// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/types.h>
#include <signal.h>
#include <errno.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/atomic.h>
#include <linux/sizes.h>

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

static bool mprotect_ro_done;
static bool all_vcpus_hit_ro_fault;

static void guest_code(uint64_t start_gpa, uint64_t end_gpa, uint64_t stride)
{
        uint64_t gpa;
        int i;

        for (i = 0; i < 2; i++) {
                for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
                        vcpu_arch_put_guest(*((volatile uint64_t *)gpa), gpa);
                GUEST_SYNC(i);
        }

        for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
                *((volatile uint64_t *)gpa);
        GUEST_SYNC(2);

        /*
         * Write to the region while mprotect(PROT_READ) is underway.  Keep
         * looping until the memory is guaranteed to be read-only and a fault
         * has occurred, otherwise vCPUs may complete their writes and advance
         * to the next stage prematurely.
         *
         * For architectures that support skipping the faulting instruction,
         * generate the store via inline assembly to ensure the exact length
         * of the instruction is known and stable (vcpu_arch_put_guest() on
         * fixed-length architectures should work, but the cost of paranoia
         * is low in this case).  For x86, hand-code the exact opcode so that
         * there is no room for variability in the generated instruction.
         */
        do {
                for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
#ifdef __x86_64__
                        asm volatile(".byte 0x48,0x89,0x00" :: "a"(gpa) : "memory"); /* mov %rax, (%rax) */
#elif defined(__aarch64__)
                        asm volatile("str %0, [%0]" :: "r" (gpa) : "memory");
#else
                        vcpu_arch_put_guest(*((volatile uint64_t *)gpa), gpa);
#endif
        } while (!READ_ONCE(mprotect_ro_done) || !READ_ONCE(all_vcpus_hit_ro_fault));

        /*
         * Only architectures that write the entire range can explicitly sync,
         * as other architectures will be stuck on the write fault.
         */
#if defined(__x86_64__) || defined(__aarch64__)
        GUEST_SYNC(3);
#endif

        for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
                vcpu_arch_put_guest(*((volatile uint64_t *)gpa), gpa);
        GUEST_SYNC(4);

        GUEST_ASSERT(0);
}

struct vcpu_info {
        struct kvm_vcpu *vcpu;
        uint64_t start_gpa;
        uint64_t end_gpa;
};

static int nr_vcpus;
static atomic_t rendezvous;
static atomic_t nr_ro_faults;

static void rendezvous_with_boss(void)
{
        int orig = atomic_read(&rendezvous);

        if (orig > 0) {
                atomic_dec_and_test(&rendezvous);
                while (atomic_read(&rendezvous) > 0)
                        cpu_relax();
        } else {
                atomic_inc(&rendezvous);
                while (atomic_read(&rendezvous) < 0)
                        cpu_relax();
        }
}

static void assert_sync_stage(struct kvm_vcpu *vcpu, int stage)
{
        struct ucall uc;

        TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_SYNC);
        TEST_ASSERT_EQ(uc.args[1], stage);
}

static void run_vcpu(struct kvm_vcpu *vcpu, int stage)
{
        vcpu_run(vcpu);
        assert_sync_stage(vcpu, stage);
}

static void *vcpu_worker(void *data)
{
        struct kvm_sregs __maybe_unused sregs;
        struct vcpu_info *info = data;
        struct kvm_vcpu *vcpu = info->vcpu;
        struct kvm_vm *vm = vcpu->vm;
        int r;

        vcpu_args_set(vcpu, 3, info->start_gpa, info->end_gpa, vm->page_size);

        rendezvous_with_boss();

        /* Stage 0, write all of guest memory. */
        run_vcpu(vcpu, 0);
        rendezvous_with_boss();
#ifdef __x86_64__
        vcpu_sregs_get(vcpu, &sregs);
        /* Toggle CR0.WP to trigger a MMU context reset. */
        sregs.cr0 ^= X86_CR0_WP;
        vcpu_sregs_set(vcpu, &sregs);
#endif
        rendezvous_with_boss();

