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From: Steven Price <steven.price@arm.com>
To: kvm@vger.kernel.org,
	kvmarm@lists.linux.dev
Cc: Steven Price <steven.price@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	James Morse <james.morse@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Joey Gouly <joey.gouly@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Fuad Tabba <tabba@google.com>,
	linux-coco@lists.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: [PATCH v2 09/43] arm64: RME: ioctls to create and configure realms
Date: Fri, 12 Apr 2024 09:42:35 +0100
Message-Id: <20240412084309.1733783-10-steven.price@arm.com>
In-Reply-To: <20240412084309.1733783-1-steven.price@arm.com>
References: <20240412084056.1733704-1-steven.price@arm.com>
 <20240412084309.1733783-1-steven.price@arm.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Add the KVM_CAP_ARM_RME_CREATE_FD 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.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 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                 |  15 +-
 arch/arm64/kvm/rme.c                 | 282 +++++++++++++++++++++++++++
 5 files changed, 337 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 6f08398537e2..c606316f4729 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -624,6 +624,11 @@ 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 922da3f47227..cf8cc4d30364 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 <uapi/linux/kvm.h>
+
 /**
  * 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;
 };
 
 int 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 2056c660c5ee..5729ea430d6d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -119,6 +119,13 @@ 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:
 		r = -EINVAL;
 		break;
@@ -179,6 +186,13 @@ 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:
@@ -219,6 +233,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kvm_unshare_hyp(kvm, kvm + 1);
 
 	kvm_arm_teardown_hypercalls(kvm);
+	kvm_destroy_realm(kvm);
 }
 
 int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
@@ -328,6 +343,9 @@ 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 18680771cdb0..aae365647b62 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -872,6 +872,10 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
 	struct kvm_pgtable *pgt;
 	u64 mmfr0, mmfr1;
 	u32 phys_shift;
+	u32 ipa_limit = kvm_ipa_limit;
+
+	if (kvm_is_realm(kvm))
+		ipa_limit = kvm_realm_ipa_limit();
 
 	if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
 		return -EINVAL;
@@ -880,12 +884,12 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
 	if (is_protected_kvm_enabled()) {
 		phys_shift = kvm_ipa_limit;
 	} else if (phys_shift) {
-		if (phys_shift > kvm_ipa_limit ||
+		if (phys_shift > ipa_limit ||
 		    phys_shift < ARM64_MIN_PARANGE_BITS)
 			return -EINVAL;
 	} else {
 		phys_shift = KVM_PHYS_SHIFT;
-		if (phys_shift > kvm_ipa_limit) {
+		if (phys_shift > ipa_limit) {
 			pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
 				     current->comm);
 			return -EINVAL;
@@ -1014,6 +1018,13 @@ 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)) {
+		/* TODO: teardown rtts */
+		write_unlock(&kvm->mmu_lock);
+		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 3dbbf9d046bf..658d14e8d87d 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -5,9 +5,20 @@
 
 #include <linux/kvm_host.h>
 
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
 #include <asm/rmi_cmds.h>
 #include <asm/virt.h>
 
+#include <asm/kvm_pgtable.h>
+
+static unsigned long rmm_feat_reg0;
+
+static bool rme_supports(unsigned long feature)
+{
+	return !!u64_get_bits(rmm_feat_reg0, feature);
+}
+
 static int rmi_check_version(void)
 {
 	struct arm_smccc_res res;
@@ -36,8 +47,272 @@ 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 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;
+	struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
+	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 out;
+	}
+
+	for (i = 0; i < pgt->pgd_pages; i++) {
+		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+		if (rmi_granule_delegate(pgd_phys)) {
+			r = -ENXIO;
+			goto out_undelegate_tables;
+		}
+	}
+
+	realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+
+	params->rtt_level_start = get_start_level(realm);
+	params->rtt_num_start = pgt->pgd_pages;
+	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;
+	}
+
+	realm->rd = rd;
+
+	if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) {
+		WARN_ON(rmi_realm_destroy(rd_phys));
+		goto out_undelegate_tables;
+	}
+
+	return 0;
+
+out_undelegate_tables:
+	while (--i >= 0) {
+		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+		WARN_ON(rmi_granule_undelegate(pgd_phys));
+	}
+	WARN_ON(rmi_granule_undelegate(rd_phys));
+out:
+	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) || 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 -EINVAL;
+
+	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;
+	struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
+	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;
+		if (WARN_ON(rmi_granule_undelegate(rd_phys)))
+			return;
+		free_page((unsigned long)realm->rd);
+		realm->rd = NULL;
+	}
+
+	rme_vmid_release(realm->vmid);
+
+	for (i = 0; i < pgt->pgd_pages; i++) {
+		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+		if (WARN_ON(rmi_granule_undelegate(pgd_phys)))
+			return;
+	}
+
+	WRITE_ONCE(realm->state, REALM_STATE_DEAD);
+
+	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;
+
+	/* Default parameters, not exposed to user space */
+	params->s2sz = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+	kvm->arch.realm.params = params;
+	return 0;
+}
+
 int kvm_init_rme(void)
 {
+	int ret;
+
 	if (PAGE_SIZE != SZ_4K)
 		/* Only 4k page size on the host is supported */
 		return 0;
@@ -46,6 +321,13 @@ int kvm_init_rme(void)
 		/* Continue without realm support */
 		return 0;
 
+	if (WARN_ON(rmi_features(0, &rmm_feat_reg0)))
+		return 0;
+
+	ret = rme_vmid_init();
+	if (ret)
+		return ret;
+
 	/* Future patch will enable static branch kvm_rme_is_available */
 
 	return 0;
-- 
2.34.1