// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2021 Google LLC
 * Author: Fuad Tabba <tabba@google.com>
 */

#include <linux/kvm_host.h>
#include <linux/mm.h>

#include <asm/kvm_emulate.h>

#include <nvhe/mem_protect.h>
#include <nvhe/memory.h>
#include <nvhe/pkvm.h>
#include <nvhe/trap_handler.h>

/* Used by icache_is_aliasing(). */
unsigned long __icache_flags;

/* Used by kvm_get_vttbr(). */
unsigned int kvm_arm_vmid_bits;

unsigned int kvm_host_sve_max_vl;

/*
 * The currently loaded hyp vCPU for each physical CPU. Used in protected mode
 * for both protected and non-protected VMs.
 */
static DEFINE_PER_CPU(struct pkvm_hyp_vcpu *, loaded_hyp_vcpu);

static void pkvm_vcpu_reset_hcr(struct kvm_vcpu *vcpu)
{
        vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;

        if (has_hvhe())
                vcpu->arch.hcr_el2 |= HCR_E2H;

        if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) {
                /* route synchronous external abort exceptions to EL2 */
                vcpu->arch.hcr_el2 |= HCR_TEA;
                /* trap error record accesses */
                vcpu->arch.hcr_el2 |= HCR_TERR;
        }

        if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
                vcpu->arch.hcr_el2 |= HCR_FWB;

        if (cpus_have_final_cap(ARM64_HAS_EVT) &&
            !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE) &&
            kvm_read_vm_id_reg(vcpu->kvm, SYS_CTR_EL0) == read_cpuid(CTR_EL0))
                vcpu->arch.hcr_el2 |= HCR_TID4;
        else
                vcpu->arch.hcr_el2 |= HCR_TID2;

        if (vcpu_has_ptrauth(vcpu))
                vcpu->arch.hcr_el2 |= (HCR_API | HCR_APK);

        if (kvm_has_mte(vcpu->kvm))
                vcpu->arch.hcr_el2 |= HCR_ATA;
}

static void pvm_init_traps_hcr(struct kvm_vcpu *vcpu)
{
        struct kvm *kvm = vcpu->kvm;
        u64 val = vcpu->arch.hcr_el2;

        /* No support for AArch32. */
        val |= HCR_RW;

        /*
         * Always trap:
         * - Feature id registers: to control features exposed to guests
         * - Implementation-defined features
         */
        val |= HCR_TACR | HCR_TIDCP | HCR_TID3 | HCR_TID1;

        if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, RAS, IMP)) {
                val |= HCR_TERR | HCR_TEA;
                val &= ~(HCR_FIEN);
        }

        if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, AMU, IMP))
                val &= ~(HCR_AMVOFFEN);

        if (!kvm_has_mte(kvm)) {
                val |= HCR_TID5;
                val &= ~(HCR_DCT | HCR_ATA);
        }

        if (!kvm_has_feat(kvm, ID_AA64MMFR1_EL1, LO, IMP))
                val |= HCR_TLOR;

        vcpu->arch.hcr_el2 = val;
}

static void pvm_init_traps_mdcr(struct kvm_vcpu *vcpu)
{
        struct kvm *kvm = vcpu->kvm;
        u64 val = vcpu->arch.mdcr_el2;

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, PMUVer, IMP)) {
                val |= MDCR_EL2_TPM | MDCR_EL2_TPMCR;
                val &= ~(MDCR_EL2_HPME | MDCR_EL2_MTPME | MDCR_EL2_HPMN_MASK);
        }

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, DebugVer, IMP))
                val |= MDCR_EL2_TDRA | MDCR_EL2_TDA;

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, DoubleLock, IMP))
                val |= MDCR_EL2_TDOSA;

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, PMSVer, IMP)) {
                val |= MDCR_EL2_TPMS;
                val &= ~MDCR_EL2_E2PB_MASK;
        }

