// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2012 Michael Ellerman, IBM Corporation.
 */

#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <linux/kvm.h>
#include <linux/err.h>

#include <linux/uaccess.h>
#include <asm/kvm_book3s.h>
#include <asm/kvm_ppc.h>
#include <asm/hvcall.h>
#include <asm/rtas.h>
#include <asm/xive.h>

#ifdef CONFIG_KVM_XICS
static void kvm_rtas_set_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
{
        u32 irq, server, priority;
        int rc;

        if (be32_to_cpu(args->nargs) != 3 || be32_to_cpu(args->nret) != 1) {
                rc = -3;
                goto out;
        }

        irq = be32_to_cpu(args->args[0]);
        server = be32_to_cpu(args->args[1]);
        priority = be32_to_cpu(args->args[2]);

        if (xics_on_xive())
                rc = kvmppc_xive_set_xive(vcpu->kvm, irq, server, priority);
        else
                rc = kvmppc_xics_set_xive(vcpu->kvm, irq, server, priority);
        if (rc)
                rc = -3;
out:
        args->rets[0] = cpu_to_be32(rc);
}

static void kvm_rtas_get_xive(struct kvm_vcpu *vcpu, struct rtas_args *args)
{
        u32 irq, server, priority;
        int rc;

        if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 3) {
                rc = -3;
                goto out;
        }

        irq = be32_to_cpu(args->args[0]);

        server = priority = 0;
        if (xics_on_xive())
                rc = kvmppc_xive_get_xive(vcpu->kvm, irq, &server, &priority);
        else
                rc = kvmppc_xics_get_xive(vcpu->kvm, irq, &server, &priority);
        if (rc) {
                rc = -3;
                goto out;
        }

        args->rets[1] = cpu_to_be32(server);
        args->rets[2] = cpu_to_be32(priority);
out:
        args->rets[0] = cpu_to_be32(rc);
}

static void kvm_rtas_int_off(struct kvm_vcpu *vcpu, struct rtas_args *args)
{
        u32 irq;
        int rc;

        if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 1) {
                rc = -3;
                goto out;
        }

        irq = be32_to_cpu(args->args[0]);

        if (xics_on_xive())
                rc = kvmppc_xive_int_off(vcpu->kvm, irq);
        else
                rc = kvmppc_xics_int_off(vcpu->kvm, irq);
        if (rc)
                rc = -3;
out:
        args->rets[0] = cpu_to_be32(rc);
}

static void kvm_rtas_int_on(struct kvm_vcpu *vcpu, struct rtas_args *args)
{
        u32 irq;
        int rc;

        if (be32_to_cpu(args->nargs) != 1 || be32_to_cpu(args->nret) != 1) {
                rc = -3;
                goto out;
        }

        irq = be32_to_cpu(args->args[0]);

        if (xics_on_xive())
                rc = kvmppc_xive_int_on(vcpu->kvm, irq);
        else
                rc = kvmppc_xics_int_on(vcpu->kvm, irq);
        if (rc)
                rc = -3;
out:
        args->rets[0] = cpu_to_be32(rc);
}
#endif /* CONFIG_KVM_XICS */

struct rtas_handler {
        void (*handler)(struct kvm_vcpu *vcpu, struct rtas_args *args);
        char *name;
};

static struct rtas_handler rtas_handlers[] = {
#ifdef CONFIG_KVM_XICS
        { .name = "ibm,set-xive", .handler = kvm_rtas_set_xive },
        { .name = "ibm,get-xive", .handler = kvm_rtas_get_xive },
        { .name = "ibm,int-off",  .handler = kvm_rtas_int_off },
        { .name = "ibm,int-on",   .handler = kvm_rtas_int_on },
#endif
};

struct rtas_token_definition {
        struct list_head list;
        struct rtas_handler *handler;
        u64 token;
};

static int rtas_name_matches(char *s1, char *s2)
{
        struct kvm_rtas_token_args args;
        return !strncmp(s1, s2, sizeof(args.name));
}

static int rtas_token_undefine(struct kvm *kvm, char *name)
{
        struct rtas_token_definition *d, *tmp;

        lockdep_assert_held(&kvm->arch.rtas_token_lock);

        list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
                if (rtas_name_matches(d->handler->name, name)) {
                        list_del(&d->list);
                        kfree(d);
                        return 0;
                }
        }

