1 // SPDX-License-Identifier: GPL-2.0-only 1
2 /*
3 * Debug and Guest Debug support
4 *
5 * Copyright (C) 2015 - Linaro Ltd
6 * Author: Alex Bennée <alex.bennee@linaro.or
7 */
8
9 #include <linux/kvm_host.h>
10 #include <linux/hw_breakpoint.h>
11
12 #include <asm/debug-monitors.h>
13 #include <asm/kvm_asm.h>
14 #include <asm/kvm_arm.h>
15 #include <asm/kvm_emulate.h>
16
17 #include "trace.h"
18
19 /* These are the bits of MDSCR_EL1 we may mani
20 #define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS
21 DBG_MDSCR_KDE
22 DBG_MDSCR_MDE)
23
24 static DEFINE_PER_CPU(u64, mdcr_el2);
25
26 /*
27 * save/restore_guest_debug_regs
28 *
29 * For some debug operations we need to tweak
30 * a result we need to save the state of those
31 * make those modifications.
32 *
33 * Guest access to MDSCR_EL1 is trapped by the
34 * after we have restored the preserved value
35 *
36 * When single-step is enabled by userspace, w
37 * guest entry. Preserve PSTATE.SS so we can r
38 * for the vcpu after the single-step is disab
39 */
40 static void save_guest_debug_regs(struct kvm_v
41 {
42 u64 val = vcpu_read_sys_reg(vcpu, MDSC
43
44 vcpu->arch.guest_debug_preserved.mdscr
45
46 trace_kvm_arm_set_dreg32("Saved MDSCR_
47 vcpu->arch.gue
48
49 vcpu->arch.guest_debug_preserved.pstat
50 (*vcpu
51 }
52
53 static void restore_guest_debug_regs(struct kv
54 {
55 u64 val = vcpu->arch.guest_debug_prese
56
57 vcpu_write_sys_reg(vcpu, val, MDSCR_EL
58
59 trace_kvm_arm_set_dreg32("Restored MDS
60 vcpu_read_sys_
61
62 if (vcpu->arch.guest_debug_preserved.p
63 *vcpu_cpsr(vcpu) |= DBG_SPSR_S
64 else
65 *vcpu_cpsr(vcpu) &= ~DBG_SPSR_
66 }
67
68 /**
69 * kvm_arm_init_debug - grab what we need for
70 *
71 * Currently the sole task of this function is
72 * value of mdcr_el2 so we can preserve MDCR_E
73 * presumably been set-up by some knowledgeabl
74 *
75 * It is called once per-cpu during CPU hyp in
76 */
77
78 void kvm_arm_init_debug(void)
79 {
80 __this_cpu_write(mdcr_el2, kvm_call_hy
81 }
82
83 /**
84 * kvm_arm_setup_mdcr_el2 - configure vcpu mdc
85 *
86 * @vcpu: the vcpu pointer
87 *
88 * This ensures we will trap access to:
89 * - Performance monitors (MDCR_EL2_TPM/MDCR_
90 * - Debug ROM Address (MDCR_EL2_TDRA)
91 * - OS related registers (MDCR_EL2_TDOSA)
92 * - Statistical profiler (MDCR_EL2_TPMS/MDCR
93 * - Self-hosted Trace Filter controls (MDCR_
94 * - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL
95 */
96 static void kvm_arm_setup_mdcr_el2(struct kvm_
97 {
98 /*
99 * This also clears MDCR_EL2_E2PB_MASK
100 * to disable guest access to the prof
101 */
102 vcpu->arch.mdcr_el2 = __this_cpu_read(
103 vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
104 MDCR_EL2_TPMS
105 MDCR_EL2_TTRF
106 MDCR_EL2_TPMCR
107 MDCR_EL2_TDRA
108 MDCR_EL2_TDOSA
109
110 /* Is the VM being debugged by userspa
111 if (vcpu->guest_debug)
112 /* Route all software debug ex
113 vcpu->arch.mdcr_el2 |= MDCR_EL
114
115 /*
116 * Trap debug register access when one
117 * - Userspace is using the hardware
118 * (KVM_GUESTDBG_USE_HW is set).
119 * - The guest is not using debug (DE
120 * - The guest has enabled the OS Loc
121 */
122 if ((vcpu->guest_debug & KVM_GUESTDBG_
123 !vcpu_get_flag(vcpu, DEBUG_DIRTY)
124 kvm_vcpu_os_lock_enabled(vcpu))
125 vcpu->arch.mdcr_el2 |= MDCR_EL
126
127 trace_kvm_arm_set_dreg32("MDCR_EL2", v
128 }
129
130 /**
131 * kvm_arm_vcpu_init_debug - setup vcpu debug
132 *
133 * @vcpu: the vcpu pointer
134 *
135 * Set vcpu initial mdcr_el2 value.
136 */
137 void kvm_arm_vcpu_init_debug(struct kvm_vcpu *
138 {
139 preempt_disable();
140 kvm_arm_setup_mdcr_el2(vcpu);
141 preempt_enable();
142 }
143
144 /**
145 * kvm_arm_reset_debug_ptr - reset the debug p
146 * @vcpu: the vcpu pointer
147 */
148
149 void kvm_arm_reset_debug_ptr(struct kvm_vcpu *
150 {
151 vcpu->arch.debug_ptr = &vcpu->arch.vcp
152 }
153
154 /**
155 * kvm_arm_setup_debug - set up debug related
156 *
157 * @vcpu: the vcpu pointer
158 *
159 * This is called before each entry into the h
160 * debug related registers.