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceFilt, IMP))
                val |= MDCR_EL2_TTRF;

        if (!kvm_has_feat(kvm, ID_AA64DFR0_EL1, TraceBuffer, IMP))
                val &= ~MDCR_EL2_E2TB_MASK;

        /* Trap Debug Communications Channel registers */
        if (!kvm_has_feat(kvm, ID_AA64MMFR0_EL1, FGT, IMP))
                val |= MDCR_EL2_TDCC;

        vcpu->arch.mdcr_el2 = val;
}

/*
 * Check that cpu features that are neither trapped nor supported are not
 * enabled for protected VMs.
 */
static int pkvm_check_pvm_cpu_features(struct kvm_vcpu *vcpu)
{
        struct kvm *kvm = vcpu->kvm;

        /* No AArch32 support for protected guests. */
        if (kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL0, AARCH32) ||
            kvm_has_feat(kvm, ID_AA64PFR0_EL1, EL1, AARCH32))
                return -EINVAL;

        /*
         * Linux guests assume support for floating-point and Advanced SIMD. Do
         * not change the trapping behavior for these from the KVM default.
         */
        if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, FP, IMP) ||
            !kvm_has_feat(kvm, ID_AA64PFR0_EL1, AdvSIMD, IMP))
                return -EINVAL;

        /* No SME support in KVM right now. Check to catch if it changes. */
        if (kvm_has_feat(kvm, ID_AA64PFR1_EL1, SME, IMP))
                return -EINVAL;

        return 0;
}

/*
 * Initialize trap register values in protected mode.
 */
static int pkvm_vcpu_init_traps(struct pkvm_hyp_vcpu *hyp_vcpu)
{
        struct kvm_vcpu *vcpu = &hyp_vcpu->vcpu;
        int ret;

        vcpu->arch.mdcr_el2 = 0;

        pkvm_vcpu_reset_hcr(vcpu);

        if ((!pkvm_hyp_vcpu_is_protected(hyp_vcpu))) {
                struct kvm_vcpu *host_vcpu = hyp_vcpu->host_vcpu;

                /* Trust the host for non-protected vcpu features. */
                vcpu->arch.hcrx_el2 = host_vcpu->arch.hcrx_el2;
                return 0;
        }

        ret = pkvm_check_pvm_cpu_features(vcpu);
        if (ret)
                return ret;

        pvm_init_traps_hcr(vcpu);
        pvm_init_traps_mdcr(vcpu);
        vcpu_set_hcrx(vcpu);

        return 0;
}

/*
 * Start the VM table handle at the offset defined instead of at 0.
 * Mainly for sanity checking and debugging.
 */
#define HANDLE_OFFSET 0x1000

/*
 * Marks a reserved but not yet used entry in the VM table.
 */
#define RESERVED_ENTRY ((void *)0xa110ca7ed)

static unsigned int vm_handle_to_idx(pkvm_handle_t handle)
{
        return handle - HANDLE_OFFSET;
}

static pkvm_handle_t idx_to_vm_handle(unsigned int idx)
{
        return idx + HANDLE_OFFSET;
}

/*
 * Spinlock for protecting state related to the VM table. Protects writes
 * to 'vm_table', 'nr_table_entries', and other per-vm state on initialization.
 * Also protects reads and writes to 'last_hyp_vcpu_lookup'.
 */
DEFINE_HYP_SPINLOCK(vm_table_lock);

/*
 * A table that tracks all VMs in protected mode.
 * Allocated during hyp initialization and setup.
 */
static struct pkvm_hyp_vm **vm_table;

void pkvm_hyp_vm_table_init(void *tbl)
{
        WARN_ON(vm_table);
        vm_table = tbl;
}

/*
 * Return the hyp vm structure corresponding to the handle.
 */
static struct pkvm_hyp_vm *get_vm_by_handle(pkvm_handle_t handle)
{
        unsigned int idx = vm_handle_to_idx(handle);

        if (unlikely(idx >= KVM_MAX_PVMS))
                return NULL;

