[PATCH 06/11] KVM: arm64: CCA: Add basic infrastructure for creating a realm

[Steven Price <steven.price@arm.com>]

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 <steven.price@arm.com>
---
 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 <linux/arm-smccc-rmi.h>
+#include <linux/kvm.h>
+
 /**
  * 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);
 }
 
@@ -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 <linux/arm-rmi-cmds.h>
 #include <linux/kvm_host.h>
 
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
 #include <asm/virt.h>
 
@@ -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;
+	}
+
+	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() &&
-- 
2.43.0