2 * Copyright 2014 IBM Corp.
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.
10 #include <linux/workqueue.h>
11 #include <linux/sched.h>
12 #include <linux/pid.h>
14 #include <linux/moduleparam.h>
16 #undef MODULE_PARAM_PREFIX
17 #define MODULE_PARAM_PREFIX "cxl" "."
18 #include <asm/current.h>
19 #include <asm/copro.h>
25 static bool sste_matches(struct cxl_sste *sste, struct copro_slb *slb)
27 return ((sste->vsid_data == cpu_to_be64(slb->vsid)) &&
28 (sste->esid_data == cpu_to_be64(slb->esid)));
32 * This finds a free SSTE for the given SLB, or returns NULL if it's already in
35 static struct cxl_sste* find_free_sste(struct cxl_context *ctx,
36 struct copro_slb *slb)
38 struct cxl_sste *primary, *sste, *ret = NULL;
39 unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */
43 if (slb->vsid & SLB_VSID_B_1T)
44 hash = (slb->esid >> SID_SHIFT_1T) & mask;
46 hash = (slb->esid >> SID_SHIFT) & mask;
48 primary = ctx->sstp + (hash << 3);
50 for (entry = 0, sste = primary; entry < 8; entry++, sste++) {
51 if (!ret && !(be64_to_cpu(sste->esid_data) & SLB_ESID_V))
53 if (sste_matches(sste, slb))
59 /* Nothing free, select an entry to cast out */
60 ret = primary + ctx->sst_lru;
61 ctx->sst_lru = (ctx->sst_lru + 1) & 0x7;
66 static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb)
68 /* mask is the group index, we search primary and secondary here. */
69 struct cxl_sste *sste;
72 spin_lock_irqsave(&ctx->sste_lock, flags);
73 sste = find_free_sste(ctx, slb);
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);
81 sste->vsid_data = cpu_to_be64(slb->vsid);
82 sste->esid_data = cpu_to_be64(slb->esid);
84 spin_unlock_irqrestore(&ctx->sste_lock, flags);
87 static int cxl_fault_segment(struct cxl_context *ctx, struct mm_struct *mm,
90 struct copro_slb slb = {0,0};
93 if (!(rc = copro_calculate_slb(mm, ea, &slb))) {
94 cxl_load_segment(ctx, &slb);
100 static void cxl_ack_ae(struct cxl_context *ctx)
104 cxl_ack_irq(ctx, CXL_PSL_TFC_An_AE, 0);
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);
112 wake_up_all(&ctx->wq);
115 static int cxl_handle_segment_miss(struct cxl_context *ctx,
116 struct mm_struct *mm, u64 ea)
120 pr_devel("CXL interrupt: Segment fault pe: %i ea: %#llx\n", ctx->pe, ea);
121 trace_cxl_ste_miss(ctx, ea);
123 if ((rc = cxl_fault_segment(ctx, mm, ea)))
127 mb(); /* Order seg table write to TFC MMIO write */
128 cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
134 static void cxl_handle_page_fault(struct cxl_context *ctx,
135 struct mm_struct *mm, u64 dsisr, u64 dar)
139 unsigned long access, flags, inv_flags = 0;
141 trace_cxl_pte_miss(ctx, dsisr, dar);
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);
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.
152 access = _PAGE_PRESENT;
153 if (dsisr & CXL_PSL_DSISR_An_S)
155 if ((!ctx->kernel) || ~(dar & (1ULL << 63)))
156 access |= _PAGE_USER;
158 if (dsisr & DSISR_NOHPTE)
159 inv_flags |= HPTE_NOHPTE_UPDATE;
161 local_irq_save(flags);
162 hash_page_mm(mm, dar, access, 0x300, inv_flags);
163 local_irq_restore(flags);
165 pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
166 cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
170 * Returns the mm_struct corresponding to the context ctx via ctx->pid
171 * In case the task has exited we use the task group leader accessible
172 * via ctx->glpid to find the next task in the thread group that has a
173 * valid mm_struct associated with it. If a task with valid mm_struct
174 * is found the ctx->pid is updated to use the task struct for subsequent
175 * translations. In case no valid mm_struct is found in the task group to
176 * service the fault a NULL is returned.