161 *
162 * Additionally, KVM only traps guest accesses
163 * the guest is not actively using them (see t
164 * flag on vcpu->arch.iflags). Since the gues
165 * with the hardware state when debugging the
166 * trapping is enabled whenever we are debuggi
167 * debug registers.
168 */
169
170 void kvm_arm_setup_debug(struct kvm_vcpu *vcpu
171 {
172 unsigned long mdscr, orig_mdcr_el2 = v
173
174 trace_kvm_arm_setup_debug(vcpu, vcpu->
175
176 kvm_arm_setup_mdcr_el2(vcpu);
177
178 /* Check if we need to use the debug r
179 if (vcpu->guest_debug || kvm_vcpu_os_l
180 /* Save guest debug state */
181 save_guest_debug_regs(vcpu);
182
183 /*
184 * Single Step (ARM ARM D2.12.
185 * machine)
186 *
187 * If we are doing Single Step
188 * the guest's MDSCR_EL1.SS an
189 * step has occurred the hyper
190 * debug exception and we retu
191 *
192 * If the guest attempts to si
193 * we would have to deal with
194 * while in the guest kernel.
195 * hard to unwind we suppress
196 * do so by masking MDSCR_EL.S
197 *
198 * This confuses guest debugge
199 * single-step behind the scen
200 * returns to normal once the
201 * debugging the system.
202 */
203 if (vcpu->guest_debug & KVM_GU
204 /*
205 * If the software ste
206 * was Active-pending,
207 * that the state is m
208 * single-step until t
209 * exception is taken)
210 */
211 if (!vcpu_get_flag(vcp
212 *vcpu_cpsr(vcp
213 else
214 *vcpu_cpsr(vcp
215
216 mdscr = vcpu_read_sys_
217 mdscr |= DBG_MDSCR_SS;
218 vcpu_write_sys_reg(vcp
219 } else {
220 mdscr = vcpu_read_sys_
221 mdscr &= ~DBG_MDSCR_SS
222 vcpu_write_sys_reg(vcp
223 }
224
225 trace_kvm_arm_set_dreg32("SPSR
226
227 /*
228 * HW Breakpoints and watchpoi
229 *
230 * We simply switch the debug_
231 * external_debug_state which
232 * debug ioctl. The existing D
233 * the registers are updated o
234 */
235 if (vcpu->guest_debug & KVM_GU
236 /* Enable breakpoints/
237 mdscr = vcpu_read_sys_
238 mdscr |= DBG_MDSCR_MDE
239 vcpu_write_sys_reg(vcp
240
241 vcpu->arch.debug_ptr =
242 vcpu_set_flag(vcpu, DE
243
244 trace_kvm_arm_set_regs
245
246
247
248 trace_kvm_arm_set_regs
249
250
251
252 /*
253 * The OS Lock blocks debug ex
254 * enabled. If the guest has e
255 * effects to the guest. Emula
256 * MDSCR_EL1.MDE. In so doing,
257 * exceptions are unaffected b
258 * Lock.
259 */
260 } else if (kvm_vcpu_os_lock_en
261 mdscr = vcpu_read_sys_
262 mdscr &= ~DBG_MDSCR_MD
263 vcpu_write_sys_reg(vcp
264 }
265 }
266
267 BUG_ON(!vcpu->guest_debug &&
268 vcpu->arch.debug_ptr != &vcpu-
269
270 /* If KDE or MDE are set, perform a fu
271 if (vcpu_read_sys_reg(vcpu, MDSCR_EL1)
272 vcpu_set_flag(vcpu, DEBUG_DIRT
273
274 /* Write mdcr_el2 changes since vcpu_l
275 if (has_vhe() && orig_mdcr_el2 != vcpu
276 write_sysreg(vcpu->arch.mdcr_e
277
278 trace_kvm_arm_set_dreg32("MDSCR_EL1",
279 }
280
281 void kvm_arm_clear_debug(struct kvm_vcpu *vcpu
282 {
283 trace_kvm_arm_clear_debug(vcpu->guest_
284
285 /*
286 * Restore the guest's debug registers
287 */
288 if (vcpu->guest_debug || kvm_vcpu_os_l
289 if (vcpu->guest_debug & KVM_GU
290 if (!(*vcpu_cpsr(vcpu)
291 /*
292 * Mark the vc
293 * until Softw
294 */
295 vcpu_set_flag(
296 }
297
298 restore_guest_debug_regs(vcpu)
299
300 /*
301 * If we were using HW debug w
302 * debug_ptr to the guest debu
303 */
304 if (vcpu->guest_debug & KVM_GU
305 kvm_arm_reset_debug_pt
306
307 trace_kvm_arm_set_regs
308
309
310
311 trace_kvm_arm_set_regs
312
313
314 }
315 }
316 }
317
318 void kvm_arch_vcpu_load_debug_state_flags(stru
319 {
320 u64 dfr0;
321
322 /* For VHE, there is nothing to do */
323 if (has_vhe())
324 return;
325
326 dfr0 = read_sysreg(id_aa64dfr0_el1);
327 /*
328 * If SPE is present on this CPU and i
329 * we may need to check if the host st
330 */
331 if (cpuid_feature_extract_unsigned_fie
332 !(read_sysreg_s(SYS_PMBIDR_EL1) &
333 vcpu_set_flag(vcpu, DEBUG_STAT
334
335 /* Check if we have TRBE implemented a
336 if (cpuid_feature_extract_unsigned_fie
337 !(read_sysreg_s(SYS_TRBIDR_EL1) &
338 vcpu_set_flag(vcpu, DEBUG_STAT
339 }
340
341 void kvm_arch_vcpu_put_debug_state_flags(struc
342 {
343 vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE
344 vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE
345 }
346
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