1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 *
4 * Copyright 2012 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
5 */
6
7 #include <linux/types.h>
8 #include <linux/string.h>
9 #include <linux/kvm.h>
10 #include <linux/kvm_host.h>
11 #include <linux/kernel.h>
12 #include <asm/lppaca.h>
13 #include <asm/opal.h>
14 #include <asm/mce.h>
15 #include <asm/machdep.h>
16 #include <asm/cputhreads.h>
17 #include <asm/hmi.h>
18 #include <asm/kvm_ppc.h>
19
20 /* SRR1 bits for machine check on POWER7 */
21 #define SRR1_MC_LDSTERR (1ul << (63-42))
22 #define SRR1_MC_IFETCH_SH (63-45)
23 #define SRR1_MC_IFETCH_MASK 0x7
24 #define SRR1_MC_IFETCH_SLBPAR 2 /* SLB parity error */
25 #define SRR1_MC_IFETCH_SLBMULTI 3 /* SLB multi-hit */
26 #define SRR1_MC_IFETCH_SLBPARMULTI 4 /* SLB parity + multi-hit */
27 #define SRR1_MC_IFETCH_TLBMULTI 5 /* I-TLB multi-hit */
28
29 /* DSISR bits for machine check on POWER7 */
30 #define DSISR_MC_DERAT_MULTI 0x800 /* D-ERAT multi-hit */
31 #define DSISR_MC_TLB_MULTI 0x400 /* D-TLB multi-hit */
32 #define DSISR_MC_SLB_PARITY 0x100 /* SLB parity error */
33 #define DSISR_MC_SLB_MULTI 0x080 /* SLB multi-hit */
34 #define DSISR_MC_SLB_PARMULTI 0x040 /* SLB parity + multi-hit */
35
36 /* POWER7 SLB flush and reload */
reload_slb(struct kvm_vcpu * vcpu)37 static void reload_slb(struct kvm_vcpu *vcpu)
38 {
39 struct slb_shadow *slb;
40 unsigned long i, n;
41
42 /* First clear out SLB */
43 asm volatile("slbmte %0,%0; slbia" : : "r" (0));
44
45 /* Do they have an SLB shadow buffer registered? */
46 slb = vcpu->arch.slb_shadow.pinned_addr;
47 if (!slb)
48 return;
49
50 /* Sanity check */
51 n = min_t(u32, be32_to_cpu(slb->persistent), SLB_MIN_SIZE);
52 if ((void *) &slb->save_area[n] > vcpu->arch.slb_shadow.pinned_end)
53 return;
54
55 /* Load up the SLB from that */
56 for (i = 0; i < n; ++i) {
57 unsigned long rb = be64_to_cpu(slb->save_area[i].esid);
58 unsigned long rs = be64_to_cpu(slb->save_area[i].vsid);
59
60 rb = (rb & ~0xFFFul) | i; /* insert entry number */
61 asm volatile("slbmte %0,%1" : : "r" (rs), "r" (rb));
62 }
63 }
64
65 /*
66 * On POWER7, see if we can handle a machine check that occurred inside
67 * the guest in real mode, without switching to the host partition.
