The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/x86/iommu/busdma_dmar.c

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    1 /*-
    2  * Copyright (c) 2013 The FreeBSD Foundation
    3  * All rights reserved.
    4  *
    5  * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
    6  * under sponsorship from the FreeBSD Foundation.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: releng/11.0/sys/x86/iommu/busdma_dmar.c 284869 2015-06-26 07:01:29Z kib $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/malloc.h>
   36 #include <sys/bus.h>
   37 #include <sys/conf.h>
   38 #include <sys/interrupt.h>
   39 #include <sys/kernel.h>
   40 #include <sys/ktr.h>
   41 #include <sys/lock.h>
   42 #include <sys/proc.h>
   43 #include <sys/memdesc.h>
   44 #include <sys/mutex.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/rman.h>
   47 #include <sys/taskqueue.h>
   48 #include <sys/tree.h>
   49 #include <sys/uio.h>
   50 #include <sys/vmem.h>
   51 #include <dev/pci/pcireg.h>
   52 #include <dev/pci/pcivar.h>
   53 #include <vm/vm.h>
   54 #include <vm/vm_extern.h>
   55 #include <vm/vm_kern.h>
   56 #include <vm/vm_object.h>
   57 #include <vm/vm_page.h>
   58 #include <vm/vm_map.h>
   59 #include <machine/atomic.h>
   60 #include <machine/bus.h>
   61 #include <machine/md_var.h>
   62 #include <machine/specialreg.h>
   63 #include <x86/include/busdma_impl.h>
   64 #include <x86/iommu/intel_reg.h>
   65 #include <x86/iommu/busdma_dmar.h>
   66 #include <x86/iommu/intel_dmar.h>
   67 
   68 /*
   69  * busdma_dmar.c, the implementation of the busdma(9) interface using
   70  * DMAR units from Intel VT-d.
   71  */
   72 
   73 static bool
   74 dmar_bus_dma_is_dev_disabled(int domain, int bus, int slot, int func)
   75 {
   76         char str[128], *env;
   77 
   78         snprintf(str, sizeof(str), "hw.busdma.pci%d.%d.%d.%d.bounce",
   79             domain, bus, slot, func);
   80         env = kern_getenv(str);
   81         if (env == NULL)
   82                 return (false);
   83         freeenv(env);
   84         return (true);
   85 }
   86 
   87 /*
   88  * Given original device, find the requester ID that will be seen by
   89  * the DMAR unit and used for page table lookup.  PCI bridges may take
   90  * ownership of transactions from downstream devices, so it may not be
   91  * the same as the BSF of the target device.  In those cases, all
   92  * devices downstream of the bridge must share a single mapping
   93  * domain, and must collectively be assigned to use either DMAR or
   94  * bounce mapping.
   95  */
   96 device_t
   97 dmar_get_requester(device_t dev, uint16_t *rid)
   98 {
   99         devclass_t pci_class;
  100         device_t l, pci, pcib, pcip, pcibp, requester;
  101         int cap_offset;
  102         uint16_t pcie_flags;
  103         bool bridge_is_pcie;
  104 
  105         pci_class = devclass_find("pci");
  106         l = requester = dev;
  107 
  108         *rid = pci_get_rid(dev);
  109 
  110         /*
  111          * Walk the bridge hierarchy from the target device to the
  112          * host port to find the translating bridge nearest the DMAR
  113          * unit.
  114          */
  115         for (;;) {
  116                 pci = device_get_parent(l);
  117                 KASSERT(pci != NULL, ("dmar_get_requester(%s): NULL parent "
  118                     "for %s", device_get_name(dev), device_get_name(l)));
  119                 KASSERT(device_get_devclass(pci) == pci_class,
  120                     ("dmar_get_requester(%s): non-pci parent %s for %s",
  121                     device_get_name(dev), device_get_name(pci),
  122                     device_get_name(l)));
  123 
  124                 pcib = device_get_parent(pci);
  125                 KASSERT(pcib != NULL, ("dmar_get_requester(%s): NULL bridge "
  126                     "for %s", device_get_name(dev), device_get_name(pci)));
  127 
  128                 /*
  129                  * The parent of our "bridge" isn't another PCI bus,
  130                  * so pcib isn't a PCI->PCI bridge but rather a host
  131                  * port, and the requester ID won't be translated
  132                  * further.
  133                  */
  134                 pcip = device_get_parent(pcib);
  135                 if (device_get_devclass(pcip) != pci_class)
  136                         break;
  137                 pcibp = device_get_parent(pcip);
  138 
  139                 if (pci_find_cap(l, PCIY_EXPRESS, &cap_offset) == 0) {
  140                         /*
  141                          * Do not stop the loop even if the target
  142                          * device is PCIe, because it is possible (but
  143                          * unlikely) to have a PCI->PCIe bridge
  144                          * somewhere in the hierarchy.