        /* Stage 1, re-write all of guest memory. */
        run_vcpu(vcpu, 1);
        rendezvous_with_boss();

        /* Stage 2, read all of guest memory, which is now read-only. */
        run_vcpu(vcpu, 2);

        /*
         * Stage 3, write guest memory and verify KVM returns -EFAULT for once
         * the mprotect(PROT_READ) lands.  Only architectures that support
         * validating *all* of guest memory sync for this stage, as vCPUs will
         * be stuck on the faulting instruction for other architectures.  Go to
         * stage 3 without a rendezvous
         */
        r = _vcpu_run(vcpu);
        TEST_ASSERT(r == -1 && errno == EFAULT,
                    "Expected EFAULT on write to RO memory, got r = %d, errno = %d", r, errno);

        atomic_inc(&nr_ro_faults);
        if (atomic_read(&nr_ro_faults) == nr_vcpus) {
                WRITE_ONCE(all_vcpus_hit_ro_fault, true);
                sync_global_to_guest(vm, all_vcpus_hit_ro_fault);
        }

#if defined(__x86_64__) || defined(__aarch64__)
        /*
         * Verify *all* writes from the guest hit EFAULT due to the VMA now
         * being read-only.  x86 and arm64 only at this time as skipping the
         * instruction that hits the EFAULT requires advancing the program
         * counter, which is arch specific and relies on inline assembly.
         */
#ifdef __x86_64__
        vcpu->run->kvm_valid_regs = KVM_SYNC_X86_REGS;
#endif
        for (;;) {
                r = _vcpu_run(vcpu);
                if (!r)
                        break;
                TEST_ASSERT_EQ(errno, EFAULT);
#if defined(__x86_64__)
                WRITE_ONCE(vcpu->run->kvm_dirty_regs, KVM_SYNC_X86_REGS);
                vcpu->run->s.regs.regs.rip += 3;
#elif defined(__aarch64__)
                vcpu_set_reg(vcpu, ARM64_CORE_REG(regs.pc),
                             vcpu_get_reg(vcpu, ARM64_CORE_REG(regs.pc)) + 4);
#endif

        }
        assert_sync_stage(vcpu, 3);
#endif /* __x86_64__ || __aarch64__ */
        rendezvous_with_boss();

        /*
         * Stage 4.  Run to completion, waiting for mprotect(PROT_WRITE) to
         * make the memory writable again.
         */
        do {
                r = _vcpu_run(vcpu);
        } while (r && errno == EFAULT);
        TEST_ASSERT_EQ(r, 0);
        assert_sync_stage(vcpu, 4);
        rendezvous_with_boss();

        return NULL;
}

static pthread_t *spawn_workers(struct kvm_vm *vm, struct kvm_vcpu **vcpus,
                                uint64_t start_gpa, uint64_t end_gpa)
{
        struct vcpu_info *info;
        uint64_t gpa, nr_bytes;
        pthread_t *threads;
        int i;

        threads = malloc(nr_vcpus * sizeof(*threads));
        TEST_ASSERT(threads, "Failed to allocate vCPU threads");

        info = malloc(nr_vcpus * sizeof(*info));
        TEST_ASSERT(info, "Failed to allocate vCPU gpa ranges");

        nr_bytes = ((end_gpa - start_gpa) / nr_vcpus) &
                        ~((uint64_t)vm->page_size - 1);
        TEST_ASSERT(nr_bytes, "C'mon, no way you have %d CPUs", nr_vcpus);

        for (i = 0, gpa = start_gpa; i < nr_vcpus; i++, gpa += nr_bytes) {
                info[i].vcpu = vcpus[i];
                info[i].start_gpa = gpa;
                info[i].end_gpa = gpa + nr_bytes;
                pthread_create(&threads[i], NULL, vcpu_worker, &info[i]);
        }
        return threads;
}

static void rendezvous_with_vcpus(struct timespec *time, const char *name)
{
        int i, rendezvoused;

        pr_info("Waiting for vCPUs to finish %s...\n", name);

        rendezvoused = atomic_read(&rendezvous);
        for (i = 0; abs(rendezvoused) != 1; i++) {
                usleep(100);
                if (!(i & 0x3f))
                        pr_info("\r%d vCPUs haven't rendezvoused...",
                                abs(rendezvoused) - 1);
                rendezvoused = atomic_read(&rendezvous);
        }

        clock_gettime(CLOCK_MONOTONIC, time);