68 */
kvmppc_realmode_mc_power7(struct kvm_vcpu * vcpu)69 static long kvmppc_realmode_mc_power7(struct kvm_vcpu *vcpu)
70 {
71 unsigned long srr1 = vcpu->arch.shregs.msr;
72 long handled = 1;
73
74 if (srr1 & SRR1_MC_LDSTERR) {
75 /* error on load/store */
76 unsigned long dsisr = vcpu->arch.shregs.dsisr;
77
78 if (dsisr & (DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
79 DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI)) {
80 /* flush and reload SLB; flushes D-ERAT too */
81 reload_slb(vcpu);
82 dsisr &= ~(DSISR_MC_SLB_PARMULTI | DSISR_MC_SLB_MULTI |
83 DSISR_MC_SLB_PARITY | DSISR_MC_DERAT_MULTI);
84 }
85 if (dsisr & DSISR_MC_TLB_MULTI) {
86 tlbiel_all_lpid(vcpu->kvm->arch.radix);
87 dsisr &= ~DSISR_MC_TLB_MULTI;
88 }
89 /* Any other errors we don't understand? */
90 if (dsisr & 0xffffffffUL)
91 handled = 0;
92 }
93
94 switch ((srr1 >> SRR1_MC_IFETCH_SH) & SRR1_MC_IFETCH_MASK) {
95 case 0:
96 break;
97 case SRR1_MC_IFETCH_SLBPAR:
98 case SRR1_MC_IFETCH_SLBMULTI:
99 case SRR1_MC_IFETCH_SLBPARMULTI:
100 reload_slb(vcpu);
101 break;
102 case SRR1_MC_IFETCH_TLBMULTI:
103 tlbiel_all_lpid(vcpu->kvm->arch.radix);
104 break;
105 default:
106 handled = 0;
107 }
108
109 return handled;
110 }
111
kvmppc_realmode_machine_check(struct kvm_vcpu * vcpu)112 void kvmppc_realmode_machine_check(struct kvm_vcpu *vcpu)
113 {
114 struct machine_check_event mce_evt;
115 long handled;
116
117 if (vcpu->kvm->arch.fwnmi_enabled) {
118 /* FWNMI guests handle their own recovery */
119 handled = 0;
120 } else {
121 handled = kvmppc_realmode_mc_power7(vcpu);
122 }
123
124 /*
125 * Now get the event and stash it in the vcpu struct so it can
126 * be handled by the primary thread in virtual mode. We can't
127 * call machine_check_queue_event() here if we are running on
128 * an offline secondary thread.
129 */
130 if (get_mce_event(&mce_evt, MCE_EVENT_RELEASE)) {
131 if (handled && mce_evt.version == MCE_V1)
132 mce_evt.disposition = MCE_DISPOSITION_RECOVERED;
133 } else {
134 memset(&mce_evt, 0, sizeof(mce_evt));
135 }
136
137 vcpu->arch.mce_evt = mce_evt;
138 }
139
140
kvmppc_p9_realmode_hmi_handler(struct kvm_vcpu * vcpu)141 long kvmppc_p9_realmode_hmi_handler(struct kvm_vcpu *vcpu)
142 {
143 struct kvmppc_vcore *vc = vcpu->arch.vcore;
144 long ret = 0;
145
146 /*
147 * Unapply and clear the offset first. That way, if the TB was not
148 * resynced then it will remain in host-offset, and if it was resynced
149 * then it is brought into host-offset. Then the tb offset is
150 * re-applied before continuing with the KVM exit.
151 *
152 * This way, we don't need to actually know whether not OPAL resynced
153 * the timebase or do any of the complicated dance that the P7/8
154 * path requires.
155 */
156 if (vc->tb_offset_applied) {
157 u64 new_tb = mftb() - vc->tb_offset_applied;
158 mtspr(SPRN_TBU40, new_tb);
159 if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
160 new_tb += 0x1000000;
161 mtspr(SPRN_TBU40, new_tb);
162 }
163 vc->tb_offset_applied = 0;
164 }
165
166 local_paca->hmi_irqs++;
167
168 if (hmi_handle_debugtrig(NULL) >= 0) {
169 ret = 1;
170 goto out;
171 }
172
173 if (ppc_md.hmi_exception_early)
174 ppc_md.hmi_exception_early(NULL);
175
176 out:
177 if (vc->tb_offset) {
178 u64 new_tb = mftb() + vc->tb_offset;
179 mtspr(SPRN_TBU40, new_tb);
180 if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) {
181 new_tb += 0x1000000;
182 mtspr(SPRN_TBU40, new_tb);
183 }
184 vc->tb_offset_applied = vc->tb_offset;
185 }
186
187 return ret;
188 }
189
190 /*
191 * The following subcore HMI handling is all only for pre-POWER9 CPUs.
