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.h> 12 #include <linux/pid.h> 13 #include <linux/mm.h> 14 #include <linux/moduleparam.h> 15 16 #undef MODULE_PARAM_PREFIX 17 #define MODULE_PARAM_PREFIX "cxl" "." 18 #include <asm/current.h> 19 #include <asm/copro.h> 20 #include <asm/mmu.h> 21 22 #include "cxl.h" 23 #include "trace.h" 24 25 static bool sste_matches(struct cxl_sste *sste, struct copro_slb *slb) 26 { 27 return ((sste->vsid_data == cpu_to_be64(slb->vsid)) && 28 (sste->esid_data == cpu_to_be64(slb->esid))); 29 } 30 31 /* 32 * This finds a free SSTE for the given SLB, or returns NULL if it's already in 33 * the segment table. 34 */ 35 static struct cxl_sste* find_free_sste(struct cxl_context *ctx, 36 struct copro_slb *slb) 37 { 38 struct cxl_sste *primary, *sste, *ret = NULL; 39 unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */ 40 unsigned int entry; 41 unsigned int hash; 42 43 if (slb->vsid & SLB_VSID_B_1T) 44 hash = (slb->esid >> SID_SHIFT_1T) & mask; 45 else /* 256M */ 46 hash = (slb->esid >> SID_SHIFT) & mask; 47 48 primary = ctx->sstp + (hash << 3); 49 50 for (entry = 0, sste = primary; entry < 8; entry++, sste++) { 51 if (!ret && !(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) 52 ret = sste; 53 if (sste_matches(sste, slb)) 54 return NULL; 55 } 56 if (ret) 57 return ret; 58 59 /* Nothing free, select an entry to cast out */ 60 ret = primary + ctx->sst_lru; 61 ctx->sst_lru = (ctx->sst_lru + 1) & 0x7; 62 63 return ret; 64 } 65 66 static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) 67 { 68 /* mask is the group index, we search primary and secondary here. */ 69 struct cxl_sste *sste; 70 unsigned long flags; 71 72 spin_lock_irqsave(&ctx->sste_lock, flags); 73 sste = find_free_sste(ctx, slb); 74 if (!sste) 75 goto out_unlock; 76 77 pr_devel("CXL Populating SST[%li]: %#llx %#llx\n", 78 sste - ctx->sstp, slb->vsid, slb->esid); 79 trace_cxl_ste_write(ctx, sste - ctx->sstp, slb->esid, slb->vsid); 80 81 sste->vsid_data = cpu_to_be64(slb->vsid); 82 sste->esid_data = cpu_to_be64(slb->esid); 83 out_unlock: 84 spin_unlock_irqrestore(&ctx->sste_lock, flags); 85 } 86 87 static int cxl_fault_segment(struct cxl_context *ctx, struct mm_struct *mm, 88 u64 ea) 89 { 90 struct copro_slb slb = {0,0}; 91 int rc; 92 93 if (!(rc = copro_calculate_slb(mm, ea, &slb))) { 94 cxl_load_segment(ctx, &slb); 95 } 96 97 return rc; 98 } 99 100 static void cxl_ack_ae(struct cxl_context *ctx) 101 { 102 unsigned long flags; 103 104 cxl_ack_irq(ctx, CXL_PSL_TFC_An_AE, 0); 105 106 spin_lock_irqsave(&ctx->lock, flags); 107 ctx->pending_fault = true; 108 ctx->fault_addr = ctx->dar; 109 ctx->fault_dsisr = ctx->dsisr; 110 spin_unlock_irqrestore(&ctx->lock, flags); 111 112 wake_up_all(&ctx->wq); 113 } 114 115 static int cxl_handle_segment_miss(struct cxl_context *ctx, 116 struct mm_struct *mm, u64 ea) 117 { 118 int rc; 119 120 pr_devel("CXL interrupt: Segment fault pe: %i ea: %#llx\n", ctx->pe, ea); 121 trace_cxl_ste_miss(ctx, ea); 122 123 if ((rc = cxl_fault_segment(ctx, mm, ea))) 124 cxl_ack_ae(ctx); 125 else { 126 127 mb(); /* Order seg table write to TFC MMIO write */ 128 cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0); 129 } 130 131 return IRQ_HANDLED; 132 } 133 134 static void cxl_handle_page_fault(struct cxl_context *ctx, 135 struct mm_struct *mm, u64 dsisr, u64 dar) 136 { 137 unsigned flt = 0; 138 int result; 139 unsigned long access, flags, inv_flags = 0; 140 141 trace_cxl_pte_miss(ctx, dsisr, dar); 142 143 if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) { 144 pr_devel("copro_handle_mm_fault failed: %#x\n", result); 145 return cxl_ack_ae(ctx); 146 } 147 148 /* 149 * update_mmu_cache() will not have loaded the hash since current->trap 150 * is not a 0x400 or 0x300, so just call hash_page_mm() here. 151 */ 152 access = _PAGE_PRESENT; 153 if (dsisr & CXL_PSL_DSISR_An_S) 154 access |= _PAGE_RW; 155 if ((!ctx->kernel) || ~(dar & (1ULL << 63))) 156 access |= _PAGE_USER; 157 158 if (dsisr & DSISR_NOHPTE) 159 