// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022, Google LLC.
 */
#include <fcntl.h>
#include <limits.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>

#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kvm_para.h>
#include <linux/memfd.h>
#include <linux/sizes.h>

#include <test_util.h>
#include <kvm_util.h>
#include <processor.h>

#define BASE_DATA_SLOT          10
#define BASE_DATA_GPA           ((uint64_t)(1ull << 32))
#define PER_CPU_DATA_SIZE       ((uint64_t)(SZ_2M + PAGE_SIZE))

/* Horrific macro so that the line info is captured accurately :-( */
#define memcmp_g(gpa, pattern,  size)                                                           \
do {                                                                                            \
        uint8_t *mem = (uint8_t *)gpa;                                                          \
        size_t i;                                                                               \
                                                                                                \
        for (i = 0; i < size; i++)                                                              \
                __GUEST_ASSERT(mem[i] == pattern,                                               \
                               "Guest expected 0x%x at offset %lu (gpa 0x%lx), got 0x%x",       \
                               pattern, i, gpa + i, mem[i]);                                    \
} while (0)

static void memcmp_h(uint8_t *mem, uint64_t gpa, uint8_t pattern, size_t size)
{
        size_t i;

        for (i = 0; i < size; i++)
                TEST_ASSERT(mem[i] == pattern,
                            "Host expected 0x%x at gpa 0x%lx, got 0x%x",
                            pattern, gpa + i, mem[i]);
}

/*
 * Run memory conversion tests with explicit conversion:
 * Execute KVM hypercall to map/unmap gpa range which will cause userspace exit
 * to back/unback private memory. Subsequent accesses by guest to the gpa range
 * will not cause exit to userspace.
 *
 * Test memory conversion scenarios with following steps:
 * 1) Access private memory using private access and verify that memory contents
 *   are not visible to userspace.
 * 2) Convert memory to shared using explicit conversions and ensure that
 *   userspace is able to access the shared regions.
 * 3) Convert memory back to private using explicit conversions and ensure that
 *   userspace is again not able to access converted private regions.
 */

#define GUEST_STAGE(o, s) { .offset = o, .size = s }

enum ucall_syncs {
        SYNC_SHARED,
        SYNC_PRIVATE,
};

static void guest_sync_shared(uint64_t gpa, uint64_t size,
                              uint8_t current_pattern, uint8_t new_pattern)
{
        GUEST_SYNC5(SYNC_SHARED, gpa, size, current_pattern, new_pattern);
}

static void guest_sync_private(uint64_t gpa, uint64_t size, uint8_t pattern)
{
        GUEST_SYNC4(SYNC_PRIVATE, gpa, size, pattern);
}

/* Arbitrary values, KVM doesn't care about the attribute flags. */
#define MAP_GPA_SET_ATTRIBUTES  BIT(0)
#define MAP_GPA_SHARED          BIT(1)
#define MAP_GPA_DO_FALLOCATE    BIT(2)

static void guest_map_mem(uint64_t gpa, uint64_t size, bool map_shared,
                          bool do_fallocate)
{
        uint64_t flags = MAP_GPA_SET_ATTRIBUTES;

        if (map_shared)
                flags |= MAP_GPA_SHARED;
        if (do_fallocate)
                flags |= MAP_GPA_DO_FALLOCATE;
        kvm_hypercall_map_gpa_range(gpa, size, flags);
}

static void guest_map_shared(uint64_t gpa, uint64_t size, bool do_fallocate)
{
        guest_map_mem(gpa, size, true, do_fallocate);
}

static void guest_map_private(uint64_t gpa, uint64_t size, bool do_fallocate)
{
        guest_map_mem(gpa, size, false, do_fallocate);
}

struct {
        uint64_t offset;
        uint64_t size;
} static const test_ranges[] = {
        GUEST_STAGE(0, PAGE_SIZE),
        GUEST_STAGE(0, SZ_2M),
        GUEST_STAGE(PAGE_SIZE, PAGE_SIZE),
        GUEST_STAGE(PAGE_SIZE, SZ_2M),
        GUEST_STAGE(SZ_2M, PAGE_SIZE),
};

static void guest_test_explicit_conversion(uint64_t base_gpa, bool do_fallocate)
{
        const uint8_t def_p = 0xaa;
        const uint8_t init_p = 0xcc;
        uint64_t j;
        int i;

