eal: avoid invalid power intrinsics API usage
[dpdk.git] / lib / librte_eal / linux / eal_vfio.c
index e079799..0500824 100644 (file)
@@ -18,6 +18,7 @@
 #include "eal_memcfg.h"
 #include "eal_vfio.h"
 #include "eal_private.h"
+#include "eal_internal_cfg.h"
 
 #ifdef VFIO_PRESENT
 
@@ -295,7 +296,7 @@ vfio_open_group_fd(int iommu_group_num)
                                                        strerror(errno));
                                        return -1;
                                }
-                               return 0;
+                               return -ENOENT;
                        }
                        /* noiommu group found */
                }
@@ -320,12 +321,12 @@ vfio_open_group_fd(int iommu_group_num)
                        vfio_group_fd = mp_rep->fds[0];
                } else if (p->result == SOCKET_NO_FD) {
                        RTE_LOG(ERR, EAL, "  bad VFIO group fd\n");
-                       vfio_group_fd = 0;
+                       vfio_group_fd = -ENOENT;
                }
        }
 
        free(mp_reply.msgs);
-       if (vfio_group_fd < 0)
+       if (vfio_group_fd < 0 && vfio_group_fd != -ENOENT)
                RTE_LOG(ERR, EAL, "  cannot request group fd\n");
        return vfio_group_fd;
 }
@@ -381,9 +382,9 @@ vfio_get_group_fd(struct vfio_config *vfio_cfg,
        }
 
        vfio_group_fd = vfio_open_group_fd(iommu_group_num);
-       if (vfio_group_fd <= 0) {
+       if (vfio_group_fd < 0) {
                RTE_LOG(ERR, EAL, "Failed to open group %d\n", iommu_group_num);
-               return -1;
+               return vfio_group_fd;
        }
 
        cur_grp->group_num = iommu_group_num;
@@ -536,17 +537,6 @@ vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
                return;
        }
 
-#ifdef RTE_ARCH_PPC_64
-       ms = rte_mem_virt2memseg(addr, msl);
-       while (cur_len < len) {
-               int idx = rte_fbarray_find_idx(&msl->memseg_arr, ms);
-
-               rte_fbarray_set_free(&msl->memseg_arr, idx);
-               cur_len += ms->len;
-               ++ms;
-       }
-       cur_len = 0;
-#endif
        /* memsegs are contiguous in memory */
        ms = rte_mem_virt2memseg(addr, msl);
 
@@ -607,17 +597,6 @@ vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
                                                iova_expected - iova_start, 0);
                }
        }
-#ifdef RTE_ARCH_PPC_64
-       cur_len = 0;
-       ms = rte_mem_virt2memseg(addr, msl);
-       while (cur_len < len) {
-               int idx = rte_fbarray_find_idx(&msl->memseg_arr, ms);
-
-               rte_fbarray_set_used(&msl->memseg_arr, idx);
-               cur_len += ms->len;
-               ++ms;
-       }
-#endif
 }
 
 static int
@@ -733,11 +712,14 @@ rte_vfio_setup_device(const char *sysfs_base, const char *dev_addr,
 
        /* get the actual group fd */
        vfio_group_fd = rte_vfio_get_group_fd(iommu_group_num);
-       if (vfio_group_fd < 0)
+       if (vfio_group_fd < 0 && vfio_group_fd != -ENOENT)
                return -1;
 
-       /* if group_fd == 0, that means the device isn't managed by VFIO */
-       if (vfio_group_fd == 0) {
+       /*
+        * if vfio_group_fd == -ENOENT, that means the device
+        * isn't managed by VFIO
+        */
+       if (vfio_group_fd == -ENOENT) {
                RTE_LOG(WARNING, EAL, " %s not managed by VFIO driver, skipping\n",
                                dev_addr);
                return 1;
@@ -975,10 +957,10 @@ rte_vfio_release_device(const char *sysfs_base, const char *dev_addr,
 
        /* get the actual group fd */
        vfio_group_fd = rte_vfio_get_group_fd(iommu_group_num);
-       if (vfio_group_fd <= 0) {
+       if (vfio_group_fd < 0) {
                RTE_LOG(INFO, EAL, "rte_vfio_get_group_fd failed for %s\n",
                                   dev_addr);
-               ret = -1;
+               ret = vfio_group_fd;
                goto out;
        }
 
