1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2012,2013 - ARM Ltd
4 * Author: Marc Zyngier <marc.zyngier@arm.com>
5 *
6 * Derived from arch/arm/kvm/handle_exit.c:
7 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
8 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
9 */
10
11 #include <linux/kvm.h>
12 #include <linux/kvm_host.h>
13
14 #include <asm/esr.h>
15 #include <asm/exception.h>
16 #include <asm/kvm_asm.h>
17 #include <asm/kvm_emulate.h>
18 #include <asm/kvm_mmu.h>
19 #include <asm/debug-monitors.h>
20 #include <asm/traps.h>
21
22 #include <kvm/arm_hypercalls.h>
23
24 #define CREATE_TRACE_POINTS
25 #include "trace_handle_exit.h"
26
27 typedef int (*exit_handle_fn)(struct kvm_vcpu *);
28
kvm_handle_guest_serror(struct kvm_vcpu * vcpu,u32 esr)29 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr)
30 {
31 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr))
32 kvm_inject_vabt(vcpu);
33 }
34
handle_hvc(struct kvm_vcpu * vcpu)35 static int handle_hvc(struct kvm_vcpu *vcpu)
36 {
37 int ret;
38
39 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
40 kvm_vcpu_hvc_get_imm(vcpu));
41 vcpu->stat.hvc_exit_stat++;
42
43 ret = kvm_hvc_call_handler(vcpu);
44 if (ret < 0) {
45 vcpu_set_reg(vcpu, 0, ~0UL);
46 return 1;
47 }
48
49 return ret;
50 }
51
handle_smc(struct kvm_vcpu * vcpu)52 static int handle_smc(struct kvm_vcpu *vcpu)
53 {
54 /*
55 * "If an SMC instruction executed at Non-secure EL1 is
56 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
57 * Trap exception, not a Secure Monitor Call exception [...]"
58 *
59 * We need to advance the PC after the trap, as it would
60 * otherwise return to the same address...
61 */
62 vcpu_set_reg(vcpu, 0, ~0UL);
63 kvm_incr_pc(vcpu);
64 return 1;
65 }
66
67 /*
68 * Guest access to FP/ASIMD registers are routed to this handler only
69 * when the system doesn't support FP/ASIMD.
70 */
handle_no_fpsimd(struct kvm_vcpu * vcpu)71 static int handle_no_fpsimd(struct kvm_vcpu *vcpu)
72 {
73 kvm_inject_undefined(vcpu);
74 return 1;
75 }
76
77 /**
78 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
79 * instruction executed by a guest
80 *
81 * @vcpu: the vcpu pointer
82 *
83 * WFE: Yield the CPU and come back to this vcpu when the scheduler
84 * decides to.
85 * WFI: Simply call kvm_vcpu_block(), which will halt execution of
86 * world-switches and schedule other host processes until there is an
87 * incoming IRQ or FIQ to the VM.
88 */
kvm_handle_wfx(struct kvm_vcpu * vcpu)89 static int kvm_handle_wfx(struct kvm_vcpu *vcpu)
90 {
91 if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
92 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
93 vcpu->stat.wfe_exit_stat++;
94 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
95 } else {
96 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
97 vcpu->stat.wfi_exit_stat++;
98 kvm_vcpu_block(vcpu);
99 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
100 }
101
102 kvm_incr_pc(vcpu);
103
104 return 1;
105 }
106
107 /**
108 * kvm_handle_guest_debug - handle a debug exception instruction
109 *
110 * @vcpu: the vcpu pointer
111 *
112 * We route all debug exceptions through the same handler. If both the
113 * guest and host are using the same debug facilities it will be up to
114 * userspace to re-inject the correct exception for guest delivery.
115 *
116 * @return: 0 (while setting vcpu->run->exit_reason), -1 for error
117 */
kvm_handle_guest_debug(struct kvm_vcpu * vcpu)118 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
119 {
120 struct kvm_run *run = vcpu->run;
121 u32 esr = kvm_vcpu_get_esr(vcpu);
122 int ret = 0;
123
124 run->exit_reason = KVM_EXIT_DEBUG;
125 run->debug.arch.hsr = esr;
126
127 switch (ESR_ELx_EC(esr)) {
128 case ESR_ELx_EC_WATCHPT_LOW:
129 run->debug.arch.far = vcpu->arch.fault.far_el2;
130 fallthrough;
131 case ESR_ELx_EC_SOFTSTP_LOW:
132 case ESR_ELx_EC_BREAKPT_LOW:
133 case ESR_ELx_EC_BKPT32:
134 case ESR_ELx_EC_BRK64:
135 break;
136 default:
137 kvm_err("%s: un-handled case esr: %#08x\n",
138 __func__, (unsigned int) esr);
139 ret = -1;
140 break;
141 }
142
143 return ret;
144 }
145
kvm_handle_unknown_ec(struct kvm_vcpu * vcpu)146 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
147 {
148 u32 esr = kvm_vcpu_get_esr(vcpu);
149
150 kvm_pr_unimpl("Unknown exception class: esr: %#08x -- %s\n",
151 esr, esr_get_class_string(esr));
152
153 kvm_inject_undefined(vcpu);
154 return 1;
155 }
156
handle_sve(struct kvm_vcpu * vcpu)157 static int handle_sve(struct kvm_vcpu *vcpu)
158 {
159 /* Until SVE is supported for guests: */
160 kvm_inject_undefined(vcpu);
161 return 1;
162 }
163
164 /*
165 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
166 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all
167 * that we can do is give the guest an UNDEF.