        /* A reserved entry doesn't represent an initialized VM. */
        if (unlikely(vm_table[idx] == RESERVED_ENTRY))
                return NULL;

        return vm_table[idx];
}

struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
                                         unsigned int vcpu_idx)
{
        struct pkvm_hyp_vcpu *hyp_vcpu = NULL;
        struct pkvm_hyp_vm *hyp_vm;

        /* Cannot load a new vcpu without putting the old one first. */
        if (__this_cpu_read(loaded_hyp_vcpu))
                return NULL;

        hyp_spin_lock(&vm_table_lock);
        hyp_vm = get_vm_by_handle(handle);
        if (!hyp_vm || hyp_vm->kvm.created_vcpus <= vcpu_idx)
                goto unlock;

        hyp_vcpu = hyp_vm->vcpus[vcpu_idx];
        if (!hyp_vcpu)
                goto unlock;

        /* Ensure vcpu isn't loaded on more than one cpu simultaneously. */
        if (unlikely(hyp_vcpu->loaded_hyp_vcpu)) {
                hyp_vcpu = NULL;
                goto unlock;
        }

        hyp_vcpu->loaded_hyp_vcpu = this_cpu_ptr(&loaded_hyp_vcpu);
        hyp_page_ref_inc(hyp_virt_to_page(hyp_vm));
unlock:
        hyp_spin_unlock(&vm_table_lock);

        if (hyp_vcpu)
                __this_cpu_write(loaded_hyp_vcpu, hyp_vcpu);
        return hyp_vcpu;
}

void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
{
        struct pkvm_hyp_vm *hyp_vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu);

        hyp_spin_lock(&vm_table_lock);
        hyp_vcpu->loaded_hyp_vcpu = NULL;
        __this_cpu_write(loaded_hyp_vcpu, NULL);
        hyp_page_ref_dec(hyp_virt_to_page(hyp_vm));
        hyp_spin_unlock(&vm_table_lock);
}

struct pkvm_hyp_vcpu *pkvm_get_loaded_hyp_vcpu(void)
{
        return __this_cpu_read(loaded_hyp_vcpu);

}

struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle)
{
        struct pkvm_hyp_vm *hyp_vm;

        hyp_spin_lock(&vm_table_lock);
        hyp_vm = get_vm_by_handle(handle);
        if (hyp_vm)
                hyp_page_ref_inc(hyp_virt_to_page(hyp_vm));
        hyp_spin_unlock(&vm_table_lock);

        return hyp_vm;
}

void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm)
{
        hyp_spin_lock(&vm_table_lock);
        hyp_page_ref_dec(hyp_virt_to_page(hyp_vm));
        hyp_spin_unlock(&vm_table_lock);
}

struct pkvm_hyp_vm *get_np_pkvm_hyp_vm(pkvm_handle_t handle)
{
        struct pkvm_hyp_vm *hyp_vm = get_pkvm_hyp_vm(handle);

        if (hyp_vm && pkvm_hyp_vm_is_protected(hyp_vm)) {
                put_pkvm_hyp_vm(hyp_vm);
                hyp_vm = NULL;
        }

        return hyp_vm;
}

static void pkvm_init_features_from_host(struct pkvm_hyp_vm *hyp_vm, const struct kvm *host_kvm)
{
        struct kvm *kvm = &hyp_vm->kvm;
        unsigned long host_arch_flags = READ_ONCE(host_kvm->arch.flags);
        DECLARE_BITMAP(allowed_features, KVM_VCPU_MAX_FEATURES);

        /* CTR_EL0 is always under host control, even for protected VMs. */
        hyp_vm->kvm.arch.ctr_el0 = host_kvm->arch.ctr_el0;

        /* Preserve the vgic model so that GICv3 emulation works */
        hyp_vm->kvm.arch.vgic.vgic_model = host_kvm->arch.vgic.vgic_model;

