// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Test shared zeropage handling (with/without storage keys)
 *
 * Copyright (C) 2024, Red Hat, Inc.
 */
#include <sys/mman.h>

#include <linux/fs.h>

#include "test_util.h"
#include "kvm_util.h"
#include "kselftest.h"
#include "ucall_common.h"

static void set_storage_key(void *addr, uint8_t skey)
{
        asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));
}

static void guest_code(void)
{
        /* Issue some storage key instruction. */
        set_storage_key((void *)0, 0x98);
        GUEST_DONE();
}

/*
 * Returns 1 if the shared zeropage is mapped, 0 if something else is mapped.
 * Returns < 0 on error or if nothing is mapped.
 */
static int maps_shared_zeropage(int pagemap_fd, void *addr)
{
        struct page_region region;
        struct pm_scan_arg arg = {
                .start = (uintptr_t)addr,
                .end = (uintptr_t)addr + 4096,
                .vec = (uintptr_t)&region,
                .vec_len = 1,
                .size = sizeof(struct pm_scan_arg),
                .category_mask = PAGE_IS_PFNZERO,
                .category_anyof_mask = PAGE_IS_PRESENT,
                .return_mask = PAGE_IS_PFNZERO,
        };
        return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);
}

int main(int argc, char *argv[])
{
        char *mem, *page0, *page1, *page2, tmp;
        const size_t pagesize = getpagesize();
        struct kvm_vcpu *vcpu;
        struct kvm_vm *vm;
        struct ucall uc;
        int pagemap_fd;

        ksft_print_header();
        ksft_set_plan(3);

        /*
         * We'll use memory that is not mapped into the VM for simplicity.
         * Shared zeropages are enabled/disabled per-process.
         */
        mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
        TEST_ASSERT(mem != MAP_FAILED, "mmap() failed");

        /* Disable THP. Ignore errors on older kernels. */
        madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE);

        page0 = mem;
        page1 = page0 + pagesize;
        page2 = page1 + pagesize;

        /* Can we even detect shared zeropages? */
        pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
        TEST_REQUIRE(pagemap_fd >= 0);

        tmp = *page0;
        asm volatile("" : "+r" (tmp));
        TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1);

        vm = vm_create_with_one_vcpu(&vcpu, guest_code);

        /* Verify that we get the shared zeropage after VM creation. */
        tmp = *page1;
        asm volatile("" : "+r" (tmp));
        ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1,
                         "Shared zeropages should be enabled\n");

        /*
         * Let our VM execute a storage key instruction that should
         * unshare all shared zeropages.
         */
        vcpu_run(vcpu);
        get_ucall(vcpu, &uc);
        TEST_ASSERT_EQ(uc.cmd, UCALL_DONE);

        /* Verify that we don't have a shared zeropage anymore. */
        ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1),
                         "Shared zeropage should be gone\n");

        /* Verify that we don't get any new shared zeropages. */
        tmp = *page2;
        asm volatile("" : "+r" (tmp));
        ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2),
                         "Shared zeropages should be disabled\n");

        kvm_vm_free(vm);

        ksft_finished();
}