        /* Memory should be shared by default. */
        memset((void *)base_gpa, def_p, PER_CPU_DATA_SIZE);
        memcmp_g(base_gpa, def_p, PER_CPU_DATA_SIZE);
        guest_sync_shared(base_gpa, PER_CPU_DATA_SIZE, def_p, init_p);

        memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE);

        for (i = 0; i < ARRAY_SIZE(test_ranges); i++) {
                uint64_t gpa = base_gpa + test_ranges[i].offset;
                uint64_t size = test_ranges[i].size;
                uint8_t p1 = 0x11;
                uint8_t p2 = 0x22;
                uint8_t p3 = 0x33;
                uint8_t p4 = 0x44;

                /*
                 * Set the test region to pattern one to differentiate it from
                 * the data range as a whole (contains the initial pattern).
                 */
                memset((void *)gpa, p1, size);

                /*
                 * Convert to private, set and verify the private data, and
                 * then verify that the rest of the data (map shared) still
                 * holds the initial pattern, and that the host always sees the
                 * shared memory (initial pattern).  Unlike shared memory,
                 * punching a hole in private memory is destructive, i.e.
                 * previous values aren't guaranteed to be preserved.
                 */
                guest_map_private(gpa, size, do_fallocate);

                if (size > PAGE_SIZE) {
                        memset((void *)gpa, p2, PAGE_SIZE);
                        goto skip;
                }

                memset((void *)gpa, p2, size);
                guest_sync_private(gpa, size, p1);

                /*
                 * Verify that the private memory was set to pattern two, and
                 * that shared memory still holds the initial pattern.
                 */
                memcmp_g(gpa, p2, size);
                if (gpa > base_gpa)
                        memcmp_g(base_gpa, init_p, gpa - base_gpa);
                if (gpa + size < base_gpa + PER_CPU_DATA_SIZE)
                        memcmp_g(gpa + size, init_p,
                                 (base_gpa + PER_CPU_DATA_SIZE) - (gpa + size));

                /*
                 * Convert odd-number page frames back to shared to verify KVM
                 * also correctly handles holes in private ranges.
                 */
                for (j = 0; j < size; j += PAGE_SIZE) {
                        if ((j >> PAGE_SHIFT) & 1) {
                                guest_map_shared(gpa + j, PAGE_SIZE, do_fallocate);
                                guest_sync_shared(gpa + j, PAGE_SIZE, p1, p3);

                                memcmp_g(gpa + j, p3, PAGE_SIZE);
                        } else {
                                guest_sync_private(gpa + j, PAGE_SIZE, p1);
                        }
                }

skip:
                /*
                 * Convert the entire region back to shared, explicitly write
                 * pattern three to fill in the even-number frames before
                 * asking the host to verify (and write pattern four).
                 */
                guest_map_shared(gpa, size, do_fallocate);
                memset((void *)gpa, p3, size);
                guest_sync_shared(gpa, size, p3, p4);
                memcmp_g(gpa, p4, size);

                /* Reset the shared memory back to the initial pattern. */
                memset((void *)gpa, init_p, size);

                /*
                 * Free (via PUNCH_HOLE) *all* private memory so that the next
                 * iteration starts from a clean slate, e.g. with respect to
                 * whether or not there are pages/folios in guest_mem.
                 */
                guest_map_shared(base_gpa, PER_CPU_DATA_SIZE, true);
        }
}

static void guest_punch_hole(uint64_t gpa, uint64_t size)
{
        /* "Mapping" memory shared via fallocate() is done via PUNCH_HOLE. */
        uint64_t flags = MAP_GPA_SHARED | MAP_GPA_DO_FALLOCATE;

        kvm_hypercall_map_gpa_range(gpa, size, flags);
}

/*
 * Test that PUNCH_HOLE actually frees memory by punching holes without doing a
 * proper conversion.  Freeing (PUNCH_HOLE) should zap SPTEs, and reallocating
 * (subsequent fault) should zero memory.
 */
static void guest_test_punch_hole(uint64_t base_gpa, bool precise)
{
        const uint8_t init_p = 0xcc;
        int i;

        /*
         * Convert the entire range to private, this testcase is all about
         * punching holes in guest_memfd, i.e. shared mappings aren't needed.
         */
        guest_map_private(base_gpa, PER_CPU_DATA_SIZE, false);

        for (i = 0; i < ARRAY_SIZE(test_ranges); i++) {
                uint64_t gpa = base_gpa + test_ranges[i].offset;
                uint64_t size = test_ranges[i].size;

