1 // SPDX-License-Identifier: GPL-2.0-only
2 #define _GNU_SOURCE /* for program_invocation_short_name */
3 #include <fcntl.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <sys/ioctl.h>
8 
9 #include "apic.h"
10 #include "kvm_util.h"
11 #include "processor.h"
12 #include "test_util.h"
13 
14 struct xapic_vcpu {
15 	struct kvm_vcpu *vcpu;
16 	bool is_x2apic;
17 };
18 
19 static void xapic_guest_code(void)
20 {
21 	asm volatile("cli");
22 
23 	xapic_enable();
24 
25 	while (1) {
26 		uint64_t val = (u64)xapic_read_reg(APIC_IRR) |
27 			       (u64)xapic_read_reg(APIC_IRR + 0x10) << 32;
28 
29 		xapic_write_reg(APIC_ICR2, val >> 32);
30 		xapic_write_reg(APIC_ICR, val);
31 		GUEST_SYNC(val);
32 	}
33 }
34 
35 static void x2apic_guest_code(void)
36 {
37 	asm volatile("cli");
38 
39 	x2apic_enable();
40 
41 	do {
42 		uint64_t val = x2apic_read_reg(APIC_IRR) |
43 			       x2apic_read_reg(APIC_IRR + 0x10) << 32;
44 
45 		x2apic_write_reg(APIC_ICR, val);
46 		GUEST_SYNC(val);
47 	} while (1);
48 }
49 
50 static void ____test_icr(struct xapic_vcpu *x, uint64_t val)
51 {
52 	struct kvm_vcpu *vcpu = x->vcpu;
53 	struct kvm_lapic_state xapic;
54 	struct ucall uc;
55 	uint64_t icr;
56 
57 	/*
58 	 * Tell the guest what ICR value to write.  Use the IRR to pass info,
59 	 * all bits are valid and should not be modified by KVM (ignoring the
60 	 * fact that vectors 0-15 are technically illegal).
61 	 */
62 	vcpu_ioctl(vcpu, KVM_GET_LAPIC, &xapic);
63 	*((u32 *)&xapic.regs[APIC_IRR]) = val;
64 	*((u32 *)&xapic.regs[APIC_IRR + 0x10]) = val >> 32;
65 	vcpu_ioctl(vcpu, KVM_SET_LAPIC, &xapic);
66 
67 	vcpu_run(vcpu);
68 	TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_SYNC);
69 	TEST_ASSERT_EQ(uc.args[1], val);
70 
71 	vcpu_ioctl(vcpu, KVM_GET_LAPIC, &xapic);
72 	icr = (u64)(*((u32 *)&xapic.regs[APIC_ICR])) |
73 	      (u64)(*((u32 *)&xapic.regs[APIC_ICR2])) << 32;
74 	if (!x->is_x2apic) {
75 		val &= (-1u | (0xffull << (32 + 24)));
76 		TEST_ASSERT_EQ(icr, val & ~APIC_ICR_BUSY);
77 	} else {
78 		TEST_ASSERT_EQ(icr & ~APIC_ICR_BUSY, val & ~APIC_ICR_BUSY);
79 	}
80 }
81 
82 #define X2APIC_RSVED_BITS_MASK  (GENMASK_ULL(31,20) | \
83 				 GENMASK_ULL(17,16) | \
84 				 GENMASK_ULL(13,13))
85 
86 static void __test_icr(struct xapic_vcpu *x, uint64_t val)
87 {
88 	if (x->is_x2apic) {
89 		/* Hardware writing vICR register requires reserved bits 31:20,
90 		 * 17:16 and 13 kept as zero to avoid #GP exception. Data value
91 		 * written to vICR should mask out those bits above.
92 		 */
93 		val &= ~X2APIC_RSVED_BITS_MASK;
94 	}
95 	____test_icr(x, val | APIC_ICR_BUSY);
96 	____test_icr(x, val & ~(u64)APIC_ICR_BUSY);
97 }
98 
99 static void test_icr(struct xapic_vcpu *x)
100 {
101 	struct kvm_vcpu *vcpu = x->vcpu;
102 	uint64_t icr, i, j;
103 
104 	icr = APIC_DEST_SELF | APIC_INT_ASSERT | APIC_DM_FIXED;
105 	for (i = 0; i <= 0xff; i++)
106 		__test_icr(x, icr | i);
107 
108 	icr = APIC_INT_ASSERT | APIC_DM_FIXED;
109 	for (i = 0; i <= 0xff; i++)
110 		__test_icr(x, icr | i);
111 
112 	/*
113 	 * Send all flavors of IPIs to non-existent vCPUs.  TODO: use number of
114 	 * vCPUs, not vcpu.id + 1.  Arbitrarily use vector 0xff.