        /* No restrictions for non-protected VMs. */
        if (!kvm_vm_is_protected(kvm)) {
                hyp_vm->kvm.arch.flags = host_arch_flags;
                hyp_vm->kvm.arch.flags &= ~BIT_ULL(KVM_ARCH_FLAG_ID_REGS_INITIALIZED);

                bitmap_copy(kvm->arch.vcpu_features,
                            host_kvm->arch.vcpu_features,
                            KVM_VCPU_MAX_FEATURES);

                if (test_bit(KVM_ARCH_FLAG_WRITABLE_IMP_ID_REGS, &host_arch_flags))
                        hyp_vm->kvm.arch.midr_el1 = host_kvm->arch.midr_el1;

                return;
        }

        if (kvm_pkvm_ext_allowed(kvm, KVM_CAP_ARM_MTE))
                kvm->arch.flags |= host_arch_flags & BIT(KVM_ARCH_FLAG_MTE_ENABLED);

        bitmap_zero(allowed_features, KVM_VCPU_MAX_FEATURES);

        set_bit(KVM_ARM_VCPU_PSCI_0_2, allowed_features);

        if (kvm_pkvm_ext_allowed(kvm, KVM_CAP_ARM_PMU_V3))
                set_bit(KVM_ARM_VCPU_PMU_V3, allowed_features);

        if (kvm_pkvm_ext_allowed(kvm, KVM_CAP_ARM_PTRAUTH_ADDRESS))
                set_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, allowed_features);

        if (kvm_pkvm_ext_allowed(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC))
                set_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, allowed_features);

        if (kvm_pkvm_ext_allowed(kvm, KVM_CAP_ARM_SVE)) {
                set_bit(KVM_ARM_VCPU_SVE, allowed_features);
                kvm->arch.flags |= host_arch_flags & BIT(KVM_ARCH_FLAG_GUEST_HAS_SVE);
        }

        bitmap_and(kvm->arch.vcpu_features, host_kvm->arch.vcpu_features,
                   allowed_features, KVM_VCPU_MAX_FEATURES);
}

static void unpin_host_vcpu(struct kvm_vcpu *host_vcpu)
{
        if (host_vcpu)
                hyp_unpin_shared_mem(host_vcpu, host_vcpu + 1);
}

static void unpin_host_sve_state(struct pkvm_hyp_vcpu *hyp_vcpu)
{
        void *sve_state;

        if (!vcpu_has_feature(&hyp_vcpu->vcpu, KVM_ARM_VCPU_SVE))
                return;

        sve_state = hyp_vcpu->vcpu.arch.sve_state;
        hyp_unpin_shared_mem(sve_state,
                             sve_state + vcpu_sve_state_size(&hyp_vcpu->vcpu));
}

static void unpin_host_vcpus(struct pkvm_hyp_vcpu *hyp_vcpus[],
                             unsigned int nr_vcpus)
{
        int i;

        for (i = 0; i < nr_vcpus; i++) {
                struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vcpus[i];

                if (!hyp_vcpu)
                        continue;

                unpin_host_vcpu(hyp_vcpu->host_vcpu);
                unpin_host_sve_state(hyp_vcpu);
        }
}

static void init_pkvm_hyp_vm(struct kvm *host_kvm, struct pkvm_hyp_vm *hyp_vm,
                             unsigned int nr_vcpus, pkvm_handle_t handle)
{
        struct kvm_s2_mmu *mmu = &hyp_vm->kvm.arch.mmu;
        int idx = vm_handle_to_idx(handle);

        hyp_vm->kvm.arch.pkvm.handle = handle;

        hyp_vm->host_kvm = host_kvm;
        hyp_vm->kvm.created_vcpus = nr_vcpus;
        hyp_vm->kvm.arch.pkvm.is_protected = READ_ONCE(host_kvm->arch.pkvm.is_protected);
        hyp_vm->kvm.arch.pkvm.is_created = true;
        hyp_vm->kvm.arch.flags = 0;
        pkvm_init_features_from_host(hyp_vm, host_kvm);