  145                          */
  146                         l = pcib;
  147                 } else {
  148                         /*
  149                          * Device is not PCIe, it cannot be seen as a
  150                          * requester by DMAR unit.  Check whether the
  151                          * bridge is PCIe.
  152                          */
  153                         bridge_is_pcie = pci_find_cap(pcib, PCIY_EXPRESS,
  154                             &cap_offset) == 0;
  155                         requester = pcib;
  156 
  157                         /*
  158                          * Check for a buggy PCIe/PCI bridge that
  159                          * doesn't report the express capability.  If
  160                          * the bridge above it is express but isn't a
  161                          * PCI bridge, then we know pcib is actually a
  162                          * PCIe/PCI bridge.
  163                          */
  164                         if (!bridge_is_pcie && pci_find_cap(pcibp,
  165                             PCIY_EXPRESS, &cap_offset) == 0) {
  166                                 pcie_flags = pci_read_config(pcibp,
  167                                     cap_offset + PCIER_FLAGS, 2);
  168                                 if ((pcie_flags & PCIEM_FLAGS_TYPE) !=
  169                                     PCIEM_TYPE_PCI_BRIDGE)
  170                                         bridge_is_pcie = true;
  171                         }
  172 
  173                         if (bridge_is_pcie) {
  174                                 /*
  175                                  * The current device is not PCIe, but
  176                                  * the bridge above it is.  This is a
  177                                  * PCIe->PCI bridge.  Assume that the
  178                                  * requester ID will be the secondary
  179                                  * bus number with slot and function
  180                                  * set to zero.
  181                                  *
  182                                  * XXX: Doesn't handle the case where
  183                                  * the bridge is PCIe->PCI-X, and the
  184                                  * bridge will only take ownership of
  185                                  * requests in some cases.  We should
  186                                  * provide context entries with the
  187                                  * same page tables for taken and
  188                                  * non-taken transactions.
  189                                  */
  190                                 *rid = PCI_RID(pci_get_bus(l), 0, 0);
  191                                 l = pcibp;
  192                         } else {
  193                                 /*
  194                                  * Neither the device nor the bridge
  195                                  * above it are PCIe.  This is a
  196                                  * conventional PCI->PCI bridge, which
  197                                  * will use the bridge's BSF as the
  198                                  * requester ID.
  199                                  */
  200                                 *rid = pci_get_rid(pcib);
  201                                 l = pcib;
  202                         }
  203                 }
  204         }
  205         return (requester);
  206 }
  207 
  208 struct dmar_ctx *
  209 dmar_instantiate_ctx(struct dmar_unit *dmar, device_t dev, bool rmrr)
  210 {
  211         device_t requester;
  212         struct dmar_ctx *ctx;
  213         bool disabled;
  214         uint16_t rid;
  215 
  216         requester = dmar_get_requester(dev, &rid);
  217 
  218         /*
  219          * If the user requested the IOMMU disabled for the device, we
  220          * cannot disable the DMAR, due to possibility of other
  221          * devices on the same DMAR still requiring translation.
  222          * Instead provide the identity mapping for the device
  223          * context.
  224          */
  225         disabled = dmar_bus_dma_is_dev_disabled(pci_get_domain(requester), 
  226             pci_get_bus(requester), pci_get_slot(requester), 
  227             pci_get_function(requester));
  228         ctx = dmar_get_ctx_for_dev(dmar, requester, rid, disabled, rmrr);
  229         if (ctx == NULL)
  230                 return (NULL);
  231         if (disabled) {
  232                 /*
  233                  * Keep the first reference on context, release the
  234                  * later refs.
  235                  */
  236                 DMAR_LOCK(dmar);
  237                 if ((ctx->flags & DMAR_CTX_DISABLED) == 0) {
  238                         ctx->flags |= DMAR_CTX_DISABLED;
  239                         DMAR_UNLOCK(dmar);
  240                 } else {
  241                         dmar_free_ctx_locked(dmar, ctx);
  242                 }
  243                 ctx = NULL;
  244         }
  245         return (ctx);
  246 }
  247 
  248 bus_dma_tag_t
  249 dmar_get_dma_tag(device_t dev, device_t child)
  250 {
  251         struct dmar_unit *dmar;
  252         struct dmar_ctx *ctx;
  253         bus_dma_tag_t res;
  254 
  255         dmar = dmar_find(child);
  256         /* Not in scope of any DMAR ? */
  257         if (dmar == NULL)
  258                 return (NULL);
  259         if (!dmar->dma_enabled)
  260                 return (NULL);
  261         dmar_quirks_pre_use(dmar);
  262         dmar_instantiate_rmrr_ctxs(dmar);
  263 
  264         ctx = dmar_instantiate_ctx(dmar, child, false);
  265         res = ctx == NULL ? NULL : (bus_dma_tag_t)&ctx->ctx_tag;
  266         return (res);
  267 }
  268 
  269 static MALLOC_DEFINE(M_DMAR_DMAMAP, "dmar_dmamap", "Intel DMAR DMA Map");
  270 
  271 static void dmar_bus_schedule_dmamap(struct dmar_unit *unit,
  272     struct bus_dmamap_dmar *map);
  273 
  274 static int
  275 dmar_bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
  276     bus_addr_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
  277     bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
  278     int nsegments, bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
  279     void *lockfuncarg, bus_dma_tag_t *dmat)
  280 {
  281         struct bus_dma_tag_dmar *newtag, *oldtag;
  282         int error;
  283 
  284         *dmat = NULL;
  285         error = common_bus_dma_tag_create(parent != NULL ?