168 */
kvm_handle_ptrauth(struct kvm_vcpu * vcpu)169 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
170 {
171 kvm_inject_undefined(vcpu);
172 return 1;
173 }
174
175 static exit_handle_fn arm_exit_handlers[] = {
176 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
177 [ESR_ELx_EC_WFx] = kvm_handle_wfx,
178 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
179 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
180 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32,
181 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store,
182 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64,
183 [ESR_ELx_EC_HVC32] = handle_hvc,
184 [ESR_ELx_EC_SMC32] = handle_smc,
185 [ESR_ELx_EC_HVC64] = handle_hvc,
186 [ESR_ELx_EC_SMC64] = handle_smc,
187 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
188 [ESR_ELx_EC_SVE] = handle_sve,
189 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
190 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
191 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
192 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
193 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
194 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
195 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
196 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
197 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth,
198 };
199
kvm_get_exit_handler(struct kvm_vcpu * vcpu)200 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
201 {
202 u32 esr = kvm_vcpu_get_esr(vcpu);
203 u8 esr_ec = ESR_ELx_EC(esr);
204
205 return arm_exit_handlers[esr_ec];
206 }
207
208 /*
209 * We may be single-stepping an emulated instruction. If the emulation
210 * has been completed in the kernel, we can return to userspace with a
211 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
212 * emulation first.
213 */
handle_trap_exceptions(struct kvm_vcpu * vcpu)214 static int handle_trap_exceptions(struct kvm_vcpu *vcpu)
215 {
216 int handled;
217
218 /*
219 * See ARM ARM B1.14.1: "Hyp traps on instructions
220 * that fail their condition code check"
221 */
222 if (!kvm_condition_valid(vcpu)) {
223 kvm_incr_pc(vcpu);
224 handled = 1;
225 } else {
226 exit_handle_fn exit_handler;
227
228 exit_handler = kvm_get_exit_handler(vcpu);
229 handled = exit_handler(vcpu);
230 }
231
232 return handled;
233 }
234
235 /*
236 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
237 * proper exit to userspace.
238 */
handle_exit(struct kvm_vcpu * vcpu,int exception_index)239 int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
240 {
241 struct kvm_run *run = vcpu->run;
242
243 if (ARM_SERROR_PENDING(exception_index)) {
244 /*
245 * The SError is handled by handle_exit_early(). If the guest
246 * survives it will re-execute the original instruction.
247 */
248 return 1;
249 }
250
251 exception_index = ARM_EXCEPTION_CODE(exception_index);
252
253 switch (exception_index) {
254 case ARM_EXCEPTION_IRQ:
255 return 1;
256 case ARM_EXCEPTION_EL1_SERROR:
257 return 1;
258 case ARM_EXCEPTION_TRAP:
259 return handle_trap_exceptions(vcpu);
260 case ARM_EXCEPTION_HYP_GONE:
261 /*
262 * EL2 has been reset to the hyp-stub. This happens when a guest
263 * is pre-empted by kvm_reboot()'s shutdown call.
264 */
265 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
266 return 0;
267 case ARM_EXCEPTION_IL:
268 /*
269 * We attempted an illegal exception return. Guest state must
270 * have been corrupted somehow. Give up.
271 */
272 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
273 return -EINVAL;
274 default:
275 kvm_pr_unimpl("Unsupported exception type: %d",
276 exception_index);
277 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
278 return 0;
279 }
280 }
281
282 /* For exit types that need handling before we can be preempted */
handle_exit_early(struct kvm_vcpu * vcpu,int exception_index)283 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index)
284 {
285 if (ARM_SERROR_PENDING(exception_index)) {
286 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) {
287 u64 disr = kvm_vcpu_get_disr(vcpu);
288
289 kvm_handle_guest_serror(vcpu, disr_to_esr(disr));
290 } else {
291 kvm_inject_vabt(vcpu);
292 }
293
294 return;
295 }
296
297 exception_index = ARM_EXCEPTION_CODE(exception_index);
298
299 if (exception_index == ARM_EXCEPTION_EL1_SERROR)
300 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu));
301 }
302