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 local_paca->hmi_irqs++; 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 } 314