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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a7e4b00de6sm5567281a91.1.2026.10.05.20.42.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Oct 2026 20:42:47 -0700 (PDT) Message-ID: <9bbb3b3c-522f-4deb-9f32-0fcf731dd0bb@redhat.com> Date: Tue, 6 Oct 2026 13:42:38 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v22 18/23] KVM: arm64: CCA: Introduce Realms To: Suzuki K Poulose , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, sudeep.holla@arm.com, jonathan.cameron@oss.qualcomm.com References: <20261005090754.2140522-1-suzuki.poulose@arm.com> <20261005090754.2140522-19-suzuki.poulose@arm.com> From: Gavin Shan In-Reply-To: <20261005090754.2140522-19-suzuki.poulose@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Qq48fCz8uX09p6zCKiOCwcG3bBm8agvkLImQOdpVqIM_1791258170 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261005_204253_124292_EF8E0F6A X-CRM114-Status: GOOD ( 40.13 ) 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 10/5/26 7:07 PM, Suzuki K Poulose wrote: > From: Steven Price > > Add foundational work for supporting Realms. > - Add a new VM flavor. > - At KVM init, check if the KVM can support Realms (though not functional > yet) and will be advertised by static key kvm_rmi_is_available. This > will be turned on in a later patches, once we have all the bits and > pieces ready. For now check if we are blessed with KVM_MODE_RMM. > - Add realm specific tracking in kvm_arch. Since Realm and protected pKVM > states are mutually exclusive, move them into a union. > > Please note that we cannot create Realm VMs yet. This requires further > changes to the UABI and core RMI driver support, which will come later. > > Reviewed-by: Jonathan Cameron > Signed-off-by: Steven Price > Co-developed-by: Suzuki K Poulose > Signed-off-by: Suzuki K Poulose > --- > arch/arm64/include/asm/kvm_emulate.h | 16 ++++++++ > arch/arm64/include/asm/kvm_host.h | 19 ++++++--- > arch/arm64/include/asm/kvm_rmi.h | 61 ++++++++++++++++++++++++++++ > arch/arm64/include/asm/virt.h | 1 + > arch/arm64/kvm/Makefile | 2 +- > arch/arm64/kvm/arm.c | 6 +++ > arch/arm64/kvm/mmu.c | 1 + > arch/arm64/kvm/rmi.c | 18 ++++++++ > 8 files changed, 118 insertions(+), 6 deletions(-) > create mode 100644 arch/arm64/include/asm/kvm_rmi.h > create mode 100644 arch/arm64/kvm/rmi.c > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index a3c1928bdf743..d360a8b05b8bf 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -793,4 +793,20 @@ static inline void kvm_reset_vcpu_psci(struct kvm_vcpu *vcpu, > vcpu_set_reg(vcpu, 0, reset_state->r0); > } > > +static inline enum realm_state kvm_realm_state(struct kvm *kvm) > +{ > + return READ_ONCE(kvm->arch.realm.state); > +} > + > +static inline void kvm_set_realm_state(struct kvm *kvm, > + enum realm_state new_state) > +{ > + WRITE_ONCE(kvm->arch.realm.state, new_state); > +} > + > +static inline bool kvm_realm_is_created(struct kvm *kvm) > +{ > + return kvm_vm_is_realm(kvm) && kvm_realm_state(kvm) != REALM_STATE_NONE; > +} > + > #endif /* __ARM64_KVM_EMULATE_H__ */ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index dfa9d4ec61a76..3debffef638a4 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > #include > > #define __KVM_HAVE_ARCH_INTC_INITIALIZED > @@ -334,6 +335,7 @@ enum kvm_arm_vm_flavor { > VM_PKVM, /* Normal guests on pKVM */ > MARKER(__VM_PROTECTED), > VM_PROTECTED_PKVM, /* Protected VM */ > + VM_REALM, /* CCA */ > VM_FLAVOR_MAX > }; > > @@ -450,11 +452,14 @@ struct kvm_arch { > /* Count the number of VNCR_EL2 TLBs */ > atomic_t vncr_tlb_count; > > - /* > - * For an untrusted host VM, 'pkvm.handle' is used to lookup > - * the associated pKVM instance in the hypervisor. > - */ > - struct kvm_protected_vm pkvm; > + union { > + /* > + * For an untrusted host VM, 'pkvm.handle' is used to lookup > + * the associated pKVM instance in the hypervisor. > + */ > + struct kvm_protected_vm pkvm; > + struct realm realm; > + }; > > #ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS > /* Nested virtualization info */ > @@ -1565,6 +1570,10 @@ struct kvm *kvm_arch_alloc_vm(void); > (__kvm && kvm_vm_is_protected_pkvm(__kvm)); \ > }) > > + > +#define kvm_vm_is_realm(kvm) ((kvm)->arch.vm_flavor == VM_REALM) > +#define vcpu_is_rec(vcpu) kvm_vm_is_realm((vcpu)->kvm) > + vcpu_is_rec() isn't safely called in nVHE hyp stub. So do we need add something similiar to what we had for vcpu_is_protected(vcpu) in PATCH[05]? #ifdef __KVM_NVHE_HYPERVISOR__ /* vcpu_is_rec() isn't expected to called in nVHE hyp stub */ #define vcpu_is_rec(vcpu) BUILD_BUG_ON(1) #else #define vcpu_is_rec(vcpu) kvm_vm_is_realm((vcpu)->kvm) #endif > #define kvm_vm_hyp_is_distrusting(kvm) ((kvm)->arch.vm_flavor >= __VM_DISTRUSTING_HYP) > > int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature); > diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h > new file mode 100644 > index 0000000000000..44f5c75a27b5b > --- /dev/null > +++ b/arch/arm64/include/asm/kvm_rmi.h > @@ -0,0 +1,61 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) 2023-2026 ARM Ltd. > + */ > + > +#ifndef __ASM_KVM_RMI_H > +#define __ASM_KVM_RMI_H > + > +/** > + * enum realm_state - State of a Realm > + * > + * Mirrors the RMM's Realm lifecycle states where they are meaningful to KVM, > + * with REALM_STATE_DYING being a KVM-internal state used to prevent further > + * requests while teardown is in progress. KVM does not track REALM_SYSTEM_OFF > + * or REALM_ZOMBIE separately as they naturally lead to teardown. > + */ > +enum realm_state { > + /** > + * @REALM_STATE_NONE: > + * Realm has not yet been created. rmi_realm_create() has not > + * yet been called. > + */ > + REALM_STATE_NONE, > + /** > + * @REALM_STATE_NEW: > + * Realm is under construction, rmi_realm_create() has been > + * called, but it is not yet activated. Pages may be populated. ^^^^^ Granule instead of page is the term applicable to RMM. Lets use a generic term 'memory' here. Also, lets mention the name of the function used to populate the memory (granules), which is consistent to the comments for REALM_STATE_ACTIVE. Memory may be populated by rmi_rtt_data_map_init(). > + */ > + REALM_STATE_NEW, > + /** > + * @REALM_STATE_ACTIVE: > + * Realm has been created and is eligible for execution with > + * rmi_rec_enter(). Pages may no longer be populated with > + * rmi_data_create(). > + */ > + REALM_STATE_ACTIVE, rmi_data_create() is an invalid function name. Memory can't longer be populated using rmi_rtt_data_map_init(). > + /** > + * @REALM_STATE_DYING: > + * Realm is in the process of being destroyed or has already been > + * destroyed. > + */ > + REALM_STATE_DYING, > + /** > + * @REALM_STATE_DEAD: > + * Realm has been destroyed. > + */ > + REALM_STATE_DEAD > +}; > + > +/** > + * struct realm - Additional per VM data for a Realm > + * > + * @state: The lifetime state machine for the realm > + */ > +struct realm { > + enum realm_state state; > +}; > + > +void kvm_init_rmi(void); > + > +#endif /* __ASM_KVM_RMI_H */ > diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h > index b546703c3ab9a..92cec42952f42 100644 > --- a/arch/arm64/include/asm/virt.h > +++ b/arch/arm64/include/asm/virt.h > @@ -87,6 +87,7 @@ void __hyp_reset_vectors(void); > bool is_kvm_arm_initialised(void); > > DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized); > +DECLARE_STATIC_KEY_FALSE(kvm_rmi_is_available); > > static inline bool is_pkvm_initialized(void) > { > diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile > index 59612d2f277c1..ed3cf30eb06e7 100644 > --- a/arch/arm64/kvm/Makefile > +++ b/arch/arm64/kvm/Makefile > @@ -16,7 +16,7 @@ CFLAGS_handle_exit.o += -Wno-override-init > kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \ > inject_fault.o va_layout.o handle_exit.o config.o \ > guest.o debug.o reset.o sys_regs.o stacktrace.o \ > - vgic-sys-reg-v3.o fpsimd.o pkvm.o \ > + vgic-sys-reg-v3.o fpsimd.o pkvm.o rmi.o \ > arch_timer.o trng.o vmid.o emulate-nested.o nested.o at.o \ > vgic/vgic.o vgic/vgic-init.o \ > vgic/vgic-irqfd.o vgic/vgic-v2.o \ > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 294cea4cc8271..37ef2ba4e43e2 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -42,6 +42,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -112,6 +113,8 @@ long kvm_get_cap_for_kvm_ioctl(unsigned int ioctl, long *ext) > return -EINVAL; > } > > +DEFINE_STATIC_KEY_FALSE(kvm_rmi_is_available); > + > DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector); > > DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base); > @@ -2239,6 +2242,7 @@ static const struct kvm_vcpu_ops *arm64_vcpu_ops[] = { > KVM_VCPU_OPS(VM_VHE, vhe_vcpu_ops), > KVM_VCPU_OPS(VM_PKVM, pkvm_vcpu_ops), > KVM_VCPU_OPS(VM_PROTECTED_PKVM, pkvm_vcpu_ops), > + KVM_VCPU_OPS(VM_REALM, realm_vcpu_ops), > }; > > static void kvm_init_vcpu_ops(struct kvm_vcpu *vcpu) > @@ -3192,6 +3196,8 @@ static __init int kvm_arm_init(void) > > in_hyp_mode = is_kernel_in_hyp_mode(); > > + kvm_init_rmi(); > + > if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE) || > cpus_have_final_cap(ARM64_WORKAROUND_1508412)) > kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \ > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 58bc6a85f48b4..697f1ba6667a9 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -2927,6 +2927,7 @@ static const struct kvm_vm_s2_ops *arm64_vm_s2_ops[] = { > KVM_VM_S2_OPS(VM_NVHE, kvm_default_vm_s2_ops), > KVM_VM_S2_OPS(VM_PKVM, pkvm_vm_s2_ops), > KVM_VM_S2_OPS(VM_PROTECTED_PKVM, protected_pkvm_vm_s2_ops), > + KVM_VM_S2_OPS(VM_REALM, realm_vm_s2_ops), > }; > > static int kvm_vm_init_vm_s2_ops(struct kvm *kvm) > diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c > new file mode 100644 > index 0000000000000..5ecc8b3498698 > --- /dev/null > +++ b/arch/arm64/kvm/rmi.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2023-2026 ARM Ltd. > + */ > + > +#include > + > +#include > + > +void kvm_init_rmi(void) > +{ > + if (kvm_get_mode() != KVM_MODE_RMM) > + return; > + > + /* TODO: Check if the RMI is available */ > + > + /* Future patch will enable static branch kvm_rmi_is_available */ > +} Thanks, Gavin