1 /* 2 * Copyright 2014 IBM Corp. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 */ 9 10 #include <linux/workqueue.h> 11 #include <linux/sched/signal.h> 12 #include <linux/sched/mm.h> 13 #include <linux/pid.h> 14 #include <linux/mm.h> 15 #include <linux/moduleparam.h> 16 17 #undef MODULE_PARAM_PREFIX 18 #define MODULE_PARAM_PREFIX "cxl" "." 19 #include <asm/current.h> 20 #include <asm/copro.h> 21 #include <asm/mmu.h> 22 23 #include "cxl.h" 24 #include "trace.h" 25 26 static bool sste_matches(struct cxl_sste *sste, struct copro_slb *slb) 27 { 28 return ((sste->vsid_data == cpu_to_be64(slb->vsid)) && 29 (sste->esid_data == cpu_to_be64(slb->esid))); 30 } 31 32 /* 33 * This finds a free SSTE for the given SLB, or returns NULL if it's already in 34 * the segment table. 35 */ 36 static struct cxl_sste *find_free_sste(struct cxl_context *ctx, 37 struct copro_slb *slb) 38 { 39 struct cxl_sste *primary, *sste, *ret = NULL; 40 unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */ 41 unsigned int entry; 42 unsigned int hash; 43 44 if (slb->vsid & SLB_VSID_B_1T) 45 hash = (slb->esid >> SID_SHIFT_1T) & mask; 46 else /* 256M */ 47 hash = (slb->esid >> SID_SHIFT) & mask; 48 49 primary = ctx->sstp + (hash << 3); 50 51 for (entry = 0, sste = primary; entry < 8; entry++, sste++) { 52 if (!ret && !(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) 53 ret = sste; 54 if (sste_matches(sste, slb)) 55 return NULL; 56 } 57 if (ret) 58 return ret; 59 60 /* Nothing free, select an entry to cast out */ 61 ret = primary + ctx->sst_lru; 62 ctx->sst_lru = (ctx->sst_lru + 1) & 0x7; 63 64 return ret; 65 } 66 67 static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) 68 { 69 /* mask is the group index, we search primary and secondary here. */ 70 struct cxl_sste *sste; 71 unsigned long flags; 72 73 spin_lock_irqsave(&ctx->sste_lock, flags); 74 sste = find_free_sste(ctx, slb); 75 if (!sste) 76 goto out_unlock; 77 78 pr_devel("CXL Populating SST[%li]: %#llx %#llx\n", 79 sste - ctx->sstp, slb->vsid, slb->esid); 80 trace_cxl_ste_write(ctx, sste - ctx->sstp, slb->esid, slb->vsid); 81 82 sste->vsid_data = cpu_to_be64(slb->vsid); 83 sste->esid_data = cpu_to_be64(slb->esid); 84 out_unlock: 85 spin_unlock_irqrestore(&ctx->sste_lock, flags); 86 } 87 88 static int cxl_fault_segment(struct cxl_context *ctx, struct mm_struct *mm, 89 u64 ea) 90 { 91 struct copro_slb slb = {0,0}; 92 int rc; 93 94 if (!(rc = copro_calculate_slb(mm, ea, &slb))) { 95 cxl_load_segment(ctx, &slb); 96 } 97 98 return rc; 99 } 100 101 static void cxl_ack_ae(struct cxl_context *ctx) 102 { 103 unsigned long flags; 104 105 cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_AE, 0); 106 107 spin_lock_irqsave(&ctx->lock, flags); 108 ctx->pending_fault = true; 109 ctx->fault_addr = ctx->dar; 110 ctx->fault_dsisr = ctx->dsisr; 111 spin_unlock_irqrestore(&ctx->lock, flags); 112 113 wake_up_all(&ctx->wq); 114 } 115 116 static int cxl_handle_segment_miss(struct cxl_context *ctx, 117 struct mm_struct *mm, u64 ea) 118 { 119 int rc; 120 121 pr_devel("CXL interrupt: Segment fault pe: %i ea: %#llx\n", ctx->pe, ea); 