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/opal.h>
13 #include <asm/mce.h>
14 #include <asm/machdep.h>
15 #include <asm/cputhreads.h>
16 #include <asm/hmi.h>
17 #include <asm/kvm_ppc.h>
18
19 /* SRR1 bits for machine check on POWER7 */
20 #define SRR1_MC_LDSTERR (1ul << (63-42))
21 #define SRR1_MC_IFETCH_SH (63-45)
22 #define SRR1_MC_IFETCH_MASK 0x7
23 #define SRR1_MC_IFETCH_SLBPAR 2 /* SLB parity error */
24 #define SRR1_MC_IFETCH_SLBMULTI 3 /* SLB multi-hit */
25 #define SRR1_MC_IFETCH_SLBPARMULTI 4 /* SLB parity + multi-hit */
26 #define SRR1_MC_IFETCH_TLBMULTI 5 /* I-TLB multi-hit */
27
28 /* DSISR bits for machine check on POWER7 */
29 #define DSISR_MC_DERAT_MULTI 0x800 /* D-ERAT multi-hit */
30 #define DSISR_MC_TLB_MULTI 0x400 /* D-TLB multi-hit */
31 #define DSISR_MC_SLB_PARITY 0x100 /* SLB parity error */
32 #define DSISR_MC_SLB_MULTI 0x080 /* SLB multi-hit */
33 #define DSISR_MC_SLB_PARMULTI 0x040 /* SLB parity + multi-hit */
34
35 /* POWER7 SLB flush and reload */
36 static void reload_slb(struct kvm_vcpu *vcpu)
37 {
38 struct slb_shadow *slb;
39 unsigned long i, n;
40
41 /* First clear out SLB */
42 asm volatile("slbmte %0,%0; slbia" : : "r" (0));
43
44 /* Do they have an SLB shadow buffer registered? */
45 slb = vcpu->arch.slb_shadow.pinned_addr;
46 if (!slb)
47 return;
48
49 /* Sanity check */
50 n = min_t(u32, be32_to_cpu(slb->persistent), SLB_MIN_SIZE);
51 if ((void *) &slb->save_area[n] > vcpu->arch.slb_shadow.pinned_end)
52 return;
53
54 /* Load up the SLB from that */
55 for (i = 0; i < n; ++i) {
56 unsigned long rb = be64_to_cpu(slb->save_area[i].esid);
57 unsigned long rs = be64_to_cpu(slb->save_area[i].vsid);
58
59 rb = (rb & ~0xFFFul) | i; /* insert entry number */
60 asm volatile("slbmte %0,%1" : : "r" (rs), "r" (rb));
61 }
62 }
63
64 /*
65 * On POWER7, see if we can handle a machine check that occurred inside
66 * the guest in real mode, without switching to the host partition.
67 */
68 static void kvmppc_realmode_mc_power7(struct kvm_vcpu *vcpu)
69 {
70 unsigned long srr1 = vcpu->arch.shregs.msr;
71 struct machine_check_event mce_evt;
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 /*
110 * Now get the event and stash it in the vcpu struct so it can
111 * be handled by the primary thread in virtual mode. We can't
112 * call machine_check_queue_event() here if we are running on
113 * an offline secondary thread.
114 */
115 if (get_mce_event(&mce_evt, MCE_EVENT_RELEASE)) {
116 if (handled && mce_evt.version == MCE_V1)
117 mce_evt.disposition = MCE_DISPOSITION_RECOVERED;
118 } else {
119 memset(&mce_evt, 0, sizeof(mce_evt));
120 }
121
122 vcpu->arch.mce_evt = mce_evt;
123 }
124
125 void kvmppc_realmode_machine_check(struct kvm_vcpu *vcpu)
126 {
127 kvmppc_realmode_mc_power7(vcpu);
128 }
129
130 /* Check if dynamic split is in force and return subcore size accordingly. */
131 static inline int kvmppc_cur_subcore_size(void)
132 {
133 if (local_paca->kvm_hstate.kvm_split_mode)
134 return local_paca->kvm_hstate.kvm_split_mode->subcore_size;
135
136 return threads_per_subcore;
137 }
138
139 void kvmppc_subcore_enter_guest(void)
140 {
141 int thread_id, subcore_id;
142
143 thread_id = cpu_thread_in_core(local_paca->paca_index);
144 subcore_id = thread_id / kvmppc_cur_subcore_size();
145
146 local_paca->sibling_subcore_state->in_guest[subcore_id] = 1;
147 }
148 EXPORT_SYMBOL_GPL(kvmppc_subcore_enter_guest);
149
150 void kvmppc_subcore_exit_guest(void)
151 {
152 int thread_id, subcore_id;
153
154 thread_id = cpu_thread_in_core(local_paca->paca_index);
155 subcore_id = thread_id / kvmppc_cur_subcore_size();
156
157 local_paca->sibling_subcore_state->in_guest[subcore_id] = 0;
158 }
159 EXPORT_SYMBOL_GPL(kvmppc_subcore_exit_guest);
160
161 static bool kvmppc_tb_resync_required(void)
162 {
163 if (test_and_set_bit(CORE_TB_RESYNC_REQ_BIT,
164 &local_paca->sibling_subcore_state->flags))
165 return false;
166
167 return true;
168 }
169
170 static void kvmppc_tb_resync_done(void)
171 {
172 clear_bit(CORE_TB_RESYNC_REQ_BIT,
173 &local_paca->sibling_subcore_state->flags);
174 }
175
176 /*
177 * kvmppc_realmode_hmi_handler() is called only by primary thread during
178 * guest exit path.