  286             &((struct bus_dma_tag_dmar *)parent)->common : NULL, alignment,
  287             boundary, lowaddr, highaddr, filter, filterarg, maxsize,
  288             nsegments, maxsegsz, flags, lockfunc, lockfuncarg,
  289             sizeof(struct bus_dma_tag_dmar), (void **)&newtag);
  290         if (error != 0)
  291                 goto out;
  292 
  293         oldtag = (struct bus_dma_tag_dmar *)parent;
  294         newtag->common.impl = &bus_dma_dmar_impl;
  295         newtag->ctx = oldtag->ctx;
  296         newtag->owner = oldtag->owner;
  297 
  298         *dmat = (bus_dma_tag_t)newtag;
  299 out:
  300         CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
  301             __func__, newtag, (newtag != NULL ? newtag->common.flags : 0),
  302             error);
  303         return (error);
  304 }
  305 
  306 static int
  307 dmar_bus_dma_tag_destroy(bus_dma_tag_t dmat1)
  308 {
  309         struct bus_dma_tag_dmar *dmat, *dmat_copy, *parent;
  310         int error;
  311 
  312         error = 0;
  313         dmat_copy = dmat = (struct bus_dma_tag_dmar *)dmat1;
  314 
  315         if (dmat != NULL) {
  316                 if (dmat->map_count != 0) {
  317                         error = EBUSY;
  318                         goto out;
  319                 }
  320                 while (dmat != NULL) {
  321                         parent = (struct bus_dma_tag_dmar *)dmat->common.parent;
  322                         if (atomic_fetchadd_int(&dmat->common.ref_count, -1) ==
  323                             1) {
  324                                 if (dmat == &dmat->ctx->ctx_tag)
  325                                         dmar_free_ctx(dmat->ctx);
  326                                 free(dmat->segments, M_DMAR_DMAMAP);
  327                                 free(dmat, M_DEVBUF);
  328                                 dmat = parent;
  329                         } else
  330                                 dmat = NULL;
  331                 }
  332         }
  333 out:
  334         CTR3(KTR_BUSDMA, "%s tag %p error %d", __func__, dmat_copy, error);
  335         return (error);
  336 }
  337 
  338 static int
  339 dmar_bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
  340 {
  341         struct bus_dma_tag_dmar *tag;
  342         struct bus_dmamap_dmar *map;
  343 
  344         tag = (struct bus_dma_tag_dmar *)dmat;
  345         map = malloc(sizeof(*map), M_DMAR_DMAMAP, M_NOWAIT | M_ZERO);
  346         if (map == NULL) {
  347                 *mapp = NULL;
  348                 return (ENOMEM);
  349         }
  350         if (tag->segments == NULL) {
  351                 tag->segments = malloc(sizeof(bus_dma_segment_t) *
  352                     tag->common.nsegments, M_DMAR_DMAMAP, M_NOWAIT);
  353                 if (tag->segments == NULL) {
  354                         free(map, M_DMAR_DMAMAP);
  355                         *mapp = NULL;
  356                         return (ENOMEM);
  357                 }
  358         }
  359         TAILQ_INIT(&map->map_entries);
  360         map->tag = tag;
  361         map->locked = true;
  362         map->cansleep = false;
  363         tag->map_count++;
  364         *mapp = (bus_dmamap_t)map;
  365 
  366         return (0);
  367 }
  368 
  369 static int
  370 dmar_bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map1)
  371 {
  372         struct bus_dma_tag_dmar *tag;
  373         struct bus_dmamap_dmar *map;
  374         struct dmar_domain *domain;
  375 
  376         tag = (struct bus_dma_tag_dmar *)dmat;
  377         map = (struct bus_dmamap_dmar *)map1;
  378         if (map != NULL) {
  379                 domain = tag->ctx->domain;
  380                 DMAR_DOMAIN_LOCK(domain);
  381                 if (!TAILQ_EMPTY(&map->map_entries)) {
  382                         DMAR_DOMAIN_UNLOCK(domain);
  383                         return (EBUSY);
  384                 }
  385                 DMAR_DOMAIN_UNLOCK(domain);