122 trace_cxl_ste_miss(ctx, ea); 123 124 if ((rc = cxl_fault_segment(ctx, mm, ea))) 125 cxl_ack_ae(ctx); 126 else { 127 128 mb(); /* Order seg table write to TFC MMIO write */ 129 cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0); 130 } 131 132 return IRQ_HANDLED; 133 } 134 135 int cxl_handle_mm_fault(struct mm_struct *mm, u64 dsisr, u64 dar) 136 { 137 vm_fault_t flt = 0; 138 int result; 139 unsigned long access, flags, inv_flags = 0; 140 141 /* 142 * Add the fault handling cpu to task mm cpumask so that we 143 * can do a safe lockless page table walk when inserting the 144 * hash page table entry. This function get called with a 145 * valid mm for user space addresses. Hence using the if (mm) 146 * check is sufficient here. 147 */ 148 if (mm && !cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm))) { 149 cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); 150 /* 151 * We need to make sure we walk the table only after 152 * we update the cpumask. The other side of the barrier 153 * is explained in serialize_against_pte_lookup() 154 */ 155 smp_mb(); 156 } 157 if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) { 158 pr_devel("copro_handle_mm_fault failed: %#x\n", result); 159 return result; 160 } 161 162 if (!radix_enabled()) { 163 /* 164 * update_mmu_cache() will not have loaded the hash since current->trap 165 * is not a 0x400 or 0x300, so just call hash_page_mm() here. 166 */ 167 access = _PAGE_PRESENT | _PAGE_READ; 168 if (dsisr & CXL_PSL_DSISR_An_S) 169 access |= _PAGE_WRITE; 170 171 if (!mm && (REGION_ID(dar) != USER_REGION_ID)) 172 access |= _PAGE_PRIVILEGED; 173 174 if (dsisr & DSISR_NOHPTE) 175 inv_flags |= HPTE_NOHPTE_UPDATE; 176 177 local_irq_save(flags); 178 hash_page_mm(mm, dar, access, 0x300, inv_flags); 179 local_irq_restore(flags); 180 } 181 return 0; 182 } 183 184 static void cxl_handle_page_fault(struct cxl_context *ctx, 185 struct mm_struct *mm, 186 u64 dsisr, u64 dar) 187 { 188 trace_cxl_pte_miss(ctx, dsisr, dar); 189 190 if (cxl_handle_mm_fault(mm, dsisr, dar)) { 191 cxl_ack_ae(ctx); 192 } else { 193 pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe); 194 cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0); 195 } 196 } 197 198 /* 199 * Returns the mm_struct corresponding to the context ctx. 200 * mm_users == 0, the context may be in the process of being closed. 201 */ 202 static struct mm_struct *get_mem_context(struct cxl_context *ctx) 203 { 204 if (ctx->mm == NULL) 205 return NULL; 206 207 if (!atomic_inc_not_zero(&ctx->mm->mm_users)) 208 return NULL; 209 210 return ctx->mm; 211 } 212 213 static bool cxl_is_segment_miss(struct cxl_context *ctx, u64 dsisr) 214 { 215 if ((cxl_is_power8() && (dsisr & CXL_PSL_DSISR_An_DS))) 216 return true; 217 218 return false; 219 } 220 221 static bool cxl_is_page_fault(struct cxl_context *ctx, u64 dsisr) 222 { 223 if ((cxl_is_power8()) && (dsisr & CXL_PSL_DSISR_An_DM)) 224 return true; 225 226 if (cxl_is_power9()) 227 return true; 228 229 return false; 230 } 231 232 void cxl_handle_fault(struct work_struct *fault_work) 233 { 234 struct cxl_context *ctx = 235 container_of(fault_work, struct cxl_context, fault_work); 236 u64 dsisr = ctx->dsisr; 237 u64 dar = ctx->dar; 238 struct mm_struct *mm = NULL; 239 240 if (cpu_has_feature(CPU_FTR_HVMODE)) { 241 if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr || 242 cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar || 243 cxl_p2n_read(ctx->afu, CXL_PSL_PEHandle_An) != ctx->pe) { 244 /* Most likely explanation is harmless - a dedicated 245 * process has detached and these were cleared by the 246 * PSL purge, but warn about it just in case 247 */ 248 dev_notice(&ctx->afu->dev, "cxl_handle_fault: Translation fault regs changed\n"); 249 return; 250 } 251 } 252 253 /* Early return if the context is being / has been detached */ 254 if (ctx->status == CLOSED) { 255 cxl_ack_ae(ctx); 256 return; 257 } 258 259 pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. " 260 "DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar); 261 262 if (!ctx->kernel) { 263 264 mm = get_mem_context(ctx); 265 if (mm == NULL) { 266 pr_devel("%s: unable to get mm for pe=%d pid=%i\n", 267 __func__, ctx->pe, pid_nr(ctx->pid)); 268 cxl_ack_ae(ctx); 269 return; 270 } else { 271 pr_devel("Handling page fault for pe=%d pid=%i\n", 272 ctx->pe, pid_nr(ctx->pid)); 273 } 274 } 275 276 if (cxl_is_segment_miss(ctx, dsisr)) 277 cxl_handle_segment_miss(ctx, mm, dar); 278 else if (cxl_is_page_fault(ctx, dsisr)) 279 cxl_handle_page_fault(ctx, mm, dsisr, dar); 280 else 281 WARN(1, "cxl_handle_fault has nothing to handle\n"); 282 283 if (mm) 284 mmput(mm); 285 } 286 287 static void cxl_prefault_one(struct cxl_context *ctx, u64 ea) 288 { 289 struct mm_struct *mm; 290 291 mm = get_mem_context(ctx); 292 if (mm == NULL) { 293 pr_devel("cxl_prefault_one unable to get mm %i\n", 294 pid_nr(ctx->pid)); 295 return; 296 } 297 298 cxl_fault_segment(ctx, mm, ea); 299 300 mmput(mm); 301 } 302 303 static u64 next_segment(u64 ea, u64 vsid) 304 { 305 if (vsid & SLB_VSID_B_1T) 306 ea |= (1ULL << 40) - 1; 307 else 308 ea |= (1ULL << 28) - 1; 309 310 return ea + 1; 311 } 312 313 static void cxl_prefault_vma(struct cxl_context *ctx) 314 { 315 u64 ea, last_esid = 0; 316 struct copro_slb slb; 317 struct vm_area_struct *vma; 318 int rc; 319 struct mm_struct *mm; 320 321 mm = get_mem_context(ctx); 322 if (mm == NULL) { 323 pr_devel("cxl_prefault_vm unable to get mm %i\n", 324 pid_nr(ctx->pid)); 325 return; 326 } 327 328 down_read(&mm->mmap_sem); 329 for (vma = mm->mmap; vma; vma = vma->vm_next) { 330 for (ea = vma->vm_start; ea < vma->vm_end; 331 ea = next_segment(ea, slb.vsid)) { 332 rc = copro_calculate_slb(mm, ea, &slb); 333 if (rc) 334 continue; 335 336 if (last_esid == slb.esid) 337 continue; 338 339 cxl_load_segment(ctx, &slb); 340 last_esid = slb.esid; 341 } 342 } 343 up_read(&mm->mmap_sem); 344 345 mmput(mm); 346 } 347 348 void cxl_prefault(struct cxl_context *ctx, u64 wed) 349 { 350 switch (ctx->afu->prefault_mode) { 351 case CXL_PREFAULT_WED: 352 cxl_prefault_one(ctx, wed); 353 break; 354 case CXL_PREFAULT_ALL: 355 cxl_prefault_vma(ctx); 356 break; 357 default: 358 break; 359 } 360 } 361