                /*
                 * Free all memory before each iteration, even for the !precise
                 * case where the memory will be faulted back in.  Freeing and
                 * reallocating should obviously work, and freeing all memory
                 * minimizes the probability of cross-testcase influence.
                 */
                guest_punch_hole(base_gpa, PER_CPU_DATA_SIZE);

                /* Fault-in and initialize memory, and verify the pattern. */
                if (precise) {
                        memset((void *)gpa, init_p, size);
                        memcmp_g(gpa, init_p, size);
                } else {
                        memset((void *)base_gpa, init_p, PER_CPU_DATA_SIZE);
                        memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE);
                }

                /*
                 * Punch a hole at the target range and verify that reads from
                 * the guest succeed and return zeroes.
                 */
                guest_punch_hole(gpa, size);
                memcmp_g(gpa, 0, size);
        }
}

static void guest_code(uint64_t base_gpa)
{
        /*
         * Run the conversion test twice, with and without doing fallocate() on
         * the guest_memfd backing when converting between shared and private.
         */
        guest_test_explicit_conversion(base_gpa, false);
        guest_test_explicit_conversion(base_gpa, true);

        /*
         * Run the PUNCH_HOLE test twice too, once with the entire guest_memfd
         * faulted in, once with only the target range faulted in.
         */
        guest_test_punch_hole(base_gpa, false);
        guest_test_punch_hole(base_gpa, true);
        GUEST_DONE();
}

static void handle_exit_hypercall(struct kvm_vcpu *vcpu)
{
        struct kvm_run *run = vcpu->run;
        uint64_t gpa = run->hypercall.args[0];
        uint64_t size = run->hypercall.args[1] * PAGE_SIZE;
        bool set_attributes = run->hypercall.args[2] & MAP_GPA_SET_ATTRIBUTES;
        bool map_shared = run->hypercall.args[2] & MAP_GPA_SHARED;
        bool do_fallocate = run->hypercall.args[2] & MAP_GPA_DO_FALLOCATE;
        struct kvm_vm *vm = vcpu->vm;

        TEST_ASSERT(run->hypercall.nr == KVM_HC_MAP_GPA_RANGE,
                    "Wanted MAP_GPA_RANGE (%u), got '%llu'",
                    KVM_HC_MAP_GPA_RANGE, run->hypercall.nr);

        if (do_fallocate)
                vm_guest_mem_fallocate(vm, gpa, size, map_shared);

        if (set_attributes)
                vm_set_memory_attributes(vm, gpa, size,
                                         map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE);
        run->hypercall.ret = 0;
}

static bool run_vcpus;

static void *__test_mem_conversions(void *__vcpu)
{
        struct kvm_vcpu *vcpu = __vcpu;
        struct kvm_run *run = vcpu->run;
        struct kvm_vm *vm = vcpu->vm;
        struct ucall uc;

        while (!READ_ONCE(run_vcpus))
                ;

        for ( ;; ) {
                vcpu_run(vcpu);

                if (run->exit_reason == KVM_EXIT_HYPERCALL) {
                        handle_exit_hypercall(vcpu);
                        continue;
                }

                TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
                            "Wanted KVM_EXIT_IO, got exit reason: %u (%s)",
                            run->exit_reason, exit_reason_str(run->exit_reason));

                switch (get_ucall(vcpu, &uc)) {
                case UCALL_ABORT:
                        REPORT_GUEST_ASSERT(uc);
                case UCALL_SYNC: {
                        uint64_t gpa  = uc.args[1];
                        size_t size = uc.args[2];
                        size_t i;

                        TEST_ASSERT(uc.args[0] == SYNC_SHARED ||
                                    uc.args[0] == SYNC_PRIVATE,
                                    "Unknown sync command '%ld'", uc.args[0]);

                        for (i = 0; i < size; i += vm->page_size) {
                                size_t nr_bytes = min_t(size_t, vm->page_size, size - i);
                                uint8_t *hva = addr_gpa2hva(vm, gpa + i);

                                /* In all cases, the host should observe the shared data. */
                                memcmp_h(hva, gpa + i, uc.args[3], nr_bytes);

