b7eafa9..98929382c365 100644 >> --- a/arch/arm64/kvm/rmi.c >> +++ b/arch/arm64/kvm/rmi.c >> @@ -223,6 +223,48 @@ void kvm_realm_destroy_rtts(struct kvm *kvm) >> WARN_ON(realm_tear_down_rtt_range(realm, 0, (1UL << ia_bits))); >> } >> >> +static int realm_ensure_created(struct kvm *kvm) >> +{ >> + /* Provided in later patch */ >> + return -ENXIO; >> +} >> + >> +int kvm_activate_realm(struct kvm *kvm) >> +{ >> + struct realm *realm = &kvm->arch.realm; >> + int ret; >> + >> + if (!kvm_is_realm(kvm)) >> + return -ENXIO; > > nit: you already checked for this in caller. Ack >> + >> + if (kvm_realm_state(kvm) == REALM_STATE_ACTIVE) >> + return 0; > > You probably also want to return early once the realm has been marked > as dead -- it shouldn't be able to be a zombie and die twice. Indeed, >= would be a better check. Thanks, Steve >> + >> + guard(mutex)(&kvm->arch.config_lock); >> + /* Check again with the lock held */ >> + if (kvm_realm_state(kvm) == REALM_STATE_ACTIVE) >> + return 0; >> + >> + ret = realm_ensure_created(kvm); >> + if (ret) >> + return ret; >> + >> + /* Mark state as dead in case we fail */ >> + WRITE_ONCE(realm->state, REALM_STATE_DEAD); >> + >> + if (!irqchip_in_kernel(kvm)) { >> + /* Userspace irqchip not yet supported with realms */ >> + return -EOPNOTSUPP; >> + } >> + >> + ret = rmi_realm_activate(virt_to_phys(realm->rd)); >> + if (ret) >> + return -ENXIO; >> + >> + WRITE_ONCE(realm->state, REALM_STATE_ACTIVE); >> + return 0; >> +} >> + >> void kvm_destroy_realm(struct kvm *kvm) >> { >> struct realm *realm = &kvm->arch.realm; > > Thanks, > > M. >