vmx_dirty_log_test.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * KVM dirty page logging test
  4 *
  5 * Copyright (C) 2018, Red Hat, Inc.
  6 */
  7#include <stdio.h>
  8#include <stdlib.h>
  9#include <linux/bitmap.h>
 10#include <linux/bitops.h>
 11
 12#include "test_util.h"
 13#include "kvm_util.h"
 14#include "processor.h"
 15#include "vmx.h"
 16
 17/* The memory slot index to track dirty pages */
 18#define TEST_MEM_SLOT_INDEX		1
 19#define TEST_MEM_PAGES			3
 20
 21/* L1 guest test virtual memory offset */
 22#define GUEST_TEST_MEM			0xc0000000
 23
 24/* L2 guest test virtual memory offset */
 25#define NESTED_TEST_MEM1		0xc0001000
 26#define NESTED_TEST_MEM2		0xc0002000
 27
 28static void l2_guest_code(u64 *a, u64 *b)
 29{
 30	READ_ONCE(*a);
 31	WRITE_ONCE(*a, 1);
 32	GUEST_SYNC(true);
 33	GUEST_SYNC(false);
 34
 35	WRITE_ONCE(*b, 1);
 36	GUEST_SYNC(true);
 37	WRITE_ONCE(*b, 1);
 38	GUEST_SYNC(true);
 39	GUEST_SYNC(false);
 40
 41	/* Exit to L1 and never come back.  */
 42	vmcall();
 43}
 44
 45static void l2_guest_code_ept_enabled(void)
 46{
 47	l2_guest_code((u64 *)NESTED_TEST_MEM1, (u64 *)NESTED_TEST_MEM2);
 48}
 49
 50static void l2_guest_code_ept_disabled(void)
 51{
 52	/* Access the same L1 GPAs as l2_guest_code_ept_enabled() */
 53	l2_guest_code((u64 *)GUEST_TEST_MEM, (u64 *)GUEST_TEST_MEM);
 54}
 55
 56void l1_guest_code(struct vmx_pages *vmx)
 57{
 58#define L2_GUEST_STACK_SIZE 64
 59	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 60	void *l2_rip;
 61
 62	GUEST_ASSERT(vmx->vmcs_gpa);
 63	GUEST_ASSERT(prepare_for_vmx_operation(vmx));
 64	GUEST_ASSERT(load_vmcs(vmx));
 65
 66	if (vmx->eptp_gpa)
 67		l2_rip = l2_guest_code_ept_enabled;
 68	else
 69		l2_rip = l2_guest_code_ept_disabled;
 70
 71	prepare_vmcs(vmx, l2_rip, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 72
 73	GUEST_SYNC(false);
 74	GUEST_ASSERT(!vmlaunch());
 75	GUEST_SYNC(false);
 76	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 77	GUEST_DONE();
 78}
 79
 80static void test_vmx_dirty_log(bool enable_ept)
 81{
 82	vm_vaddr_t vmx_pages_gva = 0;
 83	struct vmx_pages *vmx;
 84	unsigned long *bmap;
 85	uint64_t *host_test_mem;
 86
 87	struct kvm_vcpu *vcpu;
 88	struct kvm_vm *vm;
 89	struct ucall uc;
 90	bool done = false;
 91
 92	pr_info("Nested EPT: %s\n", enable_ept ? "enabled" : "disabled");
 93
 94	/* Create VM */
 95	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
 96	vmx = vcpu_alloc_vmx(vm, &vmx_pages_gva);
 97	vcpu_args_set(vcpu, 1, vmx_pages_gva);
 98
 99	/* Add an extra memory slot for testing dirty logging */
100	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
101				    GUEST_TEST_MEM,
102				    TEST_MEM_SLOT_INDEX,
103				    TEST_MEM_PAGES,
104				    KVM_MEM_LOG_DIRTY_PAGES);
105
106	/*
107	 * Add an identity map for GVA range [0xc0000000, 0xc0002000).  This
108	 * affects both L1 and L2.  However...
109	 */
110	virt_map(vm, GUEST_TEST_MEM, GUEST_TEST_MEM, TEST_MEM_PAGES);
111
112	/*
113	 * ... pages in the L2 GPA range [0xc0001000, 0xc0003000) will map to
114	 * 0xc0000000.
115	 *
116	 * Note that prepare_eptp should be called only L1's GPA map is done,
117	 * meaning after the last call to virt_map.
118	 *
119	 * When EPT is disabled, the L2 guest code will still access the same L1
120	 * GPAs as the EPT enabled case.
121	 */
122	if (enable_ept) {
123		prepare_eptp(vmx, vm);
124		nested_map_memslot(vmx, vm, 0);
125		nested_map(vmx, vm, NESTED_TEST_MEM1, GUEST_TEST_MEM, PAGE_SIZE);
126		nested_map(vmx, vm, NESTED_TEST_MEM2, GUEST_TEST_MEM, PAGE_SIZE);
127	}
128
129	bmap = bitmap_zalloc(TEST_MEM_PAGES);
130	host_test_mem = addr_gpa2hva(vm, GUEST_TEST_MEM);
131
132	while (!done) {
133		memset(host_test_mem, 0xaa, TEST_MEM_PAGES * PAGE_SIZE);
134		vcpu_run(vcpu);
135		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
136
137		switch (get_ucall(vcpu, &uc)) {
138		case UCALL_ABORT:
139			REPORT_GUEST_ASSERT(uc);
140			/* NOT REACHED */
141		case UCALL_SYNC:
142			/*
143			 * The nested guest wrote at offset 0x1000 in the memslot, but the
144			 * dirty bitmap must be filled in according to L1 GPA, not L2.
145			 */
146			kvm_vm_get_dirty_log(vm, TEST_MEM_SLOT_INDEX, bmap);
147			if (uc.args[1]) {
148				TEST_ASSERT(test_bit(0, bmap), "Page 0 incorrectly reported clean");
149				TEST_ASSERT(host_test_mem[0] == 1, "Page 0 not written by guest");
150			} else {
151				TEST_ASSERT(!test_bit(0, bmap), "Page 0 incorrectly reported dirty");
152				TEST_ASSERT(host_test_mem[0] == 0xaaaaaaaaaaaaaaaaULL, "Page 0 written by guest");
153			}
154
155			TEST_ASSERT(!test_bit(1, bmap), "Page 1 incorrectly reported dirty");
156			TEST_ASSERT(host_test_mem[PAGE_SIZE / 8] == 0xaaaaaaaaaaaaaaaaULL, "Page 1 written by guest");
157			TEST_ASSERT(!test_bit(2, bmap), "Page 2 incorrectly reported dirty");
158			TEST_ASSERT(host_test_mem[PAGE_SIZE*2 / 8] == 0xaaaaaaaaaaaaaaaaULL, "Page 2 written by guest");
159			break;
160		case UCALL_DONE:
161			done = true;
162			break;
163		default:
164			TEST_FAIL("Unknown ucall %lu", uc.cmd);
165		}
166	}
167}
168
169int main(int argc, char *argv[])
170{
171	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
172
173	test_vmx_dirty_log(/*enable_ept=*/false);
174
175	if (kvm_cpu_has_ept())
176		test_vmx_dirty_log(/*enable_ept=*/true);
177
178	return 0;
179}