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Tue, 28 Jan 2025 16:43:15 -0800 (PST) X-Google-Smtp-Source: AGHT+IGJjpgjrIHY7a3JC5Ez/0L8BHt6NxNYaYvhYnSyLULVqB3+oTe+OzhpQ9OQ+eLwfEAg4S+Arw== X-Received: by 2002:a17:90b:2743:b0:2ee:48bf:7dc9 with SMTP id 98e67ed59e1d1-2f83ac0068cmr1779946a91.15.1738111395620; Tue, 28 Jan 2025 16:43:15 -0800 (PST) Received: from [192.168.68.55] ([180.233.125.64]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2f83bfbf166sm218188a91.43.2025.01.28.16.43.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Jan 2025 16:43:15 -0800 (PST) Message-ID: <691a2f0a-0f04-4bf6-a11a-ea7ee753cf88@redhat.com> Date: Wed, 29 Jan 2025 10:43:06 +1000 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 08/43] arm64: RME: ioctls to create and configure realms To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20241212155610.76522-1-steven.price@arm.com> <20241212155610.76522-9-steven.price@arm.com> From: Gavin Shan In-Reply-To: <20241212155610.76522-9-steven.price@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: nO2oVe_xN9YVBS2TbPZLaKhRWDWte9u6IH0OakCK06Q_1738111396 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/13/24 1:55 AM, Steven Price wrote: > Add the KVM_CAP_ARM_RME_CREATE_RD ioctl to create a realm. This involves > delegating pages to the RMM to hold the Realm Descriptor (RD) and for > the base level of the Realm Translation Tables (RTT). A VMID also need > to be picked, since the RMM has a separate VMID address space a > dedicated allocator is added for this purpose. > > KVM_CAP_ARM_RME_CONFIG_REALM is provided to allow configuring the realm > before it is created. Configuration options can be classified as: > > 1. Parameters specific to the Realm stage2 (e.g. IPA Size, vmid, stage2 > entry level, entry level RTTs, number of RTTs in start level, LPA2) > Most of these are not measured by RMM and comes from KVM book > keeping. > > 2. Parameters controlling "Arm Architecture features for the VM". (e.g. > SVE VL, PMU counters, number of HW BRPs/WPs), configured by the VMM > using the "user ID register write" mechanism. These will be > supported in the later patches. > > 3. Parameters are not part of the core Arm architecture but defined > by the RMM spec (e.g. Hash algorithm for measurement, > Personalisation value). These are programmed via > KVM_CAP_ARM_RME_CONFIG_REALM. > > For the IPA size there is the possibility that the RMM supports a > different size to the IPA size supported by KVM for normal guests. At > the moment the 'normal limit' is exposed by KVM_CAP_ARM_VM_IPA_SIZE and > the IPA size is configured by the bottom bits of vm_type in > KVM_CREATE_VM. This means that it isn't easy for the VMM to discover > what IPA sizes are supported for Realm guests. Since the IPA is part of > the measurement of the realm guest the current expectation is that the > VMM will be required to pick the IPA size demanded by attestation and > therefore simply failing if this isn't available is fine. An option > would be to expose a new capability ioctl to obtain the RMM's maximum > IPA size if this is needed in the future. > > Co-developed-by: Suzuki K Poulose > Signed-off-by: Suzuki K Poulose > Signed-off-by: Steven Price > --- > 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 | 5 + > arch/arm64/include/asm/kvm_rme.h | 19 ++ > arch/arm64/kvm/arm.c | 18 ++ > arch/arm64/kvm/mmu.c | 22 +- > arch/arm64/kvm/rme.c | 296 +++++++++++++++++++++++++++ > 5 files changed, 358 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index 4d417e39763e..27f54a7778aa 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -715,6 +715,11 @@ static inline enum realm_state kvm_realm_state(struct kvm *kvm) > return READ_ONCE(kvm->arch.realm.state); > } > > +static inline bool kvm_realm_is_created(struct kvm *kvm) > +{ > + return kvm_is_realm(kvm) && kvm_realm_state(kvm) != REALM_STATE_NONE; > +} > + > static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu) > { > return false; > diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h > index 69af5c3a1e44..209cd99f03dd 100644 > --- a/arch/arm64/include/asm/kvm_rme.h > +++ b/arch/arm64/include/asm/kvm_rme.h > @@ -6,6 +6,8 @@ > #ifndef __ASM_KVM_RME_H > #define __ASM_KVM_RME_H > > +#include > + > /** > * enum realm_state - State of a Realm > */ > @@ -46,11 +48,28 @@ enum realm_state { > * struct realm - Additional per VM data for a Realm > * > * @state: The lifetime state machine for the realm > + * @rd: Kernel mapping of the Realm Descriptor (RD) > + * @params: Parameters for the RMI_REALM_CREATE command > + * @num_aux: The number of auxiliary pages required by the RMM > + * @vmid: VMID to be used by the RMM for the realm > + * @ia_bits: Number of valid Input Address bits in the IPA > */ > struct realm { > enum realm_state state; > + > + void *rd; > + struct realm_params *params; > + > + unsigned long num_aux; > + unsigned int vmid; > + unsigned int ia_bits; > }; > > void kvm_init_rme(void); > +u32 kvm_realm_ipa_limit(void); > + > +int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap); > +int kvm_init_realm_vm(struct kvm *kvm); > +void kvm_destroy_realm(struct kvm *kvm); > > #endif > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 93087eca9c51..2bbf30d66424 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -153,6 +153,13 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > } > mutex_unlock(&kvm->slots_lock); > break; > + case KVM_CAP_ARM_RME: > + if (!kvm_is_realm(kvm)) > + return -EINVAL; > + mutex_lock(&kvm->lock); > + r = kvm_realm_enable_cap(kvm, cap); > + mutex_unlock(&kvm->lock); > + break; > default: > break; > } The check of !kvm_is_realm() seems unnecessary because the same check will be done in kvm_realm_enable_cap(). > @@ -215,6 +222,13 @@ 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_vm(kvm); > + if (ret) > + goto err_free_cpumask; > + } > + > return 0; > > err_free_cpumask: > @@ -274,6 +288,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm) > kvm_unshare_hyp(kvm, kvm + 1); > > kvm_arm_teardown_hypercalls(kvm); > + kvm_destroy_realm(kvm); > } > > static bool kvm_has_full_ptr_auth(void) > @@ -421,6 +436,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES: > r = BIT(0); > break; > + case KVM_CAP_ARM_RME: > + r = static_key_enabled(&kvm_rme_is_available); > + break; > default: > r = 0; > } > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index c9d46ad57e52..f09d580c12ad 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -863,12 +863,16 @@ static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = { > .icache_inval_pou = invalidate_icache_guest_page, > }; > > -static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type) > +static int kvm_init_ipa_range(struct kvm *kvm, > + struct kvm_s2_mmu *mmu, unsigned long type) > { > u32 kvm_ipa_limit = get_kvm_ipa_limit(); > u64 mmfr0, mmfr1; > u32 phys_shift; > > + if (kvm_is_realm(kvm)) > + kvm_ipa_limit = kvm_realm_ipa_limit(); > + > if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK) > return -EINVAL; > > @@ -933,7 +937,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t > return -EINVAL; > } > > - err = kvm_init_ipa_range(mmu, type); > + err = kvm_init_ipa_range(kvm, mmu, type); > if (err) > return err; > > @@ -1056,6 +1060,20 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu) > struct kvm_pgtable *pgt = NULL; > > write_lock(&kvm->mmu_lock); > + if (kvm_is_realm(kvm) && > + (kvm_realm_state(kvm) != REALM_STATE_DEAD && > + kvm_realm_state(kvm) != REALM_STATE_NONE)) { > + /* Tearing down RTTs will be added in a later patch */ > + write_unlock(&kvm->mmu_lock); > + > + /* > + * The physical PGD pages are delegated to the RMM, so cannot > + * be freed at this point. This function will be called again > + * from kvm_destroy_realm() after the physical pages have been > + * returned at which point the memory can be freed. > + */ > + return; > + } > pgt = mmu->pgt; > if (pgt) { > mmu->pgd_phys = 0; > diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c > index b88269b80c11..5530ec2653b7 100644 > --- a/arch/arm64/kvm/rme.c > +++ b/arch/arm64/kvm/rme.c > @@ -5,9 +5,20 @@ > > #include > > +#include > +#include > #include > #include > > +#include > + > +static unsigned long rmm_feat_reg0; > + > +static bool rme_supports(unsigned long feature) > +{ > + return !!u64_get_bits(rmm_feat_reg0, feature); > +} > + I don't have strong sense, but the name would be rme_has_feature() since the source is the RMM feature register-0. > static int rmi_check_version(void) > { > struct arm_smccc_res res; > @@ -36,6 +47,285 @@ static int rmi_check_version(void) > return 0; > } > > +u32 kvm_realm_ipa_limit(void) > +{ > + return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_S2SZ); > +} > + > +static int get_start_level(struct realm *realm) > +{ > + return 4 - stage2_pgtable_levels(realm->ia_bits); > +} > + > +static void free_delegated_granule(phys_addr_t phys) > +{ > + if (WARN_ON(rmi_granule_undelegate(phys))) { > + /* Undelegate failed: leak the page */ > + return; > + } > + > + free_page((unsigned long)phys_to_virt(phys)); > +} > + > +static int realm_create_rd(struct kvm *kvm) > +{ > + struct realm *realm = &kvm->arch.realm; > + struct realm_params *params = realm->params; > + void *rd = NULL; > + phys_addr_t rd_phys, params_phys; > + size_t pgd_size = kvm_pgtable_stage2_pgd_size(kvm->arch.mmu.vtcr); > + int i, r; > + > + if (WARN_ON(realm->rd) || WARN_ON(!realm->params)) > + return -EEXIST; > + > + rd = (void *)__get_free_page(GFP_KERNEL); > + if (!rd) > + return -ENOMEM; > + > + rd_phys = virt_to_phys(rd); > + if (rmi_granule_delegate(rd_phys)) { > + r = -ENXIO; > + goto free_rd; > + } > + > + for (i = 0; i < pgd_size; i += PAGE_SIZE) { > + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i; > + > + if (rmi_granule_delegate(pgd_phys)) { > + r = -ENXIO; > + goto out_undelegate_tables; > + } > + } > + The step of 'i' is PAGE_SIZE, inconsistent with what has been done in the tag 'out_undelegate_tables' where the step is expected to be 1. > + realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr); > + > + params->s2sz = VTCR_EL2_IPA(kvm->arch.mmu.vtcr); > + params->rtt_level_start = get_start_level(realm); > + params->rtt_num_start = pgd_size / PAGE_SIZE; > + params->rtt_base = kvm->arch.mmu.pgd_phys; > + params->vmid = realm->vmid; > + > + params_phys = virt_to_phys(params); > + > + if (rmi_realm_create(rd_phys, params_phys)) { > + r = -ENXIO; > + goto out_undelegate_tables; > + } > + > + if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) { > + WARN_ON(rmi_realm_destroy(rd_phys)); > + goto out_undelegate_tables; > + } > + > + realm->rd = rd; > + > + return 0; > + > +out_undelegate_tables: > + while (--i >= 0) { > + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE; > + > + if (WARN_ON(rmi_granule_undelegate(pgd_phys))) { > + /* Leak the pages if they cannot be returned */ > + kvm->arch.mmu.pgt = NULL; > + break; > + } > + } > + if (WARN_ON(rmi_granule_undelegate(rd_phys))) { > + /* Leak the page if it isn't returned */ > + return r; > + } > +free_rd: > + free_page((unsigned long)rd); > + return r; > +} > + > +/* Protects access to rme_vmid_bitmap */ > +static DEFINE_SPINLOCK(rme_vmid_lock); > +static unsigned long *rme_vmid_bitmap; > + > +static int rme_vmid_init(void) > +{ > + unsigned int vmid_count = 1 << kvm_get_vmid_bits(); > + > + rme_vmid_bitmap = bitmap_zalloc(vmid_count, GFP_KERNEL); > + if (!rme_vmid_bitmap) { > + kvm_err("%s: Couldn't allocate rme vmid bitmap\n", __func__); > + return -ENOMEM; > + } > + > + return 0; > +} > + > +static int rme_vmid_reserve(void) > +{ > + int ret; > + unsigned int vmid_count = 1 << kvm_get_vmid_bits(); > + > + spin_lock(&rme_vmid_lock); > + ret = bitmap_find_free_region(rme_vmid_bitmap, vmid_count, 0); > + spin_unlock(&rme_vmid_lock); > + > + return ret; > +} > + > +static void rme_vmid_release(unsigned