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_coproc.h>
18 #include <asm/kvm_emulate.h>
19 #include <asm/kvm_mmu.h>
20 #include <asm/debug-monitors.h>
21 #include <asm/traps.h>
22
23 #include <kvm/arm_hypercalls.h>
24
25 #define CREATE_TRACE_POINTS
26 #include "trace_handle_exit.h"
27
28 typedef int (*exit_handle_fn)(struct kvm_vcpu *);
29
kvm_handle_guest_serror(struct kvm_vcpu * vcpu,u32 esr)30 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr)
31 {
32 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr))
33 kvm_inject_vabt(vcpu);
34 }
35
handle_hvc(struct kvm_vcpu * vcpu)36 static int handle_hvc(struct kvm_vcpu *vcpu)
37 {
38 int ret;
39
40 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
41 kvm_vcpu_hvc_get_imm(vcpu));
42 vcpu->stat.hvc_exit_stat++;
43
44 ret = kvm_hvc_call_handler(vcpu);
45 if (ret < 0) {
46 vcpu_set_reg(vcpu, 0, ~0UL);
47 return 1;
48 }
49
50 return ret;
51 }
52
handle_smc(struct kvm_vcpu * vcpu)53 static int handle_smc(struct kvm_vcpu *vcpu)
54 {
55 /*
56 * "If an SMC instruction executed at Non-secure EL1 is
57 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
58 * Trap exception, not a Secure Monitor Call exception [...]"
59 *
60 * We need to advance the PC after the trap, as it would
61 * otherwise return to the same address...
62 */
63 vcpu_set_reg(vcpu, 0, ~0UL);
64 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
65 return 1;
66 }
67
68 /*
69 * Guest access to FP/ASIMD registers are routed to this handler only
70 * when the system doesn't support FP/ASIMD.
71 */
handle_no_fpsimd(struct kvm_vcpu * vcpu)72 static int handle_no_fpsimd(struct kvm_vcpu *vcpu)
73 {
74 kvm_inject_undefined(vcpu);
75 return 1;
76 }
77
78 /**
79 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
80 * instruction executed by a guest
81 *
82 * @vcpu: the vcpu pointer
83 *
84 * WFE: Yield the CPU and come back to this vcpu when the scheduler
85 * decides to.
86 * WFI: Simply call kvm_vcpu_block(), which will halt execution of
87 * world-switches and schedule other host processes until there is an
88 * incoming IRQ or FIQ to the VM.
89 */
kvm_handle_wfx(struct kvm_vcpu * vcpu)90 static int kvm_handle_wfx(struct kvm_vcpu *vcpu)
91 {
92 if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
93 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
94 vcpu->stat.wfe_exit_stat++;
95 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
96 } else {
97 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
98 vcpu->stat.wfi_exit_stat++;
99 kvm_vcpu_block(vcpu);
100 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
101 }
102
103 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
104
105 return 1;
106 }
107
108 /**
109 * kvm_handle_guest_debug - handle a debug exception instruction
110 *
111 * @vcpu: the vcpu pointer
112 *
113 * We route all debug exceptions through the same handler. If both the
114 * guest and host are using the same debug facilities it will be up to
115 * userspace to re-inject the correct exception for guest delivery.
116 *
117 * @return: 0 (while setting vcpu->run->exit_reason), -1 for error
118 */
kvm_handle_guest_debug(struct kvm_vcpu * vcpu)119 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
120 {
121 struct kvm_run *run = vcpu->run;
122 u32 esr = kvm_vcpu_get_esr(vcpu);
123 int ret = 0;
124
125 run->exit_reason = KVM_EXIT_DEBUG;
126 run->debug.arch.hsr = esr;
127
128 switch (ESR_ELx_EC(esr)) {
129 case ESR_ELx_EC_WATCHPT_LOW:
130 run->debug.arch.far = vcpu->arch.fault.far_el2;
131 fallthrough;
132 case ESR_ELx_EC_SOFTSTP_LOW:
133 case ESR_ELx_EC_BREAKPT_LOW:
134 case ESR_ELx_EC_BKPT32:
135 case ESR_ELx_EC_BRK64:
136 break;
137 default:
138 kvm_err("%s: un-handled case esr: %#08x\n",
139 __func__, (unsigned int) esr);
140 ret = -1;
141 break;
142 }
143
144 return ret;
145 }
146
kvm_handle_unknown_ec(struct kvm_vcpu * vcpu)147 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
148 {
149 u32 esr = kvm_vcpu_get_esr(vcpu);
150
151 kvm_pr_unimpl("Unknown exception class: esr: %#08x -- %s\n",
152 esr, esr_get_class_string(esr));
153
154 kvm_inject_undefined(vcpu);
155 return 1;
156 }
157
handle_sve(struct kvm_vcpu * vcpu)158 static int handle_sve(struct kvm_vcpu *vcpu)
159 {
160 /* Until SVE is supported for guests: */
161 kvm_inject_undefined(vcpu);
162 return 1;
163 }
164
165 /*
166 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
167 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all
168 * that we can do is give the guest an UNDEF.
