// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020, Google LLC.
 *
 * Tests for KVM paravirtual feature disablement
 */
#include <asm/kvm_para.h>
#include <linux/kvm_para.h>
#include <stdint.h>

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

extern unsigned char rdmsr_start;
extern unsigned char rdmsr_end;

static u64 do_rdmsr(u32 idx)
{
        u32 lo, hi;

        asm volatile("rdmsr_start: rdmsr;"
                     "rdmsr_end:"
                     : "=a"(lo), "=c"(hi)
                     : "c"(idx));

        return (((u64) hi) << 32) | lo;
}

extern unsigned char wrmsr_start;
extern unsigned char wrmsr_end;

static void do_wrmsr(u32 idx, u64 val)
{
        u32 lo, hi;

        lo = val;
        hi = val >> 32;

        asm volatile("wrmsr_start: wrmsr;"
                     "wrmsr_end:"
                     : : "a"(lo), "c"(idx), "d"(hi));
}

static int nr_gp;

static void guest_gp_handler(struct ex_regs *regs)
{
        unsigned char *rip = (unsigned char *)regs->rip;
        bool r, w;

        r = rip == &rdmsr_start;
        w = rip == &wrmsr_start;
        GUEST_ASSERT(r || w);

        nr_gp++;

        if (r)
                regs->rip = (uint64_t)&rdmsr_end;
        else
                regs->rip = (uint64_t)&wrmsr_end;
}

struct msr_data {
        uint32_t idx;
        const char *name;
};

#define TEST_MSR(msr) { .idx = msr, .name = #msr }
#define UCALL_PR_MSR 0xdeadbeef
#define PR_MSR(msr) ucall(UCALL_PR_MSR, 1, msr)

/*
 * KVM paravirtual msrs to test. Expect a #GP if any of these msrs are read or
 * written, as the KVM_CPUID_FEATURES leaf is cleared.
 */
static struct msr_data msrs_to_test[] = {
        TEST_MSR(MSR_KVM_SYSTEM_TIME),
        TEST_MSR(MSR_KVM_SYSTEM_TIME_NEW),
        TEST_MSR(MSR_KVM_WALL_CLOCK),
        TEST_MSR(MSR_KVM_WALL_CLOCK_NEW),
        TEST_MSR(MSR_KVM_ASYNC_PF_EN),
        TEST_MSR(MSR_KVM_STEAL_TIME),
        TEST_MSR(MSR_KVM_PV_EOI_EN),
        TEST_MSR(MSR_KVM_POLL_CONTROL),
        TEST_MSR(MSR_KVM_ASYNC_PF_INT),
        TEST_MSR(MSR_KVM_ASYNC_PF_ACK),
};

static void test_msr(struct msr_data *msr)
{
        PR_MSR(msr);
        do_rdmsr(msr->idx);
        GUEST_ASSERT(READ_ONCE(nr_gp) == 1);

        nr_gp = 0;
        do_wrmsr(msr->idx, 0);
        GUEST_ASSERT(READ_ONCE(nr_gp) == 1);
        nr_gp = 0;
}

struct hcall_data {
        uint64_t nr;
        const char *name;
};

#define TEST_HCALL(hc) { .nr = hc, .name = #hc }
#define UCALL_PR_HCALL 0xdeadc0de
#define PR_HCALL(hc) ucall(UCALL_PR_HCALL, 1, hc)

/*
 * KVM hypercalls to test. Expect -KVM_ENOSYS when called, as the corresponding
 * features have been cleared in KVM_CPUID_FEATURES.
 */
static struct hcall_data hcalls_to_test[] = {
        TEST_HCALL(KVM_HC_KICK_CPU),
        TEST_HCALL(KVM_HC_SEND_IPI),
        TEST_HCALL(KVM_HC_SCHED_YIELD),
};

static void test_hcall(struct hcall_data *hc)
{
        uint64_t r;

        PR_HCALL(hc);
        r = kvm_hypercall(hc->nr, 0, 0, 0, 0);
        GUEST_ASSERT(r == -KVM_ENOSYS);
}

static void guest_main(void)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(msrs_to_test); i++) {
                test_msr(&msrs_to_test[i]);
        }

        for (i = 0; i < ARRAY_SIZE(hcalls_to_test); i++) {
                test_hcall(&hcalls_to_test[i]);
        }

        GUEST_DONE();
}

static void clear_kvm_cpuid_features(struct kvm_cpuid2 *cpuid)
{
        struct kvm_cpuid_entry2 ent = {0};

        ent.function = KVM_CPUID_FEATURES;
        TEST_ASSERT(set_cpuid(cpuid, &ent),
                    "failed to clear KVM_CPUID_FEATURES leaf");
}

static void pr_msr(struct ucall *uc)
{
        struct msr_data *msr = (struct msr_data *)uc->args[0];

        pr_info("testing msr: %s (%#x)\n", msr->name, msr->idx);
}

static void pr_hcall(struct ucall *uc)
{
        struct hcall_data *hc = (struct hcall_data *)uc->args[0];

        pr_info("testing hcall: %s (%lu)\n", hc->name, hc->nr);
}

static void handle_abort(struct ucall *uc)
{
        TEST_FAIL("%s at %s:%ld", (const char *)uc->args[0],
                  __FILE__, uc->args[1]);
}

#define VCPU_ID 0

static void enter_guest(struct kvm_vm *vm)
{
        struct kvm_run *run;
        struct ucall uc;
        int r;

        run = vcpu_state(vm, VCPU_ID);

        while (true) {
                r = _vcpu_run(vm, VCPU_ID);
                TEST_ASSERT(!r, "vcpu_run failed: %d\n", r);
                TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
                            "unexpected exit reason: %u (%s)",
                            run->exit_reason, exit_reason_str(run->exit_reason));

                switch (get_ucall(vm, VCPU_ID, &uc)) {
                case UCALL_PR_MSR:
                        pr_msr(&uc);
                        break;
                case UCALL_PR_HCALL:
                        pr_hcall(&uc);
                        break;
                case UCALL_ABORT:
                        handle_abort(&uc);
                        return;
                case UCALL_DONE:
                        return;
                }
        }
}

int main(void)
{
        struct kvm_enable_cap cap = {0};
        struct kvm_cpuid2 *best;
        struct kvm_vm *vm;

        if (!kvm_check_cap(KVM_CAP_ENFORCE_PV_FEATURE_CPUID)) {
                print_skip("KVM_CAP_ENFORCE_PV_FEATURE_CPUID not supported");
                exit(KSFT_SKIP);
        }

        vm = vm_create_default(VCPU_ID, 0, guest_main);

        cap.cap = KVM_CAP_ENFORCE_PV_FEATURE_CPUID;
        cap.args[0] = 1;
        vcpu_enable_cap(vm, VCPU_ID, &cap);

        best = kvm_get_supported_cpuid();
        clear_kvm_cpuid_features(best);
        vcpu_set_cpuid(vm, VCPU_ID, best);

        vm_init_descriptor_tables(vm);
        vcpu_init_descriptor_tables(vm, VCPU_ID);
        vm_handle_exception(vm, GP_VECTOR, guest_gp_handler);

        enter_guest(vm);
        kvm_vm_free(vm);
}