178 static struct mm_struct *get_mem_context(struct cxl_context *ctx)
180 struct task_struct *task = NULL;
181 struct mm_struct *mm = NULL;
182 struct pid *old_pid = ctx->pid;
184 if (old_pid == NULL) {
185 pr_warn("%s: Invalid context for pe=%d\n",
190 task = get_pid_task(old_pid, PIDTYPE_PID);
193 * pid_alive may look racy but this saves us from costly
194 * get_task_mm when the task is a zombie. In worst case
195 * we may think a task is alive, which is about to die
196 * but get_task_mm will return NULL.
198 if (task != NULL && pid_alive(task))
199 mm = get_task_mm(task);
201 /* release the task struct that was taken earlier */
203 put_task_struct(task);
205 pr_devel("%s: Context owning pid=%i for pe=%i dead\n",
206 __func__, pid_nr(old_pid), ctx->pe);
209 * If we couldn't find the mm context then use the group
210 * leader to iterate over the task group and find a task
211 * that gives us mm_struct.
213 if (unlikely(mm == NULL && ctx->glpid != NULL)) {
216 task = pid_task(ctx->glpid, PIDTYPE_PID);
219 mm = get_task_mm(task);
221 ctx->pid = get_task_pid(task,
225 task = next_thread(task);
226 } while (task && !thread_group_leader(task));
229 /* check if we switched pid */
230 if (ctx->pid != old_pid) {
232 pr_devel("%s:pe=%i switch pid %i->%i\n",
233 __func__, ctx->pe, pid_nr(old_pid),
236 pr_devel("%s:Cannot find mm for pid=%i\n",
237 __func__, pid_nr(old_pid));
239 /* drop the reference to older pid */
249 void cxl_handle_fault(struct work_struct *fault_work)
251 struct cxl_context *ctx =
252 container_of(fault_work, struct cxl_context, fault_work);
253 u64 dsisr = ctx->dsisr;
255 struct mm_struct *mm = NULL;
257 if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
258 cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar ||
259 cxl_p2n_read(ctx->afu, CXL_PSL_PEHandle_An) != ctx->pe) {
260 /* Most likely explanation is harmless - a dedicated process
261 * has detached and these were cleared by the PSL purge, but
262 * warn about it just in case */
263 dev_notice(&ctx->afu->dev, "cxl_handle_fault: Translation fault regs changed\n");
267 /* Early return if the context is being / has been detached */
268 if (ctx->status == CLOSED) {
273 pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. "
274 "DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
278 mm = get_mem_context(ctx);
279 /* indicates all the thread in task group have exited */
281 pr_devel("%s: unable to get mm for pe=%d pid=%i\n",
282 __func__, ctx->pe, pid_nr(ctx->pid));
286 pr_devel("Handling page fault for pe=%d pid=%i\n",
287 ctx->pe, pid_nr(ctx->pid));
291 if (dsisr & CXL_PSL_DSISR_An_DS)
292 cxl_handle_segment_miss(ctx, mm, dar);
293 else if (dsisr & CXL_PSL_DSISR_An_DM)
294 cxl_handle_page_fault(ctx, mm, dsisr, dar);
296 WARN(1, "cxl_handle_fault has nothing to handle\n");
302 static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
304 struct mm_struct *mm;
306 mm = get_mem_context(ctx);
308 pr_devel("cxl_prefault_one unable to get mm %i\n",
313 cxl_fault_segment(ctx, mm, ea);
318 static u64 next_segment(u64 ea, u64 vsid)
320 if (vsid & SLB_VSID_B_1T)
321 ea |= (1ULL << 40) - 1;
323 ea |= (1ULL << 28) - 1;
328 static void cxl_prefault_vma(struct cxl_context *ctx)
330 u64 ea, last_esid = 0;
331 struct copro_slb slb;
332 struct vm_area_struct *vma;
334 struct mm_struct *mm;
336 mm = get_mem_context(ctx);
338 pr_devel("cxl_prefault_vm unable to get mm %i\n",
343 down_read(&mm->mmap_sem);
344 for (vma = mm->mmap; vma; vma = vma->vm_next) {
345 for (ea = vma->vm_start; ea < vma->vm_end;
346 ea = next_segment(ea, slb.vsid)) {
347 rc = copro_calculate_slb(mm, ea, &slb);
351 if (last_esid == slb.esid)
354 cxl_load_segment(ctx, &slb);
355 last_esid = slb.esid;
358 up_read(&mm->mmap_sem);
363 void cxl_prefault(struct cxl_context *ctx, u64 wed)
365 switch (ctx->afu->prefault_mode) {
366 case CXL_PREFAULT_WED:
367 cxl_prefault_one(ctx, wed);
369 case CXL_PREFAULT_ALL:
370 cxl_prefault_vma(ctx);