115 	 */
116 	icr = APIC_INT_ASSERT | 0xff;
117 	for (i = 0; i < 0xff; i++) {
118 		if (i == vcpu->id)
119 			continue;
120 		for (j = 0; j < 8; j++)
121 			__test_icr(x, i << (32 + 24) | icr | (j << 8));
122 	}
123 
124 	/* And again with a shorthand destination for all types of IPIs. */
125 	icr = APIC_DEST_ALLBUT | APIC_INT_ASSERT;
126 	for (i = 0; i < 8; i++)
127 		__test_icr(x, icr | (i << 8));
128 
129 	/* And a few garbage value, just make sure it's an IRQ (blocked). */
130 	__test_icr(x, 0xa5a5a5a5a5a5a5a5 & ~APIC_DM_FIXED_MASK);
131 	__test_icr(x, 0x5a5a5a5a5a5a5a5a & ~APIC_DM_FIXED_MASK);
132 	__test_icr(x, -1ull & ~APIC_DM_FIXED_MASK);
133 }
134 
135 static void __test_apic_id(struct kvm_vcpu *vcpu, uint64_t apic_base)
136 {
137 	uint32_t apic_id, expected;
138 	struct kvm_lapic_state xapic;
139 
140 	vcpu_set_msr(vcpu, MSR_IA32_APICBASE, apic_base);
141 
142 	vcpu_ioctl(vcpu, KVM_GET_LAPIC, &xapic);
143 
144 	expected = apic_base & X2APIC_ENABLE ? vcpu->id : vcpu->id << 24;
145 	apic_id = *((u32 *)&xapic.regs[APIC_ID]);
146 
147 	TEST_ASSERT(apic_id == expected,
148 		    "APIC_ID not set back to %s format; wanted = %x, got = %x",
149 		    (apic_base & X2APIC_ENABLE) ? "x2APIC" : "xAPIC",
150 		    expected, apic_id);
151 }
152 
153 /*
154  * Verify that KVM switches the APIC_ID between xAPIC and x2APIC when userspace
155  * stuffs MSR_IA32_APICBASE.  Setting the APIC_ID when x2APIC is enabled and
156  * when the APIC transitions for DISABLED to ENABLED is architectural behavior
157  * (on Intel), whereas the x2APIC => xAPIC transition behavior is KVM ABI since
158  * attempted to transition from x2APIC to xAPIC without disabling the APIC is
159  * architecturally disallowed.
160  */
161 static void test_apic_id(void)
162 {
163 	const uint32_t NR_VCPUS = 3;
164 	struct kvm_vcpu *vcpus[NR_VCPUS];
165 	uint64_t apic_base;
166 	struct kvm_vm *vm;
167 	int i;
168 
169 	vm = vm_create_with_vcpus(NR_VCPUS, NULL, vcpus);
170 	vm_enable_cap(vm, KVM_CAP_X2APIC_API, KVM_X2APIC_API_USE_32BIT_IDS);
171 
172 	for (i = 0; i < NR_VCPUS; i++) {
173 		apic_base = vcpu_get_msr(vcpus[i], MSR_IA32_APICBASE);
174 
175 		TEST_ASSERT(apic_base & MSR_IA32_APICBASE_ENABLE,
176 			    "APIC not in ENABLED state at vCPU RESET");
177 		TEST_ASSERT(!(apic_base & X2APIC_ENABLE),
178 			    "APIC not in xAPIC mode at vCPU RESET");
179 
180 		__test_apic_id(vcpus[i], apic_base);
181 		__test_apic_id(vcpus[i], apic_base | X2APIC_ENABLE);
182 		__test_apic_id(vcpus[i], apic_base);
183 	}
184 
185 	kvm_vm_free(vm);
186 }
187 
188 int main(int argc, char *argv[])
189 {
190 	struct xapic_vcpu x = {
191 		.vcpu = NULL,
192 		.is_x2apic = true,
193 	};
194 	struct kvm_vm *vm;
195 
196 	vm = vm_create_with_one_vcpu(&x.vcpu, x2apic_guest_code);
197 	test_icr(&x);
198 	kvm_vm_free(vm);
199 
200 	/*
201 	 * Use a second VM for the xAPIC test so that x2APIC can be hidden from
202 	 * the guest in order to test AVIC.  KVM disallows changing CPUID after
203 	 * KVM_RUN and AVIC is disabled if _any_ vCPU is allowed to use x2APIC.
204 	 */
205 	vm = vm_create_with_one_vcpu(&x.vcpu, xapic_guest_code);
206 	x.is_x2apic = false;
207 
208 	vcpu_clear_cpuid_feature(x.vcpu, X86_FEATURE_X2APIC);
209 
210 	virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
211 	test_icr(&x);
212 	kvm_vm_free(vm);
213 
214 	test_apic_id();
215 }
216