drivers/misc/cxl/cxllib.c

   1 /*
   2  * Copyright 2017 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/hugetlb.h>
  11 #include <linux/sched/mm.h>
  12 #include <asm/pnv-pci.h>
  13 #include <misc/cxllib.h>
  14
  15 #include "cxl.h"
  16
  17 #define CXL_INVALID_DRA                 ~0ull
  18 #define CXL_DUMMY_READ_SIZE             128
  19 #define CXL_DUMMY_READ_ALIGN            8
  20 #define CXL_CAPI_WINDOW_START           0x2000000000000ull
  21 #define CXL_CAPI_WINDOW_LOG_SIZE        48
  22 #define CXL_XSL_CONFIG_CURRENT_VERSION  CXL_XSL_CONFIG_VERSION1
  23
  24
  25 bool cxllib_slot_is_supported(struct pci_dev *dev, unsigned long flags)
  26 {
  27         int rc;
  28         u32 phb_index;
  29         u64 chip_id, capp_unit_id;
  30
  31         /* No flags currently supported */
  32         if (flags)
  33                 return false;
  34
  35         if (!cpu_has_feature(CPU_FTR_HVMODE))
  36                 return false;
  37
  38         if (!cxl_is_power9())
  39                 return false;
  40
  41         if (cxl_slot_is_switched(dev))
  42                 return false;
  43
  44         /* on p9, some pci slots are not connected to a CAPP unit */
  45         rc = cxl_calc_capp_routing(dev, &chip_id, &phb_index, &capp_unit_id);
  46         if (rc)
  47                 return false;
  48
  49         return true;
  50 }
  51 EXPORT_SYMBOL_GPL(cxllib_slot_is_supported);
  52
  53 static DEFINE_MUTEX(dra_mutex);
  54 static u64 dummy_read_addr = CXL_INVALID_DRA;
  55
  56 static int allocate_dummy_read_buf(void)
  57 {
  58         u64 buf, vaddr;
  59         size_t buf_size;
  60
  61         /*
  62          * Dummy read buffer is 128-byte long, aligned on a
  63          * 256-byte boundary and we need the physical address.
  64          */
  65         buf_size = CXL_DUMMY_READ_SIZE + (1ull << CXL_DUMMY_READ_ALIGN);
  66         buf = (u64) kzalloc(buf_size, GFP_KERNEL);
  67         if (!buf)
  68                 return -ENOMEM;
  69
  70         vaddr = (buf + (1ull << CXL_DUMMY_READ_ALIGN) - 1) &
  71                                         (~0ull << CXL_DUMMY_READ_ALIGN);
  72
  73         WARN((vaddr + CXL_DUMMY_READ_SIZE) > (buf + buf_size),
  74                 "Dummy read buffer alignment issue");
  75         dummy_read_addr = virt_to_phys((void *) vaddr);
  76         return 0;
  77 }
  78
  79 int cxllib_get_xsl_config(struct pci_dev *dev, struct cxllib_xsl_config *cfg)
  80 {
  81         int rc;
  82         u32 phb_index;
  83         u64 chip_id, capp_unit_id;
  84
  85         if (!cpu_has_feature(CPU_FTR_HVMODE))
  86                 return -EINVAL;
  87
  88         mutex_lock(&dra_mutex);
  89         if (dummy_read_addr == CXL_INVALID_DRA) {
  90                 rc = allocate_dummy_read_buf();
  91                 if (rc) {
  92                         mutex_unlock(&dra_mutex);
  93                         return rc;
  94                 }
  95         }
  96         mutex_unlock(&dra_mutex);
  97
  98         rc = cxl_calc_capp_routing(dev, &chip_id, &phb_index, &capp_unit_id);
  99         if (rc)
 100                 return rc;
 101
 102         rc = cxl_get_xsl9_dsnctl(dev, capp_unit_id, &cfg->dsnctl);
 103         if (rc)
 104                 return rc;
 105
 106         cfg->version  = CXL_XSL_CONFIG_CURRENT_VERSION;
 107         cfg->log_bar_size = CXL_CAPI_WINDOW_LOG_SIZE;
 108         cfg->bar_addr = CXL_CAPI_WINDOW_START;
 109         cfg->dra = dummy_read_addr;
 110         return 0;
 111 }
 112 EXPORT_SYMBOL_GPL(cxllib_get_xsl_config);
 113
 114 int cxllib_switch_phb_mode(struct pci_dev *dev, enum cxllib_mode mode,
 115                         unsigned long flags)
 116 {
 117         int rc = 0;
 118
 119         if (!cpu_has_feature(CPU_FTR_HVMODE))
 120                 return -EINVAL;
 121
 122         switch (mode) {
 123         case CXL_MODE_PCI:
 124                 /*
 125                  * We currently don't support going back to PCI mode
 126                  * However, we'll turn the invalidations off, so that
 127                  * the firmware doesn't have to ack them and can do
 128                  * things like reset, etc.. with no worries.