        /* VMID 0 is reserved for the host */
        atomic64_set(&mmu->vmid.id, idx + 1);

        mmu->vtcr = host_mmu.arch.mmu.vtcr;
        mmu->arch = &hyp_vm->kvm.arch;
        mmu->pgt = &hyp_vm->pgt;
}

static int pkvm_vcpu_init_sve(struct pkvm_hyp_vcpu *hyp_vcpu, struct kvm_vcpu *host_vcpu)
{
        struct kvm_vcpu *vcpu = &hyp_vcpu->vcpu;
        unsigned int sve_max_vl;
        size_t sve_state_size;
        void *sve_state;
        int ret = 0;

        if (!vcpu_has_feature(vcpu, KVM_ARM_VCPU_SVE)) {
                vcpu_clear_flag(vcpu, VCPU_SVE_FINALIZED);
                return 0;
        }

        /* Limit guest vector length to the maximum supported by the host. */
        sve_max_vl = min(READ_ONCE(host_vcpu->arch.sve_max_vl), kvm_host_sve_max_vl);
        sve_state_size = sve_state_size_from_vl(sve_max_vl);
        sve_state = kern_hyp_va(READ_ONCE(host_vcpu->arch.sve_state));

        if (!sve_state || !sve_state_size) {
                ret = -EINVAL;
                goto err;
        }

        ret = hyp_pin_shared_mem(sve_state, sve_state + sve_state_size);
        if (ret)
                goto err;

        vcpu->arch.sve_state = sve_state;
        vcpu->arch.sve_max_vl = sve_max_vl;

        return 0;
err:
        clear_bit(KVM_ARM_VCPU_SVE, vcpu->kvm->arch.vcpu_features);
        return ret;
}

static int vm_copy_id_regs(struct pkvm_hyp_vcpu *hyp_vcpu)
{
        struct pkvm_hyp_vm *hyp_vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu);
        const struct kvm *host_kvm = hyp_vm->host_kvm;
        struct kvm *kvm = &hyp_vm->kvm;

        if (!test_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &host_kvm->arch.flags))
                return -EINVAL;

        if (test_and_set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags))
                return 0;

        memcpy(kvm->arch.id_regs, host_kvm->arch.id_regs, sizeof(kvm->arch.id_regs));

        return 0;
}

static int pkvm_vcpu_init_sysregs(struct pkvm_hyp_vcpu *hyp_vcpu)
{
        int ret = 0;

        if (pkvm_hyp_vcpu_is_protected(hyp_vcpu))
                kvm_init_pvm_id_regs(&hyp_vcpu->vcpu);
        else
                ret = vm_copy_id_regs(hyp_vcpu);

        return ret;
}

static int init_pkvm_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu,
                              struct pkvm_hyp_vm *hyp_vm,
                              struct kvm_vcpu *host_vcpu)
{
        int ret = 0;

        if (hyp_pin_shared_mem(host_vcpu, host_vcpu + 1))
                return -EBUSY;

        hyp_vcpu->host_vcpu = host_vcpu;

        hyp_vcpu->vcpu.kvm = &hyp_vm->kvm;
        hyp_vcpu->vcpu.vcpu_id = READ_ONCE(host_vcpu->vcpu_id);
        hyp_vcpu->vcpu.vcpu_idx = READ_ONCE(host_vcpu->vcpu_idx);

        hyp_vcpu->vcpu.arch.hw_mmu = &hyp_vm->kvm.arch.mmu;
        hyp_vcpu->vcpu.arch.cflags = READ_ONCE(host_vcpu->arch.cflags);
        hyp_vcpu->vcpu.arch.mp_state.mp_state = KVM_MP_STATE_STOPPED;

        ret = pkvm_vcpu_init_sysregs(hyp_vcpu);
        if (ret)
                goto done;

        ret = pkvm_vcpu_init_traps(hyp_vcpu);
        if (ret)
                goto done;

        ret = pkvm_vcpu_init_sve(hyp_vcpu, host_vcpu);
done:
        if (ret)
                unpin_host_vcpu(host_vcpu);
        return ret;
}

static int find_free_vm_table_entry(void)
{
        int i;

        for (i = 0; i < KVM_MAX_PVMS; ++i) {
                if (!vm_table[i])
                        return i;
        }

        return -ENOMEM;
}

/*
 * Reserve a VM table entry.
 *
 * Return a unique handle to the VM on success,
 * negative error code on failure.
 */
static int allocate_vm_table_entry(void)
{
        int idx;

        hyp_assert_lock_held(&vm_table_lock);