192 */
193
194 /* Check if dynamic split is in force and return subcore size accordingly. */
kvmppc_cur_subcore_size(void)195 static inline int kvmppc_cur_subcore_size(void)
196 {
197 if (local_paca->kvm_hstate.kvm_split_mode)
198 return local_paca->kvm_hstate.kvm_split_mode->subcore_size;
199
200 return threads_per_subcore;
201 }
202
kvmppc_subcore_enter_guest(void)203 void kvmppc_subcore_enter_guest(void)
204 {
205 int thread_id, subcore_id;
206
207 thread_id = cpu_thread_in_core(local_paca->paca_index);
208 subcore_id = thread_id / kvmppc_cur_subcore_size();
209
210 local_paca->sibling_subcore_state->in_guest[subcore_id] = 1;
211 }
212 EXPORT_SYMBOL_GPL(kvmppc_subcore_enter_guest);
213
kvmppc_subcore_exit_guest(void)214 void kvmppc_subcore_exit_guest(void)
215 {
216 int thread_id, subcore_id;
217
218 thread_id = cpu_thread_in_core(local_paca->paca_index);
219 subcore_id = thread_id / kvmppc_cur_subcore_size();
220
221 local_paca->sibling_subcore_state->in_guest[subcore_id] = 0;
222 }
223 EXPORT_SYMBOL_GPL(kvmppc_subcore_exit_guest);
224
kvmppc_tb_resync_required(void)225 static bool kvmppc_tb_resync_required(void)
226 {
227 if (test_and_set_bit(CORE_TB_RESYNC_REQ_BIT,
228 &local_paca->sibling_subcore_state->flags))
229 return false;
230
231 return true;
232 }
233
kvmppc_tb_resync_done(void)234 static void kvmppc_tb_resync_done(void)
235 {
236 clear_bit(CORE_TB_RESYNC_REQ_BIT,
237 &local_paca->sibling_subcore_state->flags);
238 }
239
240 /*
241 * kvmppc_realmode_hmi_handler() is called only by primary thread during
242 * guest exit path.
243 *
244 * There are multiple reasons why HMI could occur, one of them is
245 * Timebase (TB) error. If this HMI is due to TB error, then TB would
246 * have been in stopped state. The opal hmi handler Will fix it and
247 * restore the TB value with host timebase value. For HMI caused due
248 * to non-TB errors, opal hmi handler will not touch/restore TB register
249 * and hence there won't be any change in TB value.
250 *
251 * Since we are not sure about the cause of this HMI, we can't be sure
252 * about the content of TB register whether it holds guest or host timebase
253 * value. Hence the idea is to resync the TB on every HMI, so that we
254 * know about the exact state of the TB value. Resync TB call will
255 * restore TB to host timebase.
256 *
257 * Things to consider:
258 * - On TB error, HMI interrupt is reported on all the threads of the core
259 * that has encountered TB error irrespective of split-core mode.
260 * - The very first thread on the core that get chance to fix TB error
261 * would rsync the TB with local chipTOD value.
262 * - The resync TB is a core level action i.e. it will sync all the TBs
263 * in that core independent of split-core mode. This means if we trigger
264 * TB sync from a thread from one subcore, it would affect TB values of
265 * sibling subcores of the same core.
266 *
267 * All threads need to co-ordinate before making opal hmi handler.
268 * All threads will use sibling_subcore_state->in_guest[] (shared by all
269 * threads in the core) in paca which holds information about whether
270 * sibling subcores are in Guest mode or host mode. The in_guest[] array
271 * is of size MAX_SUBCORE_PER_CORE=4, indexed using subcore id to set/unset
272 * subcore status. Only primary threads from each subcore is responsible
273 * to set/unset its designated array element while entering/exiting the
274 * guset.
