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V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo Pieralisi Subject: [PATCH v15 07/37] KVM: arm64: CCA: Add basic infrastructure for creating a realm Date: Wed, 15 Jul 2026 15:28:09 +0100 Message-ID: <20260715142841.80544-8-steven.price@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260715142841.80544-1-steven.price@arm.com> References: <20260715142841.80544-1-steven.price@arm.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce the skeleton functions for creating and destroying a realm. The IPA size requested is checked against what the RMM supports. The actual work of constructing the realm will be added in future patches. Signed-off-by: Steven Price --- Changes since v14: * Adapt to the RMM v2.0-bet2 realm parameter layout and SRO-based realm creation. Changes since v13: * Rebased and updated to RMM-v2.0-bet1. * Auxiliary granules have been removed in RMM-v2.0-bet1 Changes since v12: * Drop the RMM_PAGE_{SHIFT,SIZE} defines - the RMM is now configured to be the same as the host's page size. * Rework delegate/undelegate functions to use the new RMI range based operations. Changes since v11: * Major rework to drop the realm configuration and make the construction of realms implicit rather than driven by the VMM directly. * The code to create RDs, handle VMIDs etc is moved to later patches. Changes since v10: * Rename from RME to RMI. * Move the stage2 cleanup to a later patch. Changes since v9: * Avoid walking the stage 2 page tables when destroying the realm - the real ones are not accessible to the non-secure world, and the RMM may leave junk in the physical pages when returning them. * Fix an error path in realm_create_rd() to actually return an error value. Changes since v8: * Fix free_delegated_granule() to not call kvm_account_pgtable_pages(); a separate wrapper will be introduced in a later patch to deal with RTTs. * Minor code cleanups following review. Changes since v7: * Minor code cleanup following Gavin's review. Changes since v6: * Separate RMM RTT calculations from host PAGE_SIZE. This allows the host page size to be larger than 4k while still communicating with an RMM which uses 4k granules. Changes since v5: * Introduce free_delegated_granule() to replace many undelegate/free_page() instances and centralise the comment on leaking when the undelegate fails. * Several other minor improvements suggested by reviews - thanks for the feedback! Changes since v2: * Improved commit description. * Improved return failures for rmi_check_version(). * Clear contents of PGD after it has been undelegated in case the RMM left stale data. * Minor changes to reflect changes in previous patches. --- arch/arm64/include/asm/kvm_emulate.h | 24 ++++++++++ arch/arm64/include/asm/kvm_rmi.h | 65 +++++++++++++++++++++++++++ arch/arm64/kvm/arm.c | 12 +++++ arch/arm64/kvm/mmu.c | 18 +++++++- arch/arm64/kvm/rmi.c | 67 ++++++++++++++++++++++++++++ 5 files changed, 184 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 5bf3d7e1d92c..e26d6755279f 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -688,4 +688,28 @@ static inline void vcpu_set_hcrx(struct kvm_vcpu *vcpu) vcpu->arch.hcrx_el2 |= HCRX_EL2_EnASR; } } + +static inline bool kvm_is_realm(struct kvm *kvm) +{ + if (static_branch_unlikely(&kvm_rmi_is_available)) + return kvm->arch.is_realm; + return false; +} + +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_is_realm(kvm) && kvm_realm_state(kvm) != REALM_STATE_NONE; +} + #endif /* __ARM64_KVM_EMULATE_H__ */ diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h index 57d24b244c95..5c40616aa1a1 100644 --- a/arch/arm64/include/asm/kvm_rmi.h +++ b/arch/arm64/include/asm/kvm_rmi.h @@ -6,12 +6,77 @@ #ifndef __ASM_KVM_RMI_H #define __ASM_KVM_RMI_H +#include + +/** + * 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. + */ + 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, + /** + * @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 + * + * @rd: Kernel mapping of the RMM-managed Realm Descriptor (RD) granule + * @params: Parameters for the RMI_REALM_CREATE command + * @sro: Preallocated SRO state context for Realm MMU operations + * @state: The lifetime state machine for the realm + * @ia_bits: Number of valid Input Address bits in the IPA */ struct realm { + void *rd; + struct realm_params *params; + /* + * Reused by RTT map/unmap SRO commands. Those commands are only + * issued from Realm stage-2 map/unmap paths while kvm->mmu_lock is + * held for write, including Realm fault handling where + * kvm_fault_lock() takes the write side, so concurrent use is + * serialized. + */ + struct rmi_sro_state *sro; + enum realm_state