        /*
         * Initializing protected state might have failed, yet a malicious
         * host could trigger this function. Thus, ensure that 'vm_table'
         * exists.
         */
        if (unlikely(!vm_table))
                return -EINVAL;

        idx = find_free_vm_table_entry();
        if (unlikely(idx < 0))
                return idx;

        vm_table[idx] = RESERVED_ENTRY;

        return idx;
}

static int __insert_vm_table_entry(pkvm_handle_t handle,
                                   struct pkvm_hyp_vm *hyp_vm)
{
        unsigned int idx;

        hyp_assert_lock_held(&vm_table_lock);

        /*
         * Initializing protected state might have failed, yet a malicious
         * host could trigger this function. Thus, ensure that 'vm_table'
         * exists.
         */
        if (unlikely(!vm_table))
                return -EINVAL;

        idx = vm_handle_to_idx(handle);
        if (unlikely(idx >= KVM_MAX_PVMS))
                return -EINVAL;

        if (unlikely(vm_table[idx] != RESERVED_ENTRY))
                return -EINVAL;

        vm_table[idx] = hyp_vm;

        return 0;
}

/*
 * Insert a pointer to the initialized VM into the VM table.
 *
 * Return 0 on success, or negative error code on failure.
 */
static int insert_vm_table_entry(pkvm_handle_t handle,
                                 struct pkvm_hyp_vm *hyp_vm)
{
        int ret;

        hyp_spin_lock(&vm_table_lock);
        ret = __insert_vm_table_entry(handle, hyp_vm);
        hyp_spin_unlock(&vm_table_lock);

        return ret;
}

/*
 * Deallocate and remove the VM table entry corresponding to the handle.
 */
static void remove_vm_table_entry(pkvm_handle_t handle)
{
        hyp_assert_lock_held(&vm_table_lock);
        vm_table[vm_handle_to_idx(handle)] = NULL;
}

static size_t pkvm_get_hyp_vm_size(unsigned int nr_vcpus)
{
        return size_add(sizeof(struct pkvm_hyp_vm),
                size_mul(sizeof(struct pkvm_hyp_vcpu *), nr_vcpus));
}

static void *map_donated_memory_noclear(unsigned long host_va, size_t size)
{
        void *va = (void *)kern_hyp_va(host_va);

        if (!PAGE_ALIGNED(va))
                return NULL;

        if (__pkvm_host_donate_hyp(hyp_virt_to_pfn(va),
                                   PAGE_ALIGN(size) >> PAGE_SHIFT))
                return NULL;

        return va;
}

static void *map_donated_memory(unsigned long host_va, size_t size)
{
        void *va = map_donated_memory_noclear(host_va, size);

        if (va)
                memset(va, 0, size);

        return va;
}

static void __unmap_donated_memory(void *va, size_t size)
{
        kvm_flush_dcache_to_poc(va, size);
        WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(va),
                                       PAGE_ALIGN(size) >> PAGE_SHIFT));
}

static void unmap_donated_memory(void *va, size_t size)
{
        if (!va)
                return;

        memset(va, 0, size);
        __unmap_donated_memory(va, size);
}

static void unmap_donated_memory_noclear(void *va, size_t size)
{
        if (!va)
                return;

