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V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo Pieralisi References: <20261102141304.126883-1-steven.price@arm.com> <20261102141304.126883-7-steven.price@arm.com> From: Suzuki K Poulose In-Reply-To: <20261102141304.126883-7-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Steven On 02/11/2026 14:12, Steven Price wrote: > 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 > --- > arch/arm64/include/asm/kvm_rmi.h | 20 ++++++++++++ > arch/arm64/kvm/arm.c | 9 +++++ > arch/arm64/kvm/mmu.c | 18 ++++++++-- > arch/arm64/kvm/rmi.c | 56 ++++++++++++++++++++++++++++++++ > 4 files changed, 101 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h > index 3194daaacf2b..f1a1ed6b91f5 100644 > --- a/arch/arm64/include/asm/kvm_rmi.h > +++ b/arch/arm64/include/asm/kvm_rmi.h > @@ -6,6 +6,9 @@ > #ifndef __ASM_KVM_RMI_H > #define __ASM_KVM_RMI_H > > +#include > +#include > + > /** > * enum realm_state - State of a Realm > * > @@ -50,12 +53,29 @@ enum realm_state { > /** > * struct realm - Additional per VM data for a Realm > * > + * @rd: Kernel mapping of the RMM-managed Realm Descriptor (RD) granule > + * @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; > + /* > + * 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 c8599fed5902..9a7bbfaf9675 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -303,6 +303,13 @@ 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_vm_is_realm(kvm)) { > + ret = kvm_init_realm(kvm); > + if (ret) > + goto err_uninit_mmu; > + } > + > return 0; > > err_uninit_mmu: > @@ -367,6 +374,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm) > > kvm_destroy_nested(kvm); > kvm_arm_teardown_hypercalls(kvm); > + if (kvm_vm_is_realm(kvm)) > + kvm_destroy_realm(kvm); > } > > static bool kvm_has_full_ptr_auth(void) > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 1301c563d705..b049ea67d9af 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -981,10 +981,14 @@ 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_vm_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; > @@ -1034,9 +1038,18 @@ 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_vm_is_realm(kvm)) > + stage2_destroy_range(pgt, 0, BIT(ia_bits)); > + > KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt); > } This looks like a good candidate for another callback for vm_s2_ops ? Something like (incomplete functionally, but this should work). As a bonus, we can remove two instances of KVM_PGT_FN() diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 5e9c2919c509..96685c52fb6e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1048,35 +1048,52 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type) * cond_resched() periodically to prevent hogging the CPU for a long time * and schedule something else, if required. */ -static void stage2_destroy_range(struct kvm_pgtable *pgt, phys_addr_t addr, - phys_addr_t end) +static void stage2_destroy_range(struct kvm_pgtable *pgt, + void (*pgt_destroy_range_fn)(struct kvm_pgtable *pgt, + u64 addr, u64 size)) { + u64 addr = 0; + u64 end = BIT(VTCR_EL2_IPA(pgt->mmu->vtcr)); u64 next; do { next = stage2_range_addr_end(addr, end); - KVM_PGT_FN(kvm_pgtable_stage2_destroy_range)(pgt, addr, - next - addr); + pgt_destroy_range_fn(pgt, addr, next - addr); if (next != end) cond_resched(); } while (addr = next, addr != end); } +static void kvm_vm_stage2_destroy(struct kvm_pgtable *pgt) +{ + stage2_destroy_range(pgt, kvm_pgtable_stage2_destroy_range); + kvm_pgtable_stage2_destroy_pgd(pgt); +} + +static void pkvm_stage2_destroy(struct kvm_pgtable *pgt) +{ + stage2_destroy_range(pgt, kvm_pgtable_stage2_destroy_range); + pkvm_pgtable_stage2_destroy_pgd(pgt); +} + +/* +* 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. +*/ +static void realm_stage2_destroy(struct kvm_pgtable *pgt, + u64 start, u64 end) +{ + kvm_pgtable_destroy_pgd(pgt); +} + 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); - /* - * 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_vm_is_realm(kvm)) - stage2_destroy_range(pgt, 0, BIT(ia_bits)); - - KVM_PGT_FN(kvm_pgtable_stage2_destroy_pgd)(pgt); + kvm->arch.vm_s2_ops->stage2_destroy(pgt, 0, BIT(ia_bits)); } > @@ -1084,6 +1097,8 @@ 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; > @@ -1092,7 +1107,6 @@ 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 5b07beff8bc9..45ecbaa467d1 100644 > --- a/arch/arm64/kvm/rmi.c > +++ b/arch/arm64/kvm/rmi.c > @@ -6,6 +6,8 @@ > #include > #include > > +#include > +#include > #include > #include > > @@ -14,6 +16,60 @@ 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 (!kvm_realm_is_created(kvm)) { > + kfree(realm->sro); > + realm->sro = NULL; > + return; > + } Do we leak memory of the stage2 PGD if the Realm was never created ? Should we have something like on top ? @@ -1646,11 +1645,8 @@ void kvm_destroy_realm(struct kvm *kvm) guard(mutex)(&kvm->arch.config_lock); - if (!kvm_realm_is_created(kvm)) { - kfree(realm->sro); - realm->sro = NULL; - return; - } + if (!kvm_realm_is_created(kvm)) + goto free_pgd; kvm_set_realm_state(kvm, REALM_STATE_DYING); @@ -1684,6 +1680,7 @@ void kvm_destroy_realm(struct kvm *kvm) kvm_set_realm_state(kvm, REALM_STATE_DEAD); +free_pgd: /* Now that the realm is destroyed, free the entry-level RTTs. */ kvm_free_stage2_pgd(&kvm->arch.mmu); Suzuki > + > + 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; > + rmi_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->sro = kmalloc_obj(*realm->sro); > + if (!realm->sro) > + return -ENOMEM; > + > + return 0; > +} > + > static int rmm_check_features(void) > { > if (kvm_lpa2_is_enabled() &&