  386                 free(map, M_DMAR_DMAMAP);
  387         }
  388         tag->map_count--;
  389         return (0);
  390 }
  391 
  392 
  393 static int
  394 dmar_bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  395     bus_dmamap_t *mapp)
  396 {
  397         struct bus_dma_tag_dmar *tag;
  398         struct bus_dmamap_dmar *map;
  399         int error, mflags;
  400         vm_memattr_t attr;
  401 
  402         error = dmar_bus_dmamap_create(dmat, flags, mapp);
  403         if (error != 0)
  404                 return (error);
  405 
  406         mflags = (flags & BUS_DMA_NOWAIT) != 0 ? M_NOWAIT : M_WAITOK;
  407         mflags |= (flags & BUS_DMA_ZERO) != 0 ? M_ZERO : 0;
  408         attr = (flags & BUS_DMA_NOCACHE) != 0 ? VM_MEMATTR_UNCACHEABLE :
  409             VM_MEMATTR_DEFAULT;
  410 
  411         tag = (struct bus_dma_tag_dmar *)dmat;
  412         map = (struct bus_dmamap_dmar *)*mapp;
  413 
  414         if (tag->common.maxsize < PAGE_SIZE &&
  415             tag->common.alignment <= tag->common.maxsize &&
  416             attr == VM_MEMATTR_DEFAULT) {
  417                 *vaddr = malloc(tag->common.maxsize, M_DEVBUF, mflags);
  418                 map->flags |= BUS_DMAMAP_DMAR_MALLOC;
  419         } else {
  420                 *vaddr = (void *)kmem_alloc_attr(kernel_arena,
  421                     tag->common.maxsize, mflags, 0ul, BUS_SPACE_MAXADDR,
  422                     attr);
  423                 map->flags |= BUS_DMAMAP_DMAR_KMEM_ALLOC;
  424         }
  425         if (*vaddr == NULL) {
  426                 dmar_bus_dmamap_destroy(dmat, *mapp);
  427                 *mapp = NULL;
  428                 return (ENOMEM);
  429         }
  430         return (0);
  431 }
  432 
  433 static void
  434 dmar_bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map1)
  435 {
  436         struct bus_dma_tag_dmar *tag;
  437         struct bus_dmamap_dmar *map;
  438 
  439         tag = (struct bus_dma_tag_dmar *)dmat;
  440         map = (struct bus_dmamap_dmar *)map1;
  441 
  442         if ((map->flags & BUS_DMAMAP_DMAR_MALLOC) != 0) {
  443                 free(vaddr, M_DEVBUF);
  444                 map->flags &= ~BUS_DMAMAP_DMAR_MALLOC;
  445         } else {
  446                 KASSERT((map->flags & BUS_DMAMAP_DMAR_KMEM_ALLOC) != 0,
  447                     ("dmar_bus_dmamem_free for non alloced map %p", map));
  448                 kmem_free(kernel_arena, (vm_offset_t)vaddr, tag->common.maxsize);
  449                 map->flags &= ~BUS_DMAMAP_DMAR_KMEM_ALLOC;
  450         }
  451 
  452         dmar_bus_dmamap_destroy(dmat, map1);
  453 }
  454 
  455 static int
  456 dmar_bus_dmamap_load_something1(struct bus_dma_tag_dmar *tag,
  457     struct bus_dmamap_dmar *map, vm_page_t *ma, int offset, bus_size_t buflen,
  458     int flags, bus_dma_segment_t *segs, int *segp,
  459     struct dmar_map_entries_tailq *unroll_list)
  460 {
  461         struct dmar_ctx *ctx;
  462         struct dmar_domain *domain;
  463         struct dmar_map_entry *entry;
  464         dmar_gaddr_t size;
  465         bus_size_t buflen1;
  466         int error, idx, gas_flags, seg;
  467 
  468         KASSERT(offset < DMAR_PAGE_SIZE, ("offset %d", offset));
  469         if (segs == NULL)
  470                 segs = tag->segments;
  471         ctx = tag->ctx;
  472         domain = ctx->domain;
  473         seg = *segp;
  474         error = 0;
  475         idx = 0;
  476         while (buflen > 0) {
  477                 seg++;
  478                 if (seg >= tag->common.nsegments) {
  479                         error = EFBIG;
  480                         break;
  481                 }
  482                 buflen1 = buflen > tag->common.maxsegsz ?
  483                     tag->common.maxsegsz : buflen;
  484                 size = round_page(offset + buflen1);
  485 
  486                 /*
  487                  * (Too) optimistically allow split if there are more
  488                  * then one segments left.