169 */
kvm_handle_ptrauth(struct kvm_vcpu * vcpu)170 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
171 {
172 kvm_inject_undefined(vcpu);
173 return 1;
174 }
175
176 static exit_handle_fn arm_exit_handlers[] = {
177 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
178 [ESR_ELx_EC_WFx] = kvm_handle_wfx,
179 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
180 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
181 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32,
182 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store,
183 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64,
184 [ESR_ELx_EC_HVC32] = handle_hvc,
185 [ESR_ELx_EC_SMC32] = handle_smc,
186 [ESR_ELx_EC_HVC64] = handle_hvc,
187 [ESR_ELx_EC_SMC64] = handle_smc,
188 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
189 [ESR_ELx_EC_SVE] = handle_sve,
190 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
191 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
192 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
193 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
194 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
195 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
196 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
197 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
198 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth,
199 };
200
kvm_get_exit_handler(struct kvm_vcpu * vcpu)201 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
202 {
203 u32 esr = kvm_vcpu_get_esr(vcpu);
204 u8 esr_ec = ESR_ELx_EC(esr);
205
206 return arm_exit_handlers[esr_ec];
207 }
208
209 /*
210 * We may be single-stepping an emulated instruction. If the emulation
211 * has been completed in the kernel, we can return to userspace with a
212 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
213 * emulation first.
214 */
handle_trap_exceptions(struct kvm_vcpu * vcpu)215 static int handle_trap_exceptions(struct kvm_vcpu *vcpu)
216 {
217 int handled;
218
219 /*
220 * See ARM ARM B1.14.1: "Hyp traps on instructions
221 * that fail their condition code check"
222 */
223 if (!kvm_condition_valid(vcpu)) {
224 kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
225 handled = 1;
226 } else {
227 exit_handle_fn exit_handler;
228
229 exit_handler = kvm_get_exit_handler(vcpu);
230 handled = exit_handler(vcpu);
231 }
232
233 return handled;
234 }
235
236 /*
237 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
238 * proper exit to userspace.
239 */
handle_exit(struct kvm_vcpu * vcpu,int exception_index)240 int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
241 {
242 struct kvm_run *run = vcpu->run;
243
244 if (ARM_SERROR_PENDING(exception_index)) {
245 u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
246
247 /*
248 * HVC/SMC already have an adjusted PC, which we need
249 * to correct in order to return to after having
250 * injected the SError.
251 */
252 if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64 ||
253 esr_ec == ESR_ELx_EC_SMC32 || esr_ec == ESR_ELx_EC_SMC64) {
254 u32 adj = kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
255 *vcpu_pc(vcpu) -= adj;
256 }
257
258 return 1;
259 }
260
261 exception_index = ARM_EXCEPTION_CODE(exception_index);
262
263 switch (exception_index) {
264 case ARM_EXCEPTION_IRQ:
265 return 1;
266 case ARM_EXCEPTION_EL1_SERROR:
267 return 1;
268 case ARM_EXCEPTION_TRAP:
269 return handle_trap_exceptions(vcpu);
270 case ARM_EXCEPTION_HYP_GONE:
271 /*
272 * EL2 has been reset to the hyp-stub. This happens when a guest
273 * is pre-empted by kvm_reboot()'s shutdown call.
274 */
275 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
276 return 0;
277 case ARM_EXCEPTION_IL:
278 /*
279 * We attempted an illegal exception return. Guest state must
280 * have been corrupted somehow. Give up.
281 */
282 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
283 return -EINVAL;
284 default:
285 kvm_pr_unimpl("Unsupported exception type: %d",
286 exception_index);
287 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
288 return 0;
289 }
290 }
291
292 /* For exit types that need handling before we can be preempted */
handle_exit_early(struct kvm_vcpu * vcpu,int exception_index)293 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index)
294 {
295 if (ARM_SERROR_PENDING(exception_index)) {
296 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) {
297 u64 disr = kvm_vcpu_get_disr(vcpu);
298
299 kvm_handle_guest_serror(vcpu, disr_to_esr(disr));
300 } else {
301 kvm_inject_vabt(vcpu);
302 }
303
304 return;
305 }
306
307 exception_index = ARM_EXCEPTION_CODE(exception_index);
308
309 if (exception_index == ARM_EXCEPTION_EL1_SERROR)
310 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu));
311 }
312