From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F149684D02; Tue, 29 Apr 2025 09:45:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745919961; cv=none; b=iy0tiPe6W5GPcA9h19ZCRAOX9pANvrLJVU58ZfV07sxu3de4YePy4esYh8nYBs6BNw6AuOSvK2U+lbDQidxlCq2cfGiE5SE68gdifK1vYMw1BdybZ2Ij8NocSBnDe4uZfe+8i4LdonqutJ/Hk9S8yItDGivOsW4SrPGGAqlfRyE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745919961; c=relaxed/simple; bh=X0VXGSMHf//qV5FNiM4OS+QMOL5TZTK4cwEyGS+j43k=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oGZNkigsOE3jYx5qtVHT42ShEGyshEn1ufag9cvCFM58NddxktKq4XHE7Wsulou3kDh4jAx29DOSs9mXYl6+zXGvMqZ0lIVw72D1vH/L3iJE+yt1pzgCGtVykL00oGIbnepEQkk5uWEKDNUVleoeLC5NToQYKwYbU4nEjstVSV4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 663011515; Tue, 29 Apr 2025 02:45:51 -0700 (PDT) Received: from [10.1.33.43] (unknown [10.1.33.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E83133F673; Tue, 29 Apr 2025 02:45:54 -0700 (PDT) Message-ID: Date: Tue, 29 Apr 2025 10:45:54 +0100 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 07/43] arm64: RME: ioctls to create and configure realms Content-Language: en-GB To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , 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 , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20250416134208.383984-1-steven.price@arm.com> <20250416134208.383984-8-steven.price@arm.com> From: Suzuki K Poulose In-Reply-To: <20250416134208.383984-8-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 16/04/2025 14:41, 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 > Reviewed-by: Gavin Shan > --- > 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 | 5 + > arch/arm64/include/asm/kvm_rme.h | 19 ++ > arch/arm64/kvm/arm.c | 16 ++ > arch/arm64/kvm/mmu.c | 22 +- > arch/arm64/kvm/rme.c | 319 +++++++++++++++++++++++++++ > 5 files changed, 379 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > index 1c43a4fc25dd..4ee6c215da82 100644 > --- a/arch/arm64/include/asm/kvm_emulate.h > +++ b/arch/arm64/include/asm/kvm_emulate.h > @@ -699,6 +699,11 @@ 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 9c8a0b23e0e4..5dc1915de891 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 /* __ASM_KVM_RME_H */ > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 856a721d41ac..0e8482fdc4d3 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -136,6 +136,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, > } > mutex_unlock(&kvm->lock); > break; > + case KVM_CAP_ARM_RME: > + mutex_lock(&kvm->lock); > + r = kvm_realm_enable_cap(kvm, cap); > + mutex_unlock(&kvm->lock); > + break; > default: > break; > } > @@ -198,6 +203,13 @@ 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: > @@ -257,6 +269,7 @@ 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) > @@ -405,6 +418,9 @@ 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 2feb6c6b63af..5957a07de86d 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -876,12 +876,16 @@ 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; > > @@ -946,7 +950,7 @@ 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; > > @@ -1072,6 +1076,20 @@ 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 67cf2d94cb2d..dbb6521fe380 100644 > --- a/arch/arm64/kvm/rme.c > +++ b/arch/arm64/kvm/rme.c > @@ -5,9 +5,23 @@ > > #include > > +#include > +#include > #include > #include > > +#include > + > +static unsigned long rmm_feat_reg0; > + > +#define RMM_PAGE_SHIFT 12 > +#define RMM_PAGE_SIZE BIT(RMM_PAGE_SHIFT) > + > +static bool rme_has_feature(unsigned long feature) > +{ > + return !!u64_get_bits(rmm_feat_reg0, feature); > +} > + > static int rmi_check_version(void) > { > struct arm_smccc_res res; > @@ -42,6 +56,305 @@ 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 - ((realm->ia_bits - 8) / (RMM_PAGE_SHIFT - 3)); minor nit: It may be worth adding a comment here, how we got this magic number 8. We could say: Open coded version of ARM64_HW_PGTABLE_LEVELS(ia_bits - 4) (accounting for the concatenation of upto 16 tables in entry level) for RMM Stage2. > +} > + > +static void free_delegated_granule(phys_addr_t phys) > +{ > + if (WARN_ON(rmi_granule_undelegate(phys))) { > + /* Undelegate failed: leak the page */ > + return; > + } > + > + kvm_account_pgtable_pages(phys_to_virt(phys), -1); > + > + free_page((unsigned long)phys_to_virt(phys)); > +} > + > +/* Calculate the number of s2 root rtts needed */ > +static int realm_num_root_rtts(struct realm *realm) > +{ > + unsigned int ipa_bits = realm->ia_bits; > + unsigned int levels = 3 - get_start_level(realm); nit: Why is this 3 - start_level and not 4 ? Though that is compensated by the "levels + 1" below, hence the calculation is correct. > + unsigned int sl_ipa_bits = (levels + 1) * (RMM_PAGE_SHIFT - 3) + > + RMM_PAGE_SHIFT; > + > + if (sl_ipa_bits >= ipa_bits) > + return 1; > + > + return 1 << (ipa_bits - sl_ipa_bits); > +} > + > +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; > + int rtt_num_start; > + > + realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr); > + rtt_num_start = realm_num_root_rtts(realm); > + > + if (WARN_ON(realm->rd || !realm->params)) > + return -EEXIST; > + > + if (pgd_size / RMM_PAGE_SIZE < rtt_num_start) > + return -EINVAL; > + > + 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 += RMM_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; > + } > + } > + > + params->s2sz = VTCR_EL2_IPA(kvm->arch.mmu.vtcr); > + params->rtt_level_start = get_start_level(realm); > + params->rtt_num_start = rtt_num_start; > + 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) { > + i -= RMM_PAGE_SIZE; > + > + phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i; > + > + if (WARN_ON(rmi_granule_undelegate(pgd_phys))) { > + /* Leak the pages if they cannot be returned */ > + kvm->arch.mmu.pgt = NULL; > + break; > + } minor nit: Do we need to try undelegating the other pages ? We could make that WARN_ON_ONCE() too. Suzuki