        /* Release the vCPUs after getting the time of the previous action. */
        pr_info("\rAll vCPUs finished %s, releasing...\n", name);
        if (rendezvoused > 0)
                atomic_set(&rendezvous, -nr_vcpus - 1);
        else
                atomic_set(&rendezvous, nr_vcpus + 1);
}

static void calc_default_nr_vcpus(void)
{
        cpu_set_t possible_mask;
        int r;

        r = sched_getaffinity(0, sizeof(possible_mask), &possible_mask);
        TEST_ASSERT(!r, "sched_getaffinity failed, errno = %d (%s)",
                    errno, strerror(errno));

        nr_vcpus = CPU_COUNT(&possible_mask);
        TEST_ASSERT(nr_vcpus > 0, "Uh, no CPUs?");
        if (nr_vcpus >= 2)
                nr_vcpus = nr_vcpus * 3/4;
}

int main(int argc, char *argv[])
{
        /*
         * Skip the first 4gb and slot0.  slot0 maps <1gb and is used to back
         * the guest's code, stack, and page tables.  Because selftests creates
         * an IRQCHIP, a.k.a. a local APIC, KVM creates an internal memslot
         * just below the 4gb boundary.  This test could create memory at
         * 1gb-3gb,but it's simpler to skip straight to 4gb.
         */
        const uint64_t start_gpa = SZ_4G;
        const int first_slot = 1;

        struct timespec time_start, time_run1, time_reset, time_run2, time_ro, time_rw;
        uint64_t max_gpa, gpa, slot_size, max_mem, i;
        int max_slots, slot, opt, fd;
        bool hugepages = false;
        struct kvm_vcpu **vcpus;
        pthread_t *threads;
        struct kvm_vm *vm;
        void *mem;

        /*
         * Default to 2gb so that maxing out systems with MAXPHADDR=46, which
         * are quite common for x86, requires changing only max_mem (KVM allows
         * 32k memslots, 32k * 2gb == ~64tb of guest memory).
         */
        slot_size = SZ_2G;

        max_slots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS);
        TEST_ASSERT(max_slots > first_slot, "KVM is broken");

        /* All KVM MMUs should be able to survive a 128gb guest. */
        max_mem = 128ull * SZ_1G;

        calc_default_nr_vcpus();

        while ((opt = getopt(argc, argv, "c:h:m:s:H")) != -1) {
                switch (opt) {
                case 'c':
                        nr_vcpus = atoi_positive("Number of vCPUs", optarg);
                        break;
                case 'm':
                        max_mem = 1ull * atoi_positive("Memory size", optarg) * SZ_1G;
                        break;
                case 's':
                        slot_size = 1ull * atoi_positive("Slot size", optarg) * SZ_1G;
                        break;
                case 'H':
                        hugepages = true;
                        break;
                case 'h':
                default:
                        printf("usage: %s [-c nr_vcpus] [-m max_mem_in_gb] [-s slot_size_in_gb] [-H]\n", argv[0]);
                        exit(1);
                }
        }

        vcpus = malloc(nr_vcpus * sizeof(*vcpus));
        TEST_ASSERT(vcpus, "Failed to allocate vCPU array");

        vm = __vm_create_with_vcpus(VM_SHAPE_DEFAULT, nr_vcpus,
#ifdef __x86_64__
                                    max_mem / SZ_1G,
#else
                                    max_mem / vm_guest_mode_params[VM_MODE_DEFAULT].page_size,
#endif
                                    guest_code, vcpus);

        max_gpa = vm->max_gfn << vm->page_shift;
        TEST_ASSERT(max_gpa > (4 * slot_size), "MAXPHYADDR <4gb ");

        fd = kvm_memfd_alloc(slot_size, hugepages);
        mem = kvm_mmap(slot_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd);