        __unmap_donated_memory(va, size);
}

/*
 * Reserves an entry in the hypervisor for a new VM in protected mode.
 *
 * Return a unique handle to the VM on success, negative error code on failure.
 */
int __pkvm_reserve_vm(void)
{
        int ret;

        hyp_spin_lock(&vm_table_lock);
        ret = allocate_vm_table_entry();
        hyp_spin_unlock(&vm_table_lock);

        if (ret < 0)
                return ret;

        return idx_to_vm_handle(ret);
}

/*
 * Removes a reserved entry, but only if is hasn't been used yet.
 * Otherwise, the VM needs to be destroyed.
 */
void __pkvm_unreserve_vm(pkvm_handle_t handle)
{
        unsigned int idx = vm_handle_to_idx(handle);

        if (unlikely(!vm_table))
                return;

        hyp_spin_lock(&vm_table_lock);
        if (likely(idx < KVM_MAX_PVMS && vm_table[idx] == RESERVED_ENTRY))
                remove_vm_table_entry(handle);
        hyp_spin_unlock(&vm_table_lock);
}

/*
 * Initialize the hypervisor copy of the VM state using host-donated memory.
 *
 * Unmap the donated memory from the host at stage 2.
 *
 * host_kvm: A pointer to the host's struct kvm.
 * vm_hva: The host va of the area being donated for the VM state.
 *         Must be page aligned.
 * pgd_hva: The host va of the area being donated for the stage-2 PGD for
 *          the VM. Must be page aligned. Its size is implied by the VM's
 *          VTCR.
 *
 * Return 0 success, negative error code on failure.
 */
int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
                   unsigned long pgd_hva)
{
        struct pkvm_hyp_vm *hyp_vm = NULL;
        size_t vm_size, pgd_size;
        unsigned int nr_vcpus;
        pkvm_handle_t handle;
        void *pgd = NULL;
        int ret;

        ret = hyp_pin_shared_mem(host_kvm, host_kvm + 1);
        if (ret)
                return ret;

        nr_vcpus = READ_ONCE(host_kvm->created_vcpus);
        if (nr_vcpus < 1) {
                ret = -EINVAL;
                goto err_unpin_kvm;
        }

        handle = READ_ONCE(host_kvm->arch.pkvm.handle);
        if (unlikely(handle < HANDLE_OFFSET)) {
                ret = -EINVAL;
                goto err_unpin_kvm;
        }

        vm_size = pkvm_get_hyp_vm_size(nr_vcpus);
        pgd_size = kvm_pgtable_stage2_pgd_size(host_mmu.arch.mmu.vtcr);

        ret = -ENOMEM;

        hyp_vm = map_donated_memory(vm_hva, vm_size);
        if (!hyp_vm)
                goto err_remove_mappings;

        pgd = map_donated_memory_noclear(pgd_hva, pgd_size);
        if (!pgd)
                goto err_remove_mappings;

        init_pkvm_hyp_vm(host_kvm, hyp_vm, nr_vcpus, handle);

        ret = kvm_guest_prepare_stage2(hyp_vm, pgd);
        if (ret)
                goto err_remove_mappings;

        /* Must be called last since this publishes the VM. */
        ret = insert_vm_table_entry(handle, hyp_vm);
        if (ret)
                goto err_remove_mappings;

        return 0;

err_remove_mappings:
        unmap_donated_memory(hyp_vm, vm_size);
        unmap_donated_memory(pgd, pgd_size);
err_unpin_kvm:
        hyp_unpin_shared_mem(host_kvm, host_kvm + 1);
        return ret;
}

/*
 * Initialize the hypervisor copy of the vCPU state using host-donated memory.
 *
 * handle: The hypervisor handle for the vm.
 * host_vcpu: A pointer to the corresponding host vcpu.
 * vcpu_hva: The host va of the area being donated for the vcpu state.
 *           Must be page aligned. The size of the area must be equal to
 *           the page-aligned size of 'struct pkvm_hyp_vcpu'.
 * Return 0 on success, negative error code on failure.
 */
int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
                     unsigned long vcpu_hva)
{
        struct pkvm_hyp_vcpu *hyp_vcpu;
        struct pkvm_hyp_vm *hyp_vm;
        unsigned int idx;
        int ret;

