[RFC PATCH 10/28] arm64: RME: Allocate/free RECs to match vCPUs

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

The RMM maintains a data structure known as the Realm Execution Context
(or REC). It is similar to struct kvm_vcpu and tracks the state of the
virtual CPUs. KVM must delegate memory and request the structures are
created when vCPUs are created, and suitably tear down on destruction.

Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/include/asm/kvm_emulate.h |   2 +
 arch/arm64/include/asm/kvm_host.h    |   3 +
 arch/arm64/include/asm/kvm_rme.h     |  10 ++
 arch/arm64/kvm/arm.c                 |   1 +
 arch/arm64/kvm/reset.c               |  11 ++
 arch/arm64/kvm/rme.c                 | 144 +++++++++++++++++++++++++++
 6 files changed, 171 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 5a2b7229e83f..285e62914ca4 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -504,6 +504,8 @@ static inline enum realm_state kvm_realm_state(struct kvm *kvm)
 
 static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu)
 {
+	if (static_branch_unlikely(&kvm_rme_is_available))
+		return vcpu->arch.rec.mpidr != INVALID_HWID;
 	return false;
 }
 
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 04347c3a8c6b..ef497b718cdb 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -505,6 +505,9 @@ struct kvm_vcpu_arch {
 		u64 last_steal;
 		gpa_t base;
 	} steal;
+
+	/* Realm meta data */
+	struct rec rec;
 };
 
 /*
diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index eea5118dfa8a..4b219ebe1400 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -6,6 +6,7 @@
 #ifndef __ASM_KVM_RME_H
 #define __ASM_KVM_RME_H
 
+#include <asm/rmi_smc.h>
 #include <uapi/linux/kvm.h>
 
 enum realm_state {
@@ -29,6 +30,13 @@ struct realm {
 	unsigned int ia_bits;
 };
 
+struct rec {
+	unsigned long mpidr;
+	void *rec_page;
+	struct page *aux_pages[REC_PARAMS_AUX_GRANULES];
+	struct rec_run *run;
+};
+
 int kvm_init_rme(void);
 u32 kvm_realm_ipa_limit(void);
 
@@ -36,6 +44,8 @@ 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);
 void kvm_realm_destroy_rtts(struct realm *realm, u32 ia_bits, u32 start_level);
+int kvm_create_rec(struct kvm_vcpu *vcpu);
+void kvm_destroy_rec(struct kvm_vcpu *vcpu);
 
 #define RME_RTT_BLOCK_LEVEL	2
 #define RME_RTT_MAX_LEVEL	3
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index badd775547b8..52affed2f3cf 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -373,6 +373,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	/* Force users to call KVM_ARM_VCPU_INIT */
 	vcpu->arch.target = -1;
 	bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
+	vcpu->arch.rec.mpidr = INVALID_HWID;
 
 	vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
 
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 9e71d69e051f..0c84392a4bf2 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -135,6 +135,11 @@ int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu, int feature)
 			return -EPERM;
 
 		return kvm_vcpu_finalize_sve(vcpu);
+	case KVM_ARM_VCPU_REC:
+		if (!kvm_is_realm(vcpu->kvm))
+			return -EINVAL;
+
+		return kvm_create_rec(vcpu);
 	}
 
 	return -EINVAL;
@@ -145,6 +150,11 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu)
 	if (vcpu_has_sve(vcpu) && !kvm_arm_vcpu_sve_finalized(vcpu))
 		return false;
 
+	if (kvm_is_realm(vcpu->kvm) &&
+	    !(vcpu_is_rec(vcpu) &&
+	      READ_ONCE(vcpu->kvm->arch.realm.state) == REALM_STATE_ACTIVE))
+		return false;
+
 	return true;
 }
 
@@ -157,6 +167,7 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu)
 	if (sve_state)
 		kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu));
 	kfree(sve_state);
+	kvm_destroy_rec(vcpu);
 }
 
 static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index f7b0e5a779f8..d79ed889ca4d 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -514,6 +514,150 @@ void kvm_destroy_realm(struct kvm *kvm)
 	kvm_free_stage2_pgd(&kvm->arch.mmu);
 }
 