@@ -1433,21 +1415,30 @@ vfio_type1_dma_map(int vfio_container_fd)
        return rte_memseg_walk(type1_map, &vfio_container_fd);
 }
 
+/* Track the size of the statically allocated DMA window for SPAPR */
+uint64_t spapr_dma_win_len;
+uint64_t spapr_dma_win_page_sz;
+
 static int
 vfio_spapr_dma_do_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
                uint64_t len, int do_map)
 {
-       struct vfio_iommu_type1_dma_map dma_map;
-       struct vfio_iommu_type1_dma_unmap dma_unmap;
-       int ret;
        struct vfio_iommu_spapr_register_memory reg = {
                .argsz = sizeof(reg),
+               .vaddr = (uintptr_t) vaddr,
+               .size = len,
                .flags = 0
        };
-       reg.vaddr = (uintptr_t) vaddr;
-       reg.size = len;
+       int ret;
 
        if (do_map != 0) {
+               struct vfio_iommu_type1_dma_map dma_map;
+
+               if (iova + len > spapr_dma_win_len) {
+                       RTE_LOG(ERR, EAL, "  dma map attempt outside DMA window\n");
+                       return -1;
+               }
+
                ret = ioctl(vfio_container_fd,
                                VFIO_IOMMU_SPAPR_REGISTER_MEMORY, &reg);
                if (ret) {
@@ -1466,24 +1457,14 @@ vfio_spapr_dma_do_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
 
                ret = ioctl(vfio_container_fd, VFIO_IOMMU_MAP_DMA, &dma_map);
                if (ret) {
-                       /**
-                        * In case the mapping was already done EBUSY will be
-                        * returned from kernel.
-                        */
-                       if (errno == EBUSY) {
-                               RTE_LOG(DEBUG, EAL,
-                                       " Memory segment is already mapped,"
-                                       " skipping");
-                       } else {
-                               RTE_LOG(ERR, EAL,
-                                       "  cannot set up DMA remapping,"
-                                       " error %i (%s)\n", errno,
-                                       strerror(errno));
-                               return -1;
-                       }
+                       RTE_LOG(ERR, EAL, "  cannot map vaddr for IOMMU, error %i (%s)\n",
+                               errno, strerror(errno));
+                       return -1;
                }
 
        } else {
+               struct vfio_iommu_type1_dma_map dma_unmap;
+
                memset(&dma_unmap, 0, sizeof(dma_unmap));
                dma_unmap.argsz = sizeof(struct vfio_iommu_type1_dma_unmap);
                dma_unmap.size = len;
@@ -1492,8 +1473,8 @@ vfio_spapr_dma_do_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
                ret = ioctl(vfio_container_fd, VFIO_IOMMU_UNMAP_DMA,
                                &dma_unmap);
                if (ret) {
-                       RTE_LOG(ERR, EAL, "  cannot clear DMA remapping, error %i (%s)\n",
-                                       errno, strerror(errno));
+                       RTE_LOG(ERR, EAL, "  cannot unmap vaddr for IOMMU, error %i (%s)\n",
+                               errno, strerror(errno));
                        return -1;
                }
 
@@ -1501,12 +1482,12 @@ vfio_spapr_dma_do_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
                                VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY, &reg);
                if (ret) {
                        RTE_LOG(ERR, EAL, "  cannot unregister vaddr for IOMMU, error %i (%s)\n",
-                                       errno, strerror(errno));
+                               errno, strerror(errno));
                        return -1;
                }
        }
 
-       return 0;
+       return ret;
 }
 
 static int
@@ -1523,251 +1504,257 @@ vfio_spapr_map_walk(const struct rte_memseg_list *msl,
        if (ms->iova == RTE_BAD_IOVA)
                return 0;
 
-       return vfio_spapr_dma_do_map(*vfio_container_fd, ms->addr_64, ms->iova,
-                       ms->len, 1);
+       return vfio_spapr_dma_do_map(*vfio_container_fd,
+               ms->addr_64, ms->iova, ms->len, 1);
 }
 
+struct spapr_size_walk_param {
+       uint64_t max_va;
+       uint64_t page_sz;
+       bool is_user_managed;
+};
+
+/*
+ * In order to set the DMA window size required for the SPAPR IOMMU
+ * we need to walk the existing virtual memory allocations as well as
+ * find the hugepage size used.
+ */
 static int
-vfio_spapr_unmap_walk(const struct rte_memseg_list *msl,
-               const struct rte_memseg *ms, void *arg)
+vfio_spapr_size_walk(const struct rte_memseg_list *msl, void *arg)
 {
-       int *vfio_container_fd = arg;
+       struct spapr_size_walk_param *param = arg;
+       uint64_t max = (uint64_t) msl->base_va + (uint64_t) msl->len;
 