        hyp_vcpu = map_donated_memory(vcpu_hva, sizeof(*hyp_vcpu));
        if (!hyp_vcpu)
                return -ENOMEM;

        hyp_spin_lock(&vm_table_lock);

        hyp_vm = get_vm_by_handle(handle);
        if (!hyp_vm) {
                ret = -ENOENT;
                goto unlock;
        }

        ret = init_pkvm_hyp_vcpu(hyp_vcpu, hyp_vm, host_vcpu);
        if (ret)
                goto unlock;

        idx = hyp_vcpu->vcpu.vcpu_idx;
        if (idx >= hyp_vm->kvm.created_vcpus) {
                ret = -EINVAL;
                goto unlock;
        }

        if (hyp_vm->vcpus[idx]) {
                ret = -EINVAL;
                goto unlock;
        }

        hyp_vm->vcpus[idx] = hyp_vcpu;
unlock:
        hyp_spin_unlock(&vm_table_lock);

        if (ret)
                unmap_donated_memory(hyp_vcpu, sizeof(*hyp_vcpu));
        return ret;
}

static void
teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size)
{
        size = PAGE_ALIGN(size);
        memset(addr, 0, size);

        for (void *start = addr; start < addr + size; start += PAGE_SIZE)
                push_hyp_memcache(mc, start, hyp_virt_to_phys);

        unmap_donated_memory_noclear(addr, size);
}

int __pkvm_teardown_vm(pkvm_handle_t handle)
{
        struct kvm_hyp_memcache *mc, *stage2_mc;
        struct pkvm_hyp_vm *hyp_vm;
        struct kvm *host_kvm;
        unsigned int idx;
        size_t vm_size;
        int err;

        hyp_spin_lock(&vm_table_lock);
        hyp_vm = get_vm_by_handle(handle);
        if (!hyp_vm) {
                err = -ENOENT;
                goto err_unlock;
        }

        if (WARN_ON(hyp_page_count(hyp_vm))) {
                err = -EBUSY;
                goto err_unlock;
        }

        host_kvm = hyp_vm->host_kvm;

        /* Ensure the VMID is clean before it can be reallocated */
        __kvm_tlb_flush_vmid(&hyp_vm->kvm.arch.mmu);
        remove_vm_table_entry(handle);
        hyp_spin_unlock(&vm_table_lock);

        /* Reclaim guest pages (including page-table pages) */
        mc = &host_kvm->arch.pkvm.teardown_mc;
        stage2_mc = &host_kvm->arch.pkvm.stage2_teardown_mc;
        reclaim_pgtable_pages(hyp_vm, stage2_mc);
        unpin_host_vcpus(hyp_vm->vcpus, hyp_vm->kvm.created_vcpus);

        /* Push the metadata pages to the teardown memcache */
        for (idx = 0; idx < hyp_vm->kvm.created_vcpus; ++idx) {
                struct pkvm_hyp_vcpu *hyp_vcpu = hyp_vm->vcpus[idx];
                struct kvm_hyp_memcache *vcpu_mc;

                if (!hyp_vcpu)
                        continue;

                vcpu_mc = &hyp_vcpu->vcpu.arch.pkvm_memcache;

                while (vcpu_mc->nr_pages) {
                        void *addr = pop_hyp_memcache(vcpu_mc, hyp_phys_to_virt);

                        push_hyp_memcache(stage2_mc, addr, hyp_virt_to_phys);
                        unmap_donated_memory_noclear(addr, PAGE_SIZE);
                }

                teardown_donated_memory(mc, hyp_vcpu, sizeof(*hyp_vcpu));
        }

        vm_size = pkvm_get_hyp_vm_size(hyp_vm->kvm.created_vcpus);
        teardown_donated_memory(mc, hyp_vm, vm_size);
        hyp_unpin_shared_mem(host_kvm, host_kvm + 1);
        return 0;

err_unlock:
        hyp_spin_unlock(&vm_table_lock);
        return err;
}