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
28typedef int (*exit_handle_fn)(struct kvm_vcpu *);
29
30static 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
36static 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
53static 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 */
72static 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 */
90static 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 */
119static 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
147static 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
158static 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 */
170static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
171{
172	kvm_inject_undefined(vcpu);
173	return 1;
174}
175
176static 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
201static 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 */
215static 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 */
240int 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 */
293void 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