  489                  */
  490                 gas_flags = map->cansleep ? DMAR_GM_CANWAIT : 0;
  491                 if (seg + 1 < tag->common.nsegments)
  492                         gas_flags |= DMAR_GM_CANSPLIT;
  493 
  494                 error = dmar_gas_map(domain, &tag->common, size, offset,
  495                     DMAR_MAP_ENTRY_READ | DMAR_MAP_ENTRY_WRITE,
  496                     gas_flags, ma + idx, &entry);
  497                 if (error != 0)
  498                         break;
  499                 if ((gas_flags & DMAR_GM_CANSPLIT) != 0) {
  500                         KASSERT(size >= entry->end - entry->start,
  501                             ("split increased entry size %jx %jx %jx",
  502                             (uintmax_t)size, (uintmax_t)entry->start,
  503                             (uintmax_t)entry->end));
  504                         size = entry->end - entry->start;
  505                         if (buflen1 > size)
  506                                 buflen1 = size;
  507                 } else {
  508                         KASSERT(entry->end - entry->start == size,
  509                             ("no split allowed %jx %jx %jx",
  510                             (uintmax_t)size, (uintmax_t)entry->start,
  511                             (uintmax_t)entry->end));
  512                 }
  513                 if (offset + buflen1 > size)
  514                         buflen1 = size - offset;
  515                 if (buflen1 > tag->common.maxsegsz)
  516                         buflen1 = tag->common.maxsegsz;
  517 
  518                 KASSERT(((entry->start + offset) & (tag->common.alignment - 1))
  519                     == 0,
  520                     ("alignment failed: ctx %p start 0x%jx offset %x "
  521                     "align 0x%jx", ctx, (uintmax_t)entry->start, offset,
  522                     (uintmax_t)tag->common.alignment));
  523                 KASSERT(entry->end <= tag->common.lowaddr ||
  524                     entry->start >= tag->common.highaddr,
  525                     ("entry placement failed: ctx %p start 0x%jx end 0x%jx "
  526                     "lowaddr 0x%jx highaddr 0x%jx", ctx,
  527                     (uintmax_t)entry->start, (uintmax_t)entry->end,
  528                     (uintmax_t)tag->common.lowaddr,
  529                     (uintmax_t)tag->common.highaddr));
  530                 KASSERT(dmar_test_boundary(entry->start + offset, buflen1,
  531                     tag->common.boundary),
  532                     ("boundary failed: ctx %p start 0x%jx end 0x%jx "
  533                     "boundary 0x%jx", ctx, (uintmax_t)entry->start,
  534                     (uintmax_t)entry->end, (uintmax_t)tag->common.boundary));
  535                 KASSERT(buflen1 <= tag->common.maxsegsz,
  536                     ("segment too large: ctx %p start 0x%jx end 0x%jx "
  537                     "buflen1 0x%jx maxsegsz 0x%jx", ctx,
  538                     (uintmax_t)entry->start, (uintmax_t)entry->end,
  539                     (uintmax_t)buflen1, (uintmax_t)tag->common.maxsegsz));
  540 
  541                 DMAR_DOMAIN_LOCK(domain);
  542                 TAILQ_INSERT_TAIL(&map->map_entries, entry, dmamap_link);
  543                 entry->flags |= DMAR_MAP_ENTRY_MAP;
  544                 DMAR_DOMAIN_UNLOCK(domain);
  545                 TAILQ_INSERT_TAIL(unroll_list, entry, unroll_link);
  546 
  547                 segs[seg].ds_addr = entry->start + offset;
  548                 segs[seg].ds_len = buflen1;
  549 
  550                 idx += OFF_TO_IDX(trunc_page(offset + buflen1));
  551                 offset += buflen1;
  552                 offset &= DMAR_PAGE_MASK;
  553                 buflen -= buflen1;
  554         }
  555         if (error == 0)
  556                 *segp = seg;
  557         return (error);
  558 }
  559 
  560 static int
  561 dmar_bus_dmamap_load_something(struct bus_dma_tag_dmar *tag,
  562     struct bus_dmamap_dmar *map, vm_page_t *ma, int offset, bus_size_t buflen,
  563     int flags, bus_dma_segment_t *segs, int *segp)
  564 {
  565         struct dmar_ctx *ctx;
  566         struct dmar_domain *domain;
  567         struct dmar_map_entry *entry, *entry1;
  568         struct dmar_map_entries_tailq unroll_list;
  569         int error;
  570 
  571         ctx = tag->ctx;
  572         domain = ctx->domain;
  573         atomic_add_long(&ctx->loads, 1);
  574 
  575         TAILQ_INIT(&unroll_list);
  576         error = dmar_bus_dmamap_load_something1(tag, map, ma, offset,
  577             buflen, flags, segs, segp, &unroll_list);
  578         if (error != 0) {
  579                 /*
  580                  * The busdma interface does not allow us to report
  581                  * partial buffer load, so unfortunately we have to
  582                  * revert all work done.
