// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Test handler for the s390x DIAGNOSE 0x0318 instruction.
 *
 * Copyright (C) 2020, IBM
 */

#include "test_util.h"
#include "kvm_util.h"

#define ICPT_INSTRUCTION        0x04
#define IPA0_DIAG               0x8300

static void guest_code(void)
{
        uint64_t diag318_info = 0x12345678;

        asm volatile ("diag %0,0,0x318\n" : : "d" (diag318_info));
}

/*
 * The DIAGNOSE 0x0318 instruction call must be handled via userspace. As such,
 * we create an ad-hoc VM here to handle the instruction then extract the
 * necessary data. It is up to the caller to decide what to do with that data.
 */
static uint64_t diag318_handler(void)
{
        struct kvm_vcpu *vcpu;
        struct kvm_vm *vm;
        struct kvm_run *run;
        uint64_t reg;
        uint64_t diag318_info;

        vm = vm_create_with_one_vcpu(&vcpu, guest_code);
        vcpu_run(vcpu);
        run = vcpu->run;

        TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_S390_SIEIC);
        TEST_ASSERT(run->s390_sieic.icptcode == ICPT_INSTRUCTION,
                    "Unexpected intercept code: 0x%x", run->s390_sieic.icptcode);
        TEST_ASSERT((run->s390_sieic.ipa & 0xff00) == IPA0_DIAG,
                    "Unexpected IPA0 code: 0x%x", (run->s390_sieic.ipa & 0xff00));

        reg = (run->s390_sieic.ipa & 0x00f0) >> 4;
        diag318_info = run->s.regs.gprs[reg];

        TEST_ASSERT(diag318_info != 0, "DIAGNOSE 0x0318 info not set");

        kvm_vm_free(vm);

        return diag318_info;
}

uint64_t get_diag318_info(void)
{
        static uint64_t diag318_info;
        static bool printed_skip;

        /*
         * If KVM does not support diag318, then return 0 to
         * ensure tests do not break.
         */
        if (!kvm_has_cap(KVM_CAP_S390_DIAG318)) {
                if (!printed_skip) {
                        fprintf(stdout, "KVM_CAP_S390_DIAG318 not supported. "
                                "Skipping diag318 test.\n");
                        printed_skip = true;
                }
                return 0;
        }

        /*
         * If a test has previously requested the diag318 info,
         * then don't bother spinning up a temporary VM again.
         */
        if (!diag318_info)
                diag318_info = diag318_handler();

        return diag318_info;
}