 129                  * So always return EPERM (can't go back to PCI) or
 130                  * EBUSY if we couldn't even turn off snooping
 131                  */
 132                 rc = pnv_phb_to_cxl_mode(dev, OPAL_PHB_CAPI_MODE_SNOOP_OFF);
 133                 if (rc)
 134                         rc = -EBUSY;
 135                 else
 136                         rc = -EPERM;
 137                 break;
 138         case CXL_MODE_CXL:
 139                 /* DMA only supported on TVT1 for the time being */
 140                 if (flags != CXL_MODE_DMA_TVT1)
 141                         return -EINVAL;
 142                 rc = pnv_phb_to_cxl_mode(dev, OPAL_PHB_CAPI_MODE_DMA_TVT1);
 143                 if (rc)
 144                         return rc;
 145                 rc = pnv_phb_to_cxl_mode(dev, OPAL_PHB_CAPI_MODE_SNOOP_ON);
 146                 break;
 147         default:
 148                 rc = -EINVAL;
 149         }
 150         return rc;
 151 }
 152 EXPORT_SYMBOL_GPL(cxllib_switch_phb_mode);
 153
 154 /*
 155  * When switching the PHB to capi mode, the TVT#1 entry for
 156  * the Partitionable Endpoint is set in bypass mode, like
 157  * in PCI mode.
 158  * Configure the device dma to use TVT#1, which is done
 159  * by calling dma_set_mask() with a mask large enough.
 160  */
 161 int cxllib_set_device_dma(struct pci_dev *dev, unsigned long flags)
 162 {
 163         int rc;
 164
 165         if (flags)
 166                 return -EINVAL;
 167
 168         rc = dma_set_mask(&dev->dev, DMA_BIT_MASK(64));
 169         return rc;
 170 }
 171 EXPORT_SYMBOL_GPL(cxllib_set_device_dma);
 172
 173 int cxllib_get_PE_attributes(struct task_struct *task,
 174                              unsigned long translation_mode,
 175                              struct cxllib_pe_attributes *attr)
 176 {
 177         struct mm_struct *mm = NULL;
 178
 179         if (translation_mode != CXL_TRANSLATED_MODE &&
 180                 translation_mode != CXL_REAL_MODE)
 181                 return -EINVAL;
 182
 183         attr->sr = cxl_calculate_sr(false,
 184                                 task == NULL,
 185                                 translation_mode == CXL_REAL_MODE,
 186                                 true);
 187         attr->lpid = mfspr(SPRN_LPID);
 188         if (task) {
 189                 mm = get_task_mm(task);
 190                 if (mm == NULL)
 191                         return -EINVAL;
 192                 /*
 193                  * Caller is keeping a reference on mm_users for as long
 194                  * as XSL uses the memory context
 195                  */
 196                 attr->pid = mm->context.id;
 197                 mmput(mm);
 198                 attr->tid = task->thread.tidr;
 199         } else {
 200                 attr->pid = 0;
 201                 attr->tid = 0;
 202         }
 203         return 0;
 204 }
 205 EXPORT_SYMBOL_GPL(cxllib_get_PE_attributes);
 206
 207 static int get_vma_info(struct mm_struct *mm, u64 addr,
 208                         u64 *vma_start, u64 *vma_end,
 209                         unsigned long *page_size)
 210 {
 211         struct vm_area_struct *vma = NULL;
 212         int rc = 0;
 213
 214         down_read(&mm->mmap_sem);
 215
 216         vma = find_vma(mm, addr);
 217         if (!vma) {
 218                 rc = -EFAULT;
 219                 goto out;
 220         }
 221         *page_size = vma_kernel_pagesize(vma);
 222         *vma_start = vma->vm_start;
 223         *vma_end = vma->vm_end;
 224 out:
 225         up_read(&mm->mmap_sem);
 226         return rc;
 227 }
 228
 229 int cxllib_handle_fault(struct mm_struct *mm, u64 addr, u64 size, u64 flags)
 230 {
 231         int rc;
 232         u64 dar, vma_start, vma_end;
 233         unsigned long page_size;
 234
 235         if (mm == NULL)
 236                 return -EFAULT;
 237
 238         /*
 239          * The buffer we have to process can extend over several pages
 240          * and may also cover several VMAs.
 241          * We iterate over all the pages. The page size could vary
 242          * between VMAs.
 243          */
 244         rc = get_vma_info(mm, addr, &vma_start, &vma_end, &page_size);
 245         if (rc)
 246                 return rc;
 247
 248         for (dar = (addr & ~(page_size - 1)); dar < (addr + size);
 249              dar += page_size) {
 250                 if (dar < vma_start || dar >= vma_end) {
 251                         /*
 252                          * We don't hold the mm->mmap_sem semaphore
 253                          * while iterating, since the semaphore is
 254                          * required by one of the lower-level page
 255                          * fault processing functions and it could
 256                          * create a deadlock.
 257                          *
 258                          * It means the VMAs can be altered between 2
 259                          * loop iterations and we could theoretically
 260                          * miss a page (however unlikely). But that's
 261                          * not really a problem, as the driver will
 262                          * retry access, get another page fault on the
 263                          * missing page and call us again.
 264                          */
 265                         rc = get_vma_info(mm, dar, &vma_start, &vma_end,
 266                                         &page_size);
 267                         if (rc)
 268                                 return rc;
 269                 }
 270
 271                 rc = cxl_handle_mm_fault(mm, flags, dar);
 272                 if (rc)
 273                         return -EFAULT;
 274         }
 275         return 0;
 276 }
 277 EXPORT_SYMBOL_GPL(cxllib_handle_fault);