275 *
276 * After invoking opal hmi handler call, one of the thread (of entire core)
277 * will need to resync the TB. Bit 63 from subcore state bitmap flags
278 * (sibling_subcore_state->flags) will be used to co-ordinate between
279 * primary threads to decide who takes up the responsibility.
280 *
281 * This is what we do:
282 * - Primary thread from each subcore tries to set resync required bit[63]
283 * of paca->sibling_subcore_state->flags.
284 * - The first primary thread that is able to set the flag takes the
285 * responsibility of TB resync. (Let us call it as thread leader)
286 * - All other threads which are in host will call
287 * wait_for_subcore_guest_exit() and wait for in_guest[0-3] from
288 * paca->sibling_subcore_state to get cleared.
289 * - All the primary thread will clear its subcore status from subcore
290 * state in_guest[] array respectively.
291 * - Once all primary threads clear in_guest[0-3], all of them will invoke
292 * opal hmi handler.
293 * - Now all threads will wait for TB resync to complete by invoking
294 * wait_for_tb_resync() except the thread leader.
295 * - Thread leader will do a TB resync by invoking opal_resync_timebase()
296 * call and the it will clear the resync required bit.
297 * - All other threads will now come out of resync wait loop and proceed
298 * with individual execution.
299 * - On return of this function, primary thread will signal all
300 * secondary threads to proceed.
301 * - All secondary threads will eventually call opal hmi handler on
302 * their exit path.
303 *
304 * Returns 1 if the timebase offset should be applied, 0 if not.
305 */
306
kvmppc_realmode_hmi_handler(void)307 long kvmppc_realmode_hmi_handler(void)
308 {
309 bool resync_req;
310
311 local_paca->hmi_irqs++;
312
313 if (hmi_handle_debugtrig(NULL) >= 0)
314 return 1;
315
316 /*
317 * By now primary thread has already completed guest->host
318 * partition switch but haven't signaled secondaries yet.
319 * All the secondary threads on this subcore is waiting
320 * for primary thread to signal them to go ahead.
321 *
322 * For threads from subcore which isn't in guest, they all will
323 * wait until all other subcores on this core exit the guest.
324 *
325 * Now set the resync required bit. If you are the first to
326 * set this bit then kvmppc_tb_resync_required() function will
327 * return true. For rest all other subcores
328 * kvmppc_tb_resync_required() will return false.
329 *
330 * If resync_req == true, then this thread is responsible to
331 * initiate TB resync after hmi handler has completed.
332 * All other threads on this core will wait until this thread
333 * clears the resync required bit flag.
334 */
335 resync_req = kvmppc_tb_resync_required();
336
337 /* Reset the subcore status to indicate it has exited guest */
338 kvmppc_subcore_exit_guest();
339
340 /*
341 * Wait for other subcores on this core to exit the guest.
342 * All the primary threads and threads from subcore that are
343 * not in guest will wait here until all subcores are out
344 * of guest context.
345 */
346 wait_for_subcore_guest_exit();
347
348 /*
349 * At this point we are sure that primary threads from each
350 * subcore on this core have completed guest->host partition
351 * switch. Now it is safe to call HMI handler.
352 */
353 if (ppc_md.hmi_exception_early)
354 ppc_md.hmi_exception_early(NULL);
355
356 /*
357 * Check if this thread is responsible to resync TB.
358 * All other threads will wait until this thread completes the
359 * TB resync.
360 */
361 if (resync_req) {
362 opal_resync_timebase();
363 /* Reset TB resync req bit */
364 kvmppc_tb_resync_done();
365 } else {
366 wait_for_tb_resync();
367 }
368
369 /*
370 * Reset tb_offset_applied so the guest exit code won't try
371 * to subtract the previous timebase offset from the timebase.
372 */
373 if (local_paca->kvm_hstate.kvm_vcore)
374 local_paca->kvm_hstate.kvm_vcore->tb_offset_applied = 0;
375
376 return 0;
377 }
378