  583                  */
  584                 DMAR_DOMAIN_LOCK(domain);
  585                 TAILQ_FOREACH_SAFE(entry, &unroll_list, unroll_link,
  586                     entry1) {
  587                         /*
  588                          * No entries other than what we have created
  589                          * during the failed run might have been
  590                          * inserted there in between, since we own ctx
  591                          * pglock.
  592                          */
  593                         TAILQ_REMOVE(&map->map_entries, entry, dmamap_link);
  594                         TAILQ_REMOVE(&unroll_list, entry, unroll_link);
  595                         TAILQ_INSERT_TAIL(&domain->unload_entries, entry,
  596                             dmamap_link);
  597                 }
  598                 DMAR_DOMAIN_UNLOCK(domain);
  599                 taskqueue_enqueue(domain->dmar->delayed_taskqueue,
  600                     &domain->unload_task);
  601         }
  602 
  603         if (error == ENOMEM && (flags & BUS_DMA_NOWAIT) == 0 &&
  604             !map->cansleep)
  605                 error = EINPROGRESS;
  606         if (error == EINPROGRESS)
  607                 dmar_bus_schedule_dmamap(domain->dmar, map);
  608         return (error);
  609 }
  610 
  611 static int
  612 dmar_bus_dmamap_load_ma(bus_dma_tag_t dmat, bus_dmamap_t map1,
  613     struct vm_page **ma, bus_size_t tlen, int ma_offs, int flags,
  614     bus_dma_segment_t *segs, int *segp)
  615 {
  616         struct bus_dma_tag_dmar *tag;
  617         struct bus_dmamap_dmar *map;
  618 
  619         tag = (struct bus_dma_tag_dmar *)dmat;
  620         map = (struct bus_dmamap_dmar *)map1;
  621         return (dmar_bus_dmamap_load_something(tag, map, ma, ma_offs, tlen,
  622             flags, segs, segp));
  623 }
  624 
  625 static int
  626 dmar_bus_dmamap_load_phys(bus_dma_tag_t dmat, bus_dmamap_t map1,
  627     vm_paddr_t buf, bus_size_t buflen, int flags, bus_dma_segment_t *segs,
  628     int *segp)
  629 {
  630         struct bus_dma_tag_dmar *tag;
  631         struct bus_dmamap_dmar *map;
  632         vm_page_t *ma;
  633         vm_paddr_t pstart, pend;
  634         int error, i, ma_cnt, offset;
  635 
  636         tag = (struct bus_dma_tag_dmar *)dmat;
  637         map = (struct bus_dmamap_dmar *)map1;
  638         pstart = trunc_page(buf);
  639         pend = round_page(buf + buflen);
  640         offset = buf & PAGE_MASK;
  641         ma_cnt = OFF_TO_IDX(pend - pstart);
  642         ma = malloc(sizeof(vm_page_t) * ma_cnt, M_DEVBUF, map->cansleep ?
  643             M_WAITOK : M_NOWAIT);
  644         if (ma == NULL)
  645                 return (ENOMEM);
  646         for (i = 0; i < ma_cnt; i++)
  647                 ma[i] = PHYS_TO_VM_PAGE(pstart + i * PAGE_SIZE);
  648         error = dmar_bus_dmamap_load_something(tag, map, ma, offset, buflen,
  649             flags, segs, segp);
  650         free(ma, M_DEVBUF);
  651         return (error);
  652 }
  653 
  654 static int
  655 dmar_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map1, void *buf,
  656     bus_size_t buflen, pmap_t pmap, int flags, bus_dma_segment_t *segs,
  657     int *segp)
  658 {
  659         struct bus_dma_tag_dmar *tag;
  660         struct bus_dmamap_dmar *map;
  661         vm_page_t *ma, fma;
  662         vm_paddr_t pstart, pend, paddr;
  663         int error, i, ma_cnt, offset;
  664 
  665         tag = (struct bus_dma_tag_dmar *)dmat;
  666         map = (struct bus_dmamap_dmar *)map1;
  667         pstart = trunc_page((vm_offset_t)buf);
  668         pend = round_page((vm_offset_t)buf + buflen);
  669         offset = (vm_offset_t)buf & PAGE_MASK;
  670         ma_cnt = OFF_TO_IDX(pend - pstart);
  671         ma = malloc(sizeof(vm_page_t) * ma_cnt, M_DEVBUF, map->cansleep ?
  672             M_WAITOK : M_NOWAIT);
  673         if (ma == NULL)
  674                 return (ENOMEM);
  675         if (dumping) {
  676                 /*
  677                  * If dumping, do not attempt to call
  678                  * PHYS_TO_VM_PAGE() at all.  It may return non-NULL
  679                  * but the vm_page returned might be not initialized,
  680                  * e.g. for the kernel itself.