state; + unsigned int ia_bits; }; void kvm_init_rmi(void); +u32 kvm_rmm_ipa_limit(void); + +int kvm_init_realm(struct kvm *kvm); +void kvm_destroy_realm(struct kvm *kvm); #endif /* __ASM_KVM_RMI_H */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index b961c22fce3d..c4d906861736 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -266,6 +266,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) bitmap_zero(kvm->arch.vcpu_features, KVM_VCPU_MAX_FEATURES); + /* Initialise the realm bits after the generic bits are enabled */ + if (kvm_is_realm(kvm)) { + ret = kvm_init_realm(kvm); + if (ret) + goto err_uninit_mmu; + } + return 0; err_uninit_mmu: @@ -328,6 +335,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm_unshare_hyp(kvm, kvm + 1); kvm_arm_teardown_hypercalls(kvm); + if (kvm_is_realm(kvm)) + kvm_destroy_realm(kvm); } static bool kvm_has_full_ptr_auth(void) @@ -488,6 +497,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) else r = kvm_supports_cacheable_pfnmap(); break; + case KVM_CAP_ARM_RMI: + r = static_key_enabled(&kvm_rmi_is_available); + break; default: r = 0; diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 6c941aaa10c6..8b9efa8a3539 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -904,10 +904,14 @@ static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = { static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type) { + struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); u32 kvm_ipa_limit = get_kvm_ipa_limit(); u64 mmfr0, mmfr1; u32 phys_shift; + if (kvm_is_realm(kvm)) + kvm_ipa_limit = kvm_rmm_ipa_limit(); + phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type); if (is_protected_kvm_enabled()) { phys_shift = kvm_ipa_limit; @@ -957,9 +961,18 @@ static void stage2_destroy_range(struct kvm_pgtable *pgt, phys_addr_t addr, static void kvm_stage2_destroy(struct kvm_pgtable *pgt) { + struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu); unsigned int ia_bits = VTCR_EL2_IPA(pgt->mmu->vtcr); - stage2_destroy_range(pgt, 0, BIT(ia_bits)); + /* + * Realm RTTs are inaccessible to the host and may contain stale data + * after the RMM has released them. The non-root RTTs are explicitly + * destroyed through RMI before the RD is destroyed; only the root PGD + * pages remain to be freed here. + */ + if (!kvm_is_realm(kvm)) + stage2_destroy_range(pgt, 0, BIT(ia_bits)); + KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt); } @@ -1001,6 +1014,8 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t return -EINVAL; } + mmu->arch = &kvm->arch; + err = kvm_init_ipa_range(mmu, type); if (err) return err; @@ -1009,7 +1024,6 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t if (!pgt) return -ENOMEM; - mmu->arch = &kvm->arch; err = KVM_PGT_FN(kvm_pgtable_stage2_init)(pgt, mmu, &kvm_s2_mm_ops); if (err) goto out_free_pgtable; diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c index 247c4f033945..b81c404ead9f 100644 --- a/arch/arm64/kvm/rmi.c +++ b/arch/arm64/kvm/rmi.c @@ -5,6 +5,8 @@ #include +#include +#include #include #include #include @@ -14,6 +16,71 @@ static bool rmi_has_feature(int reg, unsigned long feature) return !!u64_get_bits(rmi_feat_reg(reg), feature); } +u32 kvm_rmm_ipa_limit(void) +{ + return u64_get_bits(rmi_feat_reg(0), RMI_FEATURE_REGISTER_0_S2SZ); +} + +void kvm_destroy_realm(struct kvm *kvm) +{ + struct realm *realm = &kvm->arch.realm; + size_t pgd_size = kvm_pgtable_stage2_pgd_size(kvm->arch.mmu.vtcr); + + if (realm->params) { + free_page((unsigned long)realm->params); + realm->params = NULL; + } + + if (!kvm_realm_is_created(kvm)) { + kfree(realm->sro); + realm->sro = NULL; + return; + } + + kvm_set_realm_state(kvm, REALM_STATE_DYING); + + if (realm->rd) { + phys_addr_t rd_phys = virt_to_phys(realm->rd); + + if (WARN_ON(rmi_realm_terminate(rd_phys, realm->sro))) + return; + + if (WARN_ON(rmi_realm_destroy(rd_phys, realm->sro))) + return; + free_delegated_page(rd_phys); + realm->rd = NULL; + } + + if (WARN_ON(rmi_undelegate_range(kvm->arch.mmu.pgd_phys, + pgd_size))) + return; + + kvm_set_realm_state(kvm, REALM_STATE_DEAD); + + /* Now that the realm is destroyed, free the entry-level RTTs. */ + kvm_free_stage2_pgd(&kvm->arch.mmu); + + kfree(realm->sro); + realm->sro = NULL; +} + +int kvm_init_realm(struct kvm *kvm) +{ + struct realm *realm = &kvm->arch.realm; + + realm->params = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + realm->sro = kmalloc_obj(*realm->sro); + if (!realm->params || !realm->sro) { + free_page((unsigned long)realm->params); + kfree(realm->sro); + realm->params = NULL; + realm->sro = NULL; + return -ENOMEM; + } + + return 0; +} + static int rmm_check_features(void) { if (kvm_lpa2_is_enabled() && -- 2.43.0