                                /* For shared, write the new pattern to guest memory. */
                                if (uc.args[0] == SYNC_SHARED)
                                        memset(hva, uc.args[4], nr_bytes);
                        }
                        break;
                }
                case UCALL_DONE:
                        return NULL;
                default:
                        TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
                }
        }
}

static void test_mem_conversions(enum vm_mem_backing_src_type src_type, uint32_t nr_vcpus,
                                 uint32_t nr_memslots)
{
        /*
         * Allocate enough memory so that each vCPU's chunk of memory can be
         * naturally aligned with respect to the size of the backing store.
         */
        const size_t alignment = max_t(size_t, SZ_2M, get_backing_src_pagesz(src_type));
        const size_t per_cpu_size = align_up(PER_CPU_DATA_SIZE, alignment);
        const size_t memfd_size = per_cpu_size * nr_vcpus;
        const size_t slot_size = memfd_size / nr_memslots;
        struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
        pthread_t threads[KVM_MAX_VCPUS];
        struct kvm_vm *vm;
        int memfd, i;

        const struct vm_shape shape = {
                .mode = VM_MODE_DEFAULT,
                .type = KVM_X86_SW_PROTECTED_VM,
        };

        TEST_ASSERT(slot_size * nr_memslots == memfd_size,
                    "The memfd size (0x%lx) needs to be cleanly divisible by the number of memslots (%u)",
                    memfd_size, nr_memslots);
        vm = __vm_create_with_vcpus(shape, nr_vcpus, 0, guest_code, vcpus);

        vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, (1 << KVM_HC_MAP_GPA_RANGE));

        memfd = vm_create_guest_memfd(vm, memfd_size, 0);

        for (i = 0; i < nr_memslots; i++)
                vm_mem_add(vm, src_type, BASE_DATA_GPA + slot_size * i,
                           BASE_DATA_SLOT + i, slot_size / vm->page_size,
                           KVM_MEM_GUEST_MEMFD, memfd, slot_size * i);

        for (i = 0; i < nr_vcpus; i++) {
                uint64_t gpa =  BASE_DATA_GPA + i * per_cpu_size;

                vcpu_args_set(vcpus[i], 1, gpa);

                /*
                 * Map only what is needed so that an out-of-bounds access
                 * results #PF => SHUTDOWN instead of data corruption.
                 */
                virt_map(vm, gpa, gpa, PER_CPU_DATA_SIZE / vm->page_size);

                pthread_create(&threads[i], NULL, __test_mem_conversions, vcpus[i]);
        }

        WRITE_ONCE(run_vcpus, true);

        for (i = 0; i < nr_vcpus; i++)
                pthread_join(threads[i], NULL);

        kvm_vm_free(vm);

        /*
         * Allocate and free memory from the guest_memfd after closing the VM
         * fd.  The guest_memfd is gifted a reference to its owning VM, i.e.
         * should prevent the VM from being fully destroyed until the last
         * reference to the guest_memfd is also put.
         */
        kvm_fallocate(memfd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, memfd_size);
        kvm_fallocate(memfd, FALLOC_FL_KEEP_SIZE, 0, memfd_size);

        close(memfd);
}

static void usage(const char *cmd)
{
        puts("");
        printf("usage: %s [-h] [-m nr_memslots] [-s mem_type] [-n nr_vcpus]\n", cmd);
        puts("");
        backing_src_help("-s");
        puts("");
        puts(" -n: specify the number of vcpus (default: 1)");
        puts("");
        puts(" -m: specify the number of memslots (default: 1)");
        puts("");
}

int main(int argc, char *argv[])
{
        enum vm_mem_backing_src_type src_type = DEFAULT_VM_MEM_SRC;
        uint32_t nr_memslots = 1;
        uint32_t nr_vcpus = 1;
        int opt;

        TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM));

        while ((opt = getopt(argc, argv, "hm:s:n:")) != -1) {
                switch (opt) {
                case 's':
                        src_type = parse_backing_src_type(optarg);
                        break;
                case 'n':
                        nr_vcpus = atoi_positive("nr_vcpus", optarg);
                        break;
                case 'm':
                        nr_memslots = atoi_positive("nr_memslots", optarg);
                        break;
                case 'h':
                default:
                        usage(argv[0]);
                        exit(0);
                }
        }

        test_mem_conversions(src_type, nr_vcpus, nr_memslots);

        return 0;
}