  681                  */
  682                 KASSERT(pmap == kernel_pmap, ("non-kernel address write"));
  683                 fma = malloc(sizeof(struct vm_page) * ma_cnt, M_DEVBUF,
  684                     M_ZERO | (map->cansleep ? M_WAITOK : M_NOWAIT));
  685                 if (fma == NULL) {
  686                         free(ma, M_DEVBUF);
  687                         return (ENOMEM);
  688                 }
  689                 for (i = 0; i < ma_cnt; i++, pstart += PAGE_SIZE) {
  690                         paddr = pmap_kextract(pstart);
  691                         vm_page_initfake(&fma[i], paddr, VM_MEMATTR_DEFAULT);
  692                         ma[i] = &fma[i];
  693                 }
  694         } else {
  695                 fma = NULL;
  696                 for (i = 0; i < ma_cnt; i++, pstart += PAGE_SIZE) {
  697                         if (pmap == kernel_pmap)
  698                                 paddr = pmap_kextract(pstart);
  699                         else
  700                                 paddr = pmap_extract(pmap, pstart);
  701                         ma[i] = PHYS_TO_VM_PAGE(paddr);
  702                         KASSERT(VM_PAGE_TO_PHYS(ma[i]) == paddr,
  703                             ("PHYS_TO_VM_PAGE failed %jx %jx m %p",
  704                             (uintmax_t)paddr, (uintmax_t)VM_PAGE_TO_PHYS(ma[i]),
  705                             ma[i]));
  706                 }
  707         }
  708         error = dmar_bus_dmamap_load_something(tag, map, ma, offset, buflen,
  709             flags, segs, segp);
  710         free(ma, M_DEVBUF);
  711         free(fma, M_DEVBUF);
  712         return (error);
  713 }
  714 
  715 static void
  716 dmar_bus_dmamap_waitok(bus_dma_tag_t dmat, bus_dmamap_t map1,
  717     struct memdesc *mem, bus_dmamap_callback_t *callback, void *callback_arg)
  718 {
  719         struct bus_dmamap_dmar *map;
  720 
  721         if (map1 == NULL)
  722                 return;
  723         map = (struct bus_dmamap_dmar *)map1;
  724         map->mem = *mem;
  725         map->tag = (struct bus_dma_tag_dmar *)dmat;
  726         map->callback = callback;
  727         map->callback_arg = callback_arg;
  728 }
  729 
  730 static bus_dma_segment_t *
  731 dmar_bus_dmamap_complete(bus_dma_tag_t dmat, bus_dmamap_t map1,
  732     bus_dma_segment_t *segs, int nsegs, int error)
  733 {
  734         struct bus_dma_tag_dmar *tag;
  735         struct bus_dmamap_dmar *map;
  736 
  737         tag = (struct bus_dma_tag_dmar *)dmat;
  738         map = (struct bus_dmamap_dmar *)map1;
  739 
  740         if (!map->locked) {
  741                 KASSERT(map->cansleep,
  742                     ("map not locked and not sleepable context %p", map));
  743 
  744                 /*
  745                  * We are called from the delayed context.  Relock the
  746                  * driver.
  747                  */
  748                 (tag->common.lockfunc)(tag->common.lockfuncarg, BUS_DMA_LOCK);
  749                 map->locked = true;
  750         }
  751 
  752         if (segs == NULL)
  753                 segs = tag->segments;
  754         return (segs);
  755 }
  756 
  757 /*
  758  * The limitations of busdma KPI forces the dmar to perform the actual
  759  * unload, consisting of the unmapping of the map entries page tables,
  760  * from the delayed context on i386, since page table page mapping
  761  * might require a sleep to be successfull.  The unfortunate
  762  * consequence is that the DMA requests can be served some time after
  763  * the bus_dmamap_unload() call returned.
  764  *
  765  * On amd64, we assume that sf allocation cannot fail.
