1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Test shared zeropage handling (with/without storage keys)
4 *
5 * Copyright (C) 2024, Red Hat, Inc.
6 */
7 #include <sys/mman.h>
8
9 #include <linux/fs.h>
10
11 #include "test_util.h"
12 #include "kvm_util.h"
13 #include "kselftest.h"
14 #include "ucall_common.h"
15
16 static void set_storage_key(void *addr, uint8_t skey)
17 {
18 asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));
19 }
20
21 static void guest_code(void)
22 {
23 /* Issue some storage key instruction. */
24 set_storage_key((void *)0, 0x98);
25 GUEST_DONE();
26 }
27
28 /*
29 * Returns 1 if the shared zeropage is mapped, 0 if something else is mapped.
30 * Returns < 0 on error or if nothing is mapped.
31 */
32 static int maps_shared_zeropage(int pagemap_fd, void *addr)
33 {
34 struct page_region region;
35 struct pm_scan_arg arg = {
36 .start = (uintptr_t)addr,
37 .end = (uintptr_t)addr + 4096,
38 .vec = (uintptr_t)®ion,
39 .vec_len = 1,
40 .size = sizeof(struct pm_scan_arg),
41 .category_mask = PAGE_IS_PFNZERO,
42 .category_anyof_mask = PAGE_IS_PRESENT,
43 .return_mask = PAGE_IS_PFNZERO,
44 };
45 return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);
46 }
47
48 int main(int argc, char *argv[])
49 {
50 char *mem, *page0, *page1, *page2, tmp;
51 const size_t pagesize = getpagesize();
52 struct kvm_vcpu *vcpu;
53 struct kvm_vm *vm;
54 struct ucall uc;
55 int pagemap_fd;
56
57 ksft_print_header();
58 ksft_set_plan(3);
59
60 /*
61 * We'll use memory that is not mapped into the VM for simplicity.
62 * Shared zeropages are enabled/disabled per-process.
63 */
64 mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
65 TEST_ASSERT(mem != MAP_FAILED, "mmap() failed");
66
67 /* Disable THP. Ignore errors on older kernels. */
68 madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE);
69
70 page0 = mem;
71 page1 = page0 + pagesize;
72 page2 = page1 + pagesize;
73
74 /* Can we even detect shared zeropages? */
75 pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
76 TEST_REQUIRE(pagemap_fd >= 0);
77
78 tmp = *page0;
79 asm volatile("" : "+r" (tmp));
80 TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1);
81
82 vm = vm_create_with_one_vcpu(&vcpu, guest_code);
83
84 /* Verify that we get the shared zeropage after VM creation. */
85 tmp = *page1;
86 asm volatile("" : "+r" (tmp));
87 ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1,
88 "Shared zeropages should be enabled\n");
89
90 /*
91 * Let our VM execute a storage key instruction that should
92 * unshare all shared zeropages.
93 */
94 vcpu_run(vcpu);
95 get_ucall(vcpu, &uc);
96 TEST_ASSERT_EQ(uc.cmd, UCALL_DONE);
97
98 /* Verify that we don't have a shared zeropage anymore. */
99 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1),
100 "Shared zeropage should be gone\n");
101
102 /* Verify that we don't get any new shared zeropages. */
103 tmp = *page2;
104 asm volatile("" : "+r" (tmp));
105 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2),
106 "Shared zeropages should be disabled\n");
107
108 kvm_vm_free(vm);
109
110 ksft_finished();
111 }
112
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