        TEST_ASSERT(!madvise(mem, slot_size, MADV_NOHUGEPAGE), "madvise() failed");

        /* Pre-fault the memory to avoid taking mmap_sem on guest page faults. */
        for (i = 0; i < slot_size; i += vm->page_size)
                ((uint8_t *)mem)[i] = 0xaa;

        gpa = 0;
        for (slot = first_slot; slot < max_slots; slot++) {
                gpa = start_gpa + ((slot - first_slot) * slot_size);
                if (gpa + slot_size > max_gpa)
                        break;

                if ((gpa - start_gpa) >= max_mem)
                        break;

                vm_set_user_memory_region(vm, slot, 0, gpa, slot_size, mem);

#ifdef __x86_64__
                /* Identity map memory in the guest using 1gb pages. */
                virt_map_level(vm, gpa, gpa, slot_size, PG_LEVEL_1G);
#else
                virt_map(vm, gpa, gpa, slot_size >> vm->page_shift);
#endif
        }

        atomic_set(&rendezvous, nr_vcpus + 1);
        threads = spawn_workers(vm, vcpus, start_gpa, gpa);

        free(vcpus);
        vcpus = NULL;

        pr_info("Running with %lugb of guest memory and %u vCPUs\n",
                (gpa - start_gpa) / SZ_1G, nr_vcpus);

        rendezvous_with_vcpus(&time_start, "spawning");
        rendezvous_with_vcpus(&time_run1, "run 1");
        rendezvous_with_vcpus(&time_reset, "reset");
        rendezvous_with_vcpus(&time_run2, "run 2");

        mprotect(mem, slot_size, PROT_READ);
        mprotect_ro_done = true;
        sync_global_to_guest(vm, mprotect_ro_done);

        rendezvous_with_vcpus(&time_ro, "mprotect RO");
        mprotect(mem, slot_size, PROT_READ | PROT_WRITE);
        rendezvous_with_vcpus(&time_rw, "mprotect RW");

        time_rw    = timespec_sub(time_rw,     time_ro);
        time_ro    = timespec_sub(time_ro,     time_run2);
        time_run2  = timespec_sub(time_run2,   time_reset);
        time_reset = timespec_sub(time_reset,  time_run1);
        time_run1  = timespec_sub(time_run1,   time_start);

        pr_info("run1 = %ld.%.9lds, reset = %ld.%.9lds, run2 = %ld.%.9lds, "
                "ro = %ld.%.9lds, rw = %ld.%.9lds\n",
                time_run1.tv_sec, time_run1.tv_nsec,
                time_reset.tv_sec, time_reset.tv_nsec,
                time_run2.tv_sec, time_run2.tv_nsec,
                time_ro.tv_sec, time_ro.tv_nsec,
                time_rw.tv_sec, time_rw.tv_nsec);

        /*
         * Delete even numbered slots (arbitrary) and unmap the first half of
         * the backing (also arbitrary) to verify KVM correctly drops all
         * references to the removed regions.
         */
        for (slot = (slot - 1) & ~1ull; slot >= first_slot; slot -= 2)
                vm_set_user_memory_region(vm, slot, 0, 0, 0, NULL);

        kvm_munmap(mem, slot_size / 2);

        /* Sanity check that the vCPUs actually ran. */
        for (i = 0; i < nr_vcpus; i++)
                pthread_join(threads[i], NULL);

        /*
         * Deliberately exit without deleting the remaining memslots or closing
         * kvm_fd to test cleanup via mmu_notifier.release.
         */
}