179 *
180 * There are multiple reasons why HMI could occur, one of them is
181 * Timebase (TB) error. If this HMI is due to TB error, then TB would
182 * have been in stopped state. The opal hmi handler Will fix it and
183 * restore the TB value with host timebase value. For HMI caused due
184 * to non-TB errors, opal hmi handler will not touch/restore TB register
185 * and hence there won't be any change in TB value.
186 *
187 * Since we are not sure about the cause of this HMI, we can't be sure
188 * about the content of TB register whether it holds guest or host timebase
189 * value. Hence the idea is to resync the TB on every HMI, so that we
190 * know about the exact state of the TB value. Resync TB call will
191 * restore TB to host timebase.
192 *
193 * Things to consider:
194 * - On TB error, HMI interrupt is reported on all the threads of the core
195 * that has encountered TB error irrespective of split-core mode.
196 * - The very first thread on the core that get chance to fix TB error
197 * would rsync the TB with local chipTOD value.
198 * - The resync TB is a core level action i.e. it will sync all the TBs
199 * in that core independent of split-core mode. This means if we trigger
200 * TB sync from a thread from one subcore, it would affect TB values of
201 * sibling subcores of the same core.
202 *
203 * All threads need to co-ordinate before making opal hmi handler.
204 * All threads will use sibling_subcore_state->in_guest[] (shared by all
205 * threads in the core) in paca which holds information about whether
206 * sibling subcores are in Guest mode or host mode. The in_guest[] array
207 * is of size MAX_SUBCORE_PER_CORE=4, indexed using subcore id to set/unset
208 * subcore status. Only primary threads from each subcore is responsible
209 * to set/unset its designated array element while entering/exiting the
210 * guset.
211 *
212 * After invoking opal hmi handler call, one of the thread (of entire core)
213 * will need to resync the TB. Bit 63 from subcore state bitmap flags
214 * (sibling_subcore_state->flags) will be used to co-ordinate between
215 * primary threads to decide who takes up the responsibility.
216 *
217 * This is what we do:
218 * - Primary thread from each subcore tries to set resync required bit[63]
219 * of paca->sibling_subcore_state->flags.
220 * - The first primary thread that is able to set the flag takes the
221 * responsibility of TB resync. (Let us call it as thread leader)
222 * - All other threads which are in host will call
223 * wait_for_subcore_guest_exit() and wait for in_guest[0-3] from
224 * paca->sibling_subcore_state to get cleared.
225 * - All the primary thread will clear its subcore status from subcore
226 * state in_guest[] array respectively.
227 * - Once all primary threads clear in_guest[0-3], all of them will invoke
228 * opal hmi handler.
229 * - Now all threads will wait for TB resync to complete by invoking
230 * wait_for_tb_resync() except the thread leader.
231 * - Thread leader will do a TB resync by invoking opal_resync_timebase()
232 * call and the it will clear the resync required bit.
233 * - All other threads will now come out of resync wait loop and proceed
234 * with individual execution.
235 * - On return of this function, primary thread will signal all
236 * secondary threads to proceed.
237 * - All secondary threads will eventually call opal hmi handler on
238 * their exit path.
239 *
240 * Returns 1 if the timebase offset should be applied, 0 if not.
241 */
242
243 long kvmppc_realmode_hmi_handler(void)
244 {
245 bool resync_req;
246
247 __this_cpu_inc(irq_stat.hmi_exceptions);
248
249 if (hmi_handle_debugtrig(NULL) >= 0)
250 return 1;
251
252 /*
253 * By now primary thread has already completed guest->host
254 * partition switch but haven't signaled secondaries yet.
255 * All the secondary threads on this subcore is waiting
256 * for primary thread to signal them to go ahead.
257 *
258 * For threads from subcore which isn't in guest, they all will
259 * wait until all other subcores on this core exit the guest.
260 *
261 * Now set the resync required bit. If you are the first to
262 * set this bit then kvmppc_tb_resync_required() function will
263 * return true. For rest all other subcores
264 * kvmppc_tb_resync_required() will return false.
265 *
266 * If resync_req == true, then this thread is responsible to
267 * initiate TB resync after hmi handler has completed.
268 * All other threads on this core will wait until this thread
269 * clears the resync required bit flag.
270 */
271 resync_req = kvmppc_tb_resync_required();
272
273 /* Reset the subcore status to indicate it has exited guest */
274 kvmppc_subcore_exit_guest();
275
276 /*
277 * Wait for other subcores on this core to exit the guest.
278 * All the primary threads and threads from subcore that are
279 * not in guest will wait here until all subcores are out
280 * of guest context.
281 */
282 wait_for_subcore_guest_exit();
283
284 /*
285 * At this point we are sure that primary threads from each
286 * subcore on this core have completed guest->host partition
287 * switch. Now it is safe to call HMI handler.
288 */
289 if (ppc_md.hmi_exception_early)
290 ppc_md.hmi_exception_early(NULL);
291
292 /*
293 * Check if this thread is responsible to resync TB.
294 * All other threads will wait until this thread completes the
295 * TB resync.
296 */
297 if (resync_req) {
298 opal_resync_timebase();
299 /* Reset TB resync req bit */
300 kvmppc_tb_resync_done();
301 } else {
302 wait_for_tb_resync();
303 }
304
305 /*
306 * Reset tb_offset_applied so the guest exit code won't try
307 * to subtract the previous timebase offset from the timebase.
308 */
309 if (local_paca->kvm_hstate.kvm_vcore)
310 local_paca->kvm_hstate.kvm_vcore->tb_offset_applied = 0;
311
312 return 0;
313 }