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 <linux/fs.h> 8 9 #include "test_util.h" 10 #include "kvm_syscalls.h" 11 #include "kvm_util.h" 12 #include "kselftest.h" 13 #include "ucall_common.h" 14 15 static void set_storage_key(void *addr, u8 skey) 16 { 17 asm volatile("sske %0,%1" : : "d" (skey), "a" (addr)); 18 } 19 20 static void guest_code(void) 21 { 22 /* Issue some storage key instruction. */ 23 set_storage_key((void *)0, 0x98); 24 GUEST_DONE(); 25 } 26 27 /* 28 * Returns 1 if the shared zeropage is mapped, 0 if something else is mapped. 29 * Returns < 0 on error or if nothing is mapped. 30 */ 31 static int maps_shared_zeropage(int pagemap_fd, void *addr) 32 { 33 struct page_region region; 34 struct pm_scan_arg arg = { 35 .start = (uintptr_t)addr, 36 .end = (uintptr_t)addr + 4096, 37 .vec = (uintptr_t)®ion, 38 .vec_len = 1, 39 .size = sizeof(struct pm_scan_arg), 40 .category_mask = PAGE_IS_PFNZERO, 41 .category_anyof_mask = PAGE_IS_PRESENT, 42 .return_mask = PAGE_IS_PFNZERO, 43 }; 44 return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg); 45 } 46 47 int main(int argc, char *argv[]) 48 { 49 char *mem, *page0, *page1, *page2, tmp; 50 const size_t pagesize = getpagesize(); 51 struct kvm_vcpu *vcpu; 52 struct kvm_vm *vm; 53 struct ucall uc; 54 int pagemap_fd; 55 56 ksft_print_header(); 57 ksft_set_plan(3); 58 59 /* 60 * We'll use memory that is not mapped into the VM for simplicity. 61 * Shared zeropages are enabled/disabled per-process. 62 */ 63 mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0); 64 TEST_ASSERT(mem != MAP_FAILED, "mmap() failed"); 65 66 /* Disable THP. Ignore errors on older kernels. */ 67 madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE); 68 69 page0 = mem; 70 page1 = page0 + pagesize; 71 page2 = page1 + pagesize; 72 73 /* Can we even detect shared zeropages? */ 74 pagemap_fd = open("/proc/self/pagemap", O_RDONLY); 75 TEST_REQUIRE(pagemap_fd >= 0); 76 77 tmp = *page0; 78 asm volatile("" : "+r" (tmp)); 79 TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1); 80 81 vm = vm_create_with_one_vcpu(&vcpu, guest_code); 82 83 /* Verify that we get the shared zeropage after VM creation. */ 84 tmp = *page1; 85 asm volatile("" : "+r" (tmp)); 86 ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1, 87 "Shared zeropages should be enabled\n"); 88 89 /* 90 * Let our VM execute a storage key instruction that should 91 * unshare all shared zeropages. 92 */ 93 vcpu_run(vcpu); 94 get_ucall(vcpu, &uc); 95 TEST_ASSERT_EQ(uc.cmd, UCALL_DONE); 96 97 /* Verify that we don't have a shared zeropage anymore. */ 98 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1), 99 "Shared zeropage should be gone\n"); 100 101 /* Verify that we don't get any new shared zeropages. */ 102 tmp = *page2; 103 asm volatile("" : "+r" (tmp)); 104 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2), 105 "Shared zeropages should be disabled\n"); 106 107 kvm_vm_free(vm); 108 109 ksft_finished(); 110 } 111