        /* It's not an error to undefine an undefined token */
        return 0;
}

static int rtas_token_define(struct kvm *kvm, char *name, u64 token)
{
        struct rtas_token_definition *d;
        struct rtas_handler *h = NULL;
        bool found;
        int i;

        lockdep_assert_held(&kvm->arch.rtas_token_lock);

        list_for_each_entry(d, &kvm->arch.rtas_tokens, list) {
                if (d->token == token)
                        return -EEXIST;
        }

        found = false;
        for (i = 0; i < ARRAY_SIZE(rtas_handlers); i++) {
                h = &rtas_handlers[i];
                if (rtas_name_matches(h->name, name)) {
                        found = true;
                        break;
                }
        }

        if (!found)
                return -ENOENT;

        d = kzalloc(sizeof(*d), GFP_KERNEL);
        if (!d)
                return -ENOMEM;

        d->handler = h;
        d->token = token;

        list_add_tail(&d->list, &kvm->arch.rtas_tokens);

        return 0;
}

int kvm_vm_ioctl_rtas_define_token(struct kvm *kvm, void __user *argp)
{
        struct kvm_rtas_token_args args;
        int rc;

        if (copy_from_user(&args, argp, sizeof(args)))
                return -EFAULT;

        mutex_lock(&kvm->arch.rtas_token_lock);

        if (args.token)
                rc = rtas_token_define(kvm, args.name, args.token);
        else
                rc = rtas_token_undefine(kvm, args.name);

        mutex_unlock(&kvm->arch.rtas_token_lock);

        return rc;
}

int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu)
{
        struct rtas_token_definition *d;
        struct rtas_args args;
        rtas_arg_t *orig_rets;
        gpa_t args_phys;
        int rc;

        /*
         * r4 contains the guest physical address of the RTAS args
         * Mask off the top 4 bits since this is a guest real address
         */
        args_phys = kvmppc_get_gpr(vcpu, 4) & KVM_PAM;

        vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
        rc = kvm_read_guest(vcpu->kvm, args_phys, &args, sizeof(args));
        srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
        if (rc)
                goto fail;

        /*
         * args->rets is a pointer into args->args. Now that we've
         * copied args we need to fix it up to point into our copy,
         * not the guest args. We also need to save the original
         * value so we can restore it on the way out.
         */
        orig_rets = args.rets;
        if (be32_to_cpu(args.nargs) >= ARRAY_SIZE(args.args)) {
                /*
                 * Don't overflow our args array: ensure there is room for
                 * at least rets[0] (even if the call specifies 0 nret).
                 *
                 * Each handler must then check for the correct nargs and nret
                 * values, but they may always return failure in rets[0].
                 */
                rc = -EINVAL;
                goto fail;
        }
        args.rets = &args.args[be32_to_cpu(args.nargs)];

        mutex_lock(&vcpu->kvm->arch.rtas_token_lock);

        rc = -ENOENT;
        list_for_each_entry(d, &vcpu->kvm->arch.rtas_tokens, list) {
                if (d->token == be32_to_cpu(args.token)) {
                        d->handler->handler(vcpu, &args);
                        rc = 0;
                        break;
                }
        }

        mutex_unlock(&vcpu->kvm->arch.rtas_token_lock);

        if (rc == 0) {
                args.rets = orig_rets;
                rc = kvm_write_guest(vcpu->kvm, args_phys, &args, sizeof(args));
                if (rc)
                        goto fail;
        }

        return rc;

fail:
        /*
         * We only get here if the guest has called RTAS with a bogus
         * args pointer or nargs/nret values that would overflow the
         * array. That means we can't get to the args, and so we can't
         * fail the RTAS call. So fail right out to userspace, which
         * should kill the guest.
         *
         * SLOF should actually pass the hcall return value from the
         * rtas handler call in r3, so enter_rtas could be modified to
         * return a failure indication in r3 and we could return such
         * errors to the guest rather than failing to host userspace.
         * However old guests that don't test for failure could then
         * continue silently after errors, so for now we won't do this.
         */
        return rc;
}
EXPORT_SYMBOL_GPL(kvmppc_rtas_hcall);

void kvmppc_rtas_tokens_free(struct kvm *kvm)
{
        struct rtas_token_definition *d, *tmp;

        list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) {
                list_del(&d->list);
                kfree(d);
        }
}