  766  */
  767 static void
  768 dmar_bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map1)
  769 {
  770         struct bus_dma_tag_dmar *tag;
  771         struct bus_dmamap_dmar *map;
  772         struct dmar_ctx *ctx;
  773         struct dmar_domain *domain;
  774 #if defined(__amd64__)
  775         struct dmar_map_entries_tailq entries;
  776 #endif
  777 
  778         tag = (struct bus_dma_tag_dmar *)dmat;
  779         map = (struct bus_dmamap_dmar *)map1;
  780         ctx = tag->ctx;
  781         domain = ctx->domain;
  782         atomic_add_long(&ctx->unloads, 1);
  783 
  784 #if defined(__i386__)
  785         DMAR_DOMAIN_LOCK(domain);
  786         TAILQ_CONCAT(&domain->unload_entries, &map->map_entries, dmamap_link);
  787         DMAR_DOMAIN_UNLOCK(domain);
  788         taskqueue_enqueue(domain->dmar->delayed_taskqueue,
  789             &domain->unload_task);
  790 #else /* defined(__amd64__) */
  791         TAILQ_INIT(&entries);
  792         DMAR_DOMAIN_LOCK(domain);
  793         TAILQ_CONCAT(&entries, &map->map_entries, dmamap_link);
  794         DMAR_DOMAIN_UNLOCK(domain);
  795         THREAD_NO_SLEEPING();
  796         dmar_domain_unload(domain, &entries, false);
  797         THREAD_SLEEPING_OK();
  798         KASSERT(TAILQ_EMPTY(&entries), ("lazy dmar_ctx_unload %p", ctx));
  799 #endif
  800 }
  801 
  802 static void
  803 dmar_bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map,
  804     bus_dmasync_op_t op)
  805 {
  806 }
  807 
  808 struct bus_dma_impl bus_dma_dmar_impl = {
  809         .tag_create = dmar_bus_dma_tag_create,
  810         .tag_destroy = dmar_bus_dma_tag_destroy,
  811         .map_create = dmar_bus_dmamap_create,
  812         .map_destroy = dmar_bus_dmamap_destroy,
  813         .mem_alloc = dmar_bus_dmamem_alloc,
  814         .mem_free = dmar_bus_dmamem_free,
  815         .load_phys = dmar_bus_dmamap_load_phys,
  816         .load_buffer = dmar_bus_dmamap_load_buffer,
  817         .load_ma = dmar_bus_dmamap_load_ma,
  818         .map_waitok = dmar_bus_dmamap_waitok,
  819         .map_complete = dmar_bus_dmamap_complete,
  820         .map_unload = dmar_bus_dmamap_unload,
  821         .map_sync = dmar_bus_dmamap_sync
  822 };
  823 
  824 static void
  825 dmar_bus_task_dmamap(void *arg, int pending)
  826 {
  827         struct bus_dma_tag_dmar *tag;
  828         struct bus_dmamap_dmar *map;
  829         struct dmar_unit *unit;
  830 
  831         unit = arg;
  832         DMAR_LOCK(unit);
  833         while ((map = TAILQ_FIRST(&unit->delayed_maps)) != NULL) {
  834                 TAILQ_REMOVE(&unit->delayed_maps, map, delay_link);
  835                 DMAR_UNLOCK(unit);
  836                 tag = map->tag;
  837                 map->cansleep = true;
  838                 map->locked = false;
  839                 bus_dmamap_load_mem((bus_dma_tag_t)tag, (bus_dmamap_t)map,
  840                     &map->mem, map->callback, map->callback_arg,
  841                     BUS_DMA_WAITOK);
  842                 map->cansleep = false;
  843                 if (map->locked) {
  844                         (tag->common.lockfunc)(tag->common.lockfuncarg,
  845                             BUS_DMA_UNLOCK);
  846                 } else
  847                         map->locked = true;
  848                 map->cansleep = false;
  849                 DMAR_LOCK(unit);
  850         }
  851         DMAR_UNLOCK(unit);
  852 }
  853 
  854 static void
  855 dmar_bus_schedule_dmamap(struct dmar_unit *unit, struct bus_dmamap_dmar *map)
  856 {
  857 
  858         map->locked = false;
  859         DMAR_LOCK(unit);
  860         TAILQ_INSERT_TAIL(&unit->delayed_maps, map, delay_link);
  861         DMAR_UNLOCK(unit);
  862         taskqueue_enqueue(unit->delayed_taskqueue, &unit->dmamap_load_task);
  863 }
  864 
  865 int
  866 dmar_init_busdma(struct dmar_unit *unit)
  867 {
  868 
  869         unit->dma_enabled = 1;
  870         TUNABLE_INT_FETCH("hw.dmar.dma", &unit->dma_enabled);
  871         TAILQ_INIT(&unit->delayed_maps);
  872         TASK_INIT(&unit->dmamap_load_task, 0, dmar_bus_task_dmamap, unit);
  873         unit->delayed_taskqueue = taskqueue_create("dmar", M_WAITOK,
  874             taskqueue_thread_enqueue, &unit->delayed_taskqueue);
  875         taskqueue_start_threads(&unit->delayed_taskqueue, 1, PI_DISK,
  876             "dmar%d busdma taskq", unit->unit);
  877         return (0);
  878 }
  879 
  880 void
  881 dmar_fini_busdma(struct dmar_unit *unit)
  882 {
  883 
  884         if (unit->delayed_taskqueue == NULL)
  885                 return;
  886 
  887         taskqueue_drain(unit->delayed_taskqueue, &unit->dmamap_load_task);
  888         taskqueue_free(unit->delayed_taskqueue);
  889         unit->delayed_taskqueue = NULL;
  890 }

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