int vmid) > +{ > + spin_lock(&rme_vmid_lock); > + bitmap_release_region(rme_vmid_bitmap, vmid, 0); > + spin_unlock(&rme_vmid_lock); > +} > + > +static int kvm_create_realm(struct kvm *kvm) > +{ > + struct realm *realm = &kvm->arch.realm; > + int ret; > + > + if (!kvm_is_realm(kvm)) > + return -EINVAL; The duplicated check has been done in kvm_realm_enable_cap(). So it can be dropped safely. > + if (kvm_realm_is_created(kvm)) > + return -EEXIST; > + > + ret = rme_vmid_reserve(); > + if (ret < 0) > + return ret; > + realm->vmid = ret; > + > + ret = realm_create_rd(kvm); > + if (ret) { > + rme_vmid_release(realm->vmid); > + return ret; > + } > + > + WRITE_ONCE(realm->state, REALM_STATE_NEW); > + > + /* The realm is up, free the parameters. */ > + free_page((unsigned long)realm->params); > + realm->params = NULL; > + > + return 0; > +} > + > +static int config_realm_hash_algo(struct realm *realm, > + struct kvm_cap_arm_rme_config_item *cfg) > +{ > + switch (cfg->hash_algo) { > + case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA256: > + if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_256)) > + return -EINVAL; > + break; > + case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA512: > + if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_512)) > + return -EINVAL; > + break; > + default: > + return -EINVAL; > + } > + realm->params->hash_algo = cfg->hash_algo; > + return 0; > +} > + > +static int kvm_rme_config_realm(struct kvm *kvm, struct kvm_enable_cap *cap) > +{ > + struct kvm_cap_arm_rme_config_item cfg; > + struct realm *realm = &kvm->arch.realm; > + int r = 0; > + > + if (kvm_realm_is_created(kvm)) > + return -EBUSY; > + > + if (copy_from_user(&cfg, (void __user *)cap->args[1], sizeof(cfg))) > + return -EFAULT; > + > + switch (cfg.cfg) { > + case KVM_CAP_ARM_RME_CFG_RPV: > + memcpy(&realm->params->rpv, &cfg.rpv, sizeof(cfg.rpv)); > + break; > + case KVM_CAP_ARM_RME_CFG_HASH_ALGO: > + r = config_realm_hash_algo(realm, &cfg); > + break; > + default: > + r = -EINVAL; > + } > + > + return r; > +} > + > +int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap) > +{ > + int r = 0; > + > + if (!kvm_is_realm(kvm)) > + return -EINVAL; > + > + switch (cap->args[0]) { > + case KVM_CAP_ARM_RME_CONFIG_REALM: > + r = kvm_rme_config_realm(kvm, cap); > + break; > + case KVM_CAP_ARM_RME_CREATE_RD: > + r = kvm_create_realm(kvm); > + break; > + default: > + r = -EINVAL; > + break; > + } > + > + return r; > +} > + > +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); > + int i; > + > + if (realm->params) { > + free_page((unsigned long)realm->params); > + realm->params = NULL; > + } > + > + if (!kvm_realm_is_created(kvm)) > + return; > + > + WRITE_ONCE(realm->state, REALM_STATE_DYING); > + > + if (realm->rd) { > + phys_addr_t rd_phys = virt_to_phys(realm->rd); > + > + if (WARN_ON(rmi_realm_destroy(rd_phys))) > + return; > + free_delegated_granule(rd_phys); > + realm->rd = NULL; > + } > + > + rme_vmid_release(realm->vmid); > + > + for (i = 0; i < pgd_size; i += PAGE_SIZE) { > + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i; > + > + if (WARN_ON(rmi_granule_undelegate(pgd_phys))) > + return; > + } > + > + WRITE_ONCE(realm->state, REALM_STATE_DEAD); > + > + /* Now that the Realm is destroyed, free the entry level RTTs */ > + kvm_free_stage2_pgd(&kvm->arch.mmu); > +} > + > +int kvm_init_realm_vm(struct kvm *kvm) > +{ > + struct realm_params *params; > + > + params = (struct realm_params *)get_zeroed_page(GFP_KERNEL); > + if (!params) > + return -ENOMEM; > + > + kvm->arch.realm.params = params; > + return 0; > +} > + > void kvm_init_rme(void) > { > if (PAGE_SIZE != SZ_4K) > @@ -46,5 +336,11 @@ void kvm_init_rme(void) > /* Continue without realm support */ > return; > > + if (WARN_ON(rmi_features(0, &rmm_feat_reg0))) > + return; > + > + if (rme_vmid_init()) > + return; > + > /* Future patch will enable static branch kvm_rme_is_available */ > } Thanks, Gavin