+static void free_rec_aux(struct page **aux_pages,
+			 unsigned int num_aux)
+{
+	unsigned int i;
+
+	for (i = 0; i < num_aux; i++) {
+		phys_addr_t aux_page_phys = page_to_phys(aux_pages[i]);
+
+		if (WARN_ON(rmi_granule_undelegate(aux_page_phys)))
+			continue;
+
+		__free_page(aux_pages[i]);
+	}
+}
+
+static int alloc_rec_aux(struct page **aux_pages,
+			 u64 *aux_phys_pages,
+			 unsigned int num_aux)
+{
+	int ret;
+	unsigned int i;
+
+	for (i = 0; i < num_aux; i++) {
+		struct page *aux_page;
+		phys_addr_t aux_page_phys;
+
+		aux_page = alloc_page(GFP_KERNEL);
+		if (!aux_page) {
+			ret = -ENOMEM;
+			goto out_err;
+		}
+		aux_page_phys = page_to_phys(aux_page);
+		if (rmi_granule_delegate(aux_page_phys)) {
+			__free_page(aux_page);
+			ret = -ENXIO;
+			goto out_err;
+		}
+		aux_pages[i] = aux_page;
+		aux_phys_pages[i] = aux_page_phys;
+	}
+
+	return 0;
+out_err:
+	free_rec_aux(aux_pages, i);
+	return ret;
+}
+
+int kvm_create_rec(struct kvm_vcpu *vcpu)
+{
+	struct user_pt_regs *vcpu_regs = vcpu_gp_regs(vcpu);
+	unsigned long mpidr = kvm_vcpu_get_mpidr_aff(vcpu);
+	struct realm *realm = &vcpu->kvm->arch.realm;
+	struct rec *rec = &vcpu->arch.rec;
+	unsigned long rec_page_phys;
+	struct rec_params *params;
+	int r, i;
+
+	if (kvm_realm_state(vcpu->kvm) != REALM_STATE_NEW)
+		return -ENOENT;
+
+	/*
+	 * The RMM will report PSCI v1.0 to Realms and the KVM_ARM_VCPU_PSCI_0_2
+	 * flag covers v0.2 and onwards.
+	 */
+	if (!test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
+		return -EINVAL;
+
+	BUILD_BUG_ON(sizeof(*params) > PAGE_SIZE);
+	BUILD_BUG_ON(sizeof(*rec->run) > PAGE_SIZE);
+
+	params = (struct rec_params *)get_zeroed_page(GFP_KERNEL);
+	rec->rec_page = (void *)__get_free_page(GFP_KERNEL);
+	rec->run = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!params || !rec->rec_page || !rec->run) {
+		r = -ENOMEM;
+		goto out_free_pages;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(params->gprs); i++)
+		params->gprs[i] = vcpu_regs->regs[i];
+
+	params->pc = vcpu_regs->pc;
+
+	if (vcpu->vcpu_id == 0)
+		params->flags |= REC_PARAMS_FLAG_RUNNABLE;
+
+	rec_page_phys = virt_to_phys(rec->rec_page);
+
+	if (rmi_granule_delegate(rec_page_phys)) {
+		r = -ENXIO;
+		goto out_free_pages;
+	}
+
+	r = alloc_rec_aux(rec->aux_pages, params->aux, realm->num_aux);
+	if (r)
+		goto out_undelegate_rmm_rec;
+
+	params->num_rec_aux = realm->num_aux;
+	params->mpidr = mpidr;
+
+	if (rmi_rec_create(rec_page_phys,
+			   virt_to_phys(realm->rd),
+			   virt_to_phys(params))) {
+		r = -ENXIO;
+		goto out_free_rec_aux;
+	}
+
+	rec->mpidr = mpidr;
+
+	free_page((unsigned long)params);
+	return 0;
+
+out_free_rec_aux:
+	free_rec_aux(rec->aux_pages, realm->num_aux);
+out_undelegate_rmm_rec:
+	if (WARN_ON(rmi_granule_undelegate(rec_page_phys)))
+		rec->rec_page = NULL;
+out_free_pages:
+	free_page((unsigned long)rec->run);
+	free_page((unsigned long)rec->rec_page);
+	free_page((unsigned long)params);
+	return r;
+}
+
+void kvm_destroy_rec(struct kvm_vcpu *vcpu)
+{
+	struct realm *realm = &vcpu->kvm->arch.realm;
+	struct rec *rec = &vcpu->arch.rec;
+	unsigned long rec_page_phys;
+
+	if (!vcpu_is_rec(vcpu))
+		return;
+
+	rec_page_phys = virt_to_phys(rec->rec_page);
+
+	if (WARN_ON(rmi_rec_destroy(rec_page_phys)))
+		return;
+	if (WARN_ON(rmi_granule_undelegate(rec_page_phys)))
+		return;
+
+	free_rec_aux(rec->aux_pages, realm->num_aux);
+	free_page((unsigned long)rec->rec_page);
+}
+
 int kvm_init_realm_vm(struct kvm *kvm)
 {
 	struct realm_params *params;
-- 
2.34.1