inv_flags |= HPTE_NOHPTE_UPDATE; 160 161 local_irq_save(flags); 162 hash_page_mm(mm, dar, access, 0x300, inv_flags); 163 local_irq_restore(flags); 164 165 pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe); 166 cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0); 167 } 168 169 void cxl_handle_fault(struct work_struct *fault_work) 170 { 171 struct cxl_context *ctx = 172 container_of(fault_work, struct cxl_context, fault_work); 173 u64 dsisr = ctx->dsisr; 174 u64 dar = ctx->dar; 175 struct task_struct *task = NULL; 176 struct mm_struct *mm = NULL; 177 178 if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr || 179 cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar || 180 cxl_p2n_read(ctx->afu, CXL_PSL_PEHandle_An) != ctx->pe) { 181 /* Most likely explanation is harmless - a dedicated process 182 * has detached and these were cleared by the PSL purge, but 183 * warn about it just in case */ 184 dev_notice(&ctx->afu->dev, "cxl_handle_fault: Translation fault regs changed\n"); 185 return; 186 } 187 188 /* Early return if the context is being / has been detached */ 189 if (ctx->status == CLOSED) { 190 cxl_ack_ae(ctx); 191 return; 192 } 193 194 pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. " 195 "DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar); 196 197 if (!ctx->kernel) { 198 if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) { 199 pr_devel("cxl_handle_fault unable to get task %i\n", 200 pid_nr(ctx->pid)); 201 cxl_ack_ae(ctx); 202 return; 203 } 204 if (!(mm = get_task_mm(task))) { 205 pr_devel("cxl_handle_fault unable to get mm %i\n", 206 pid_nr(ctx->pid)); 207 cxl_ack_ae(ctx); 208 goto out; 209 } 210 } 211 212 if (dsisr & CXL_PSL_DSISR_An_DS) 213 cxl_handle_segment_miss(ctx, mm, dar); 214 else if (dsisr & CXL_PSL_DSISR_An_DM) 215 cxl_handle_page_fault(ctx, mm, dsisr, dar); 216 else 217 WARN(1, "cxl_handle_fault has nothing to handle\n"); 218 219 if (mm) 220 mmput(mm); 221 out: 222 if (task) 223 put_task_struct(task); 224 } 225 226 static void cxl_prefault_one(struct cxl_context *ctx, u64 ea) 227 { 228 int rc; 229 struct task_struct *task; 230 struct mm_struct *mm; 231 232 if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) { 233 pr_devel("cxl_prefault_one unable to get task %i\n", 234 pid_nr(ctx->pid)); 235 return; 236 } 237 if (!(mm = get_task_mm(task))) { 238 pr_devel("cxl_prefault_one unable to get mm %i\n", 239 pid_nr(ctx->pid)); 240 put_task_struct(task); 241 return; 242 } 243 244 rc = cxl_fault_segment(ctx, mm, ea); 245 246 mmput(mm); 247 put_task_struct(task); 248 } 249 250 static u64 next_segment(u64 ea, u64 vsid) 251 { 252 if (vsid & SLB_VSID_B_1T) 253 ea |= (1ULL << 40) - 1; 254 else 255 ea |= (1ULL << 28) - 1; 256 257 return ea + 1; 258 } 259 260 static void cxl_prefault_vma(struct cxl_context *ctx) 261 { 262 u64 ea, last_esid = 0; 263 struct copro_slb slb; 264 struct vm_area_struct *vma; 265 int rc; 266 struct task_struct *task; 267 struct mm_struct *mm; 268 269 if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) { 270 pr_devel("cxl_prefault_vma unable to get task %i\n", 271 pid_nr(ctx->pid)); 272 return; 273 } 274 if (!(mm = get_task_mm(task))) { 275 pr_devel("cxl_prefault_vm unable to get mm %i\n", 276 pid_nr(ctx->pid)); 277 goto out1; 278 } 279 280 down_read(&mm->mmap_sem); 281 for (vma = mm->mmap; vma; vma = vma->vm_next) { 282 for (ea = vma->vm_start; ea < vma->vm_end; 283 ea = next_segment(ea, slb.vsid)) { 284 rc = copro_calculate_slb(mm, ea, &slb); 285 if (rc) 286 continue; 287 288 if (last_esid == slb.esid) 289 continue; 290 291 cxl_load_segment(ctx, &slb); 292 last_esid = slb.esid; 293 } 294 } 295 up_read(&mm->mmap_sem); 296 297 mmput(mm); 298 out1: 299 put_task_struct(task); 300 } 301 302 void cxl_prefault(struct cxl_context *ctx, u64 wed) 303 { 304 switch (ctx->afu->prefault_mode) { 305 case CXL_PREFAULT_WED: 306 cxl_prefault_one(ctx, wed); 307 break; 308 case CXL_PREFAULT_ALL: 309 cxl_prefault_vma(ctx); 310 break; 311 default: 312 break; 313 } 314 } 315