-       /* skip external memory that isn't a heap */
-       if (msl->external && !msl->heap)
+       if (msl->external && !msl->heap) {
+               /* ignore user managed external memory */
+               param->is_user_managed = true;
                return 0;
+       }
 
-       /* skip any segments with invalid IOVA addresses */
-       if (ms->iova == RTE_BAD_IOVA)
-               return 0;
+       if (max > param->max_va) {
+               param->page_sz = msl->page_sz;
+               param->max_va = max;
+       }
 
-       return vfio_spapr_dma_do_map(*vfio_container_fd, ms->addr_64, ms->iova,
-                       ms->len, 0);
+       return 0;
 }
 
-struct spapr_walk_param {
-       uint64_t window_size;
-       uint64_t hugepage_sz;
-};
-
+/*
+ * Find the highest memory address used in physical or virtual address
+ * space and use that as the top of the DMA window.
+ */
 static int
-vfio_spapr_window_size_walk(const struct rte_memseg_list *msl,
-               const struct rte_memseg *ms, void *arg)
+find_highest_mem_addr(struct spapr_size_walk_param *param)
 {
-       struct spapr_walk_param *param = arg;
-       uint64_t max = ms->iova + ms->len;
+       /* find the maximum IOVA address for setting the DMA window size */
+       if (rte_eal_iova_mode() == RTE_IOVA_PA) {
+               static const char proc_iomem[] = "/proc/iomem";
+               static const char str_sysram[] = "System RAM";
+               uint64_t start, end, max = 0;
+               char *line = NULL;
+               char *dash, *space;
+               size_t line_len;
 
-       /* skip external memory that isn't a heap */
-       if (msl->external && !msl->heap)
+               /*
+                * Example "System RAM" in /proc/iomem:
+                * 00000000-1fffffffff : System RAM
+                * 200000000000-201fffffffff : System RAM
+                */
+               FILE *fd = fopen(proc_iomem, "r");
+               if (fd == NULL) {
+                       RTE_LOG(ERR, EAL, "Cannot open %s\n", proc_iomem);
+                       return -1;
+               }
+               /* Scan /proc/iomem for the highest PA in the system */
+               while (getline(&line, &line_len, fd) != -1) {
+                       if (strstr(line, str_sysram) == NULL)
+                               continue;
+
+                       space = strstr(line, " ");
+                       dash = strstr(line, "-");
+
+                       /* Validate the format of the memory string */
+                       if (space == NULL || dash == NULL || space < dash) {
+                               RTE_LOG(ERR, EAL, "Can't parse line \"%s\" in file %s\n",
+                                       line, proc_iomem);
+                               continue;
+                       }
+
+                       start = strtoull(line, NULL, 16);
+                       end   = strtoull(dash + 1, NULL, 16);
+                       RTE_LOG(DEBUG, EAL, "Found system RAM from 0x%" PRIx64
+                               " to 0x%" PRIx64 "\n", start, end);
+                       if (end > max)
+                               max = end;
+               }
+               free(line);
+               fclose(fd);
+
+               if (max == 0) {
+                       RTE_LOG(ERR, EAL, "Failed to find valid \"System RAM\" "
+                               "entry in file %s\n", proc_iomem);
+                       return -1;
+               }
+
+               spapr_dma_win_len = rte_align64pow2(max + 1);
                return 0;
+       } else if (rte_eal_iova_mode() == RTE_IOVA_VA) {
+               RTE_LOG(DEBUG, EAL, "Highest VA address in memseg list is 0x%"
+                       PRIx64 "\n", param->max_va);
+               spapr_dma_win_len = rte_align64pow2(param->max_va);
+               return 0;
+       }
 
-       /* skip any segments with invalid IOVA addresses */
-       if (ms->iova == RTE_BAD_IOVA)
+       spapr_dma_win_len = 0;
+       RTE_LOG(ERR, EAL, "Unsupported IOVA mode\n");
+       return -1;
+}
+
+
+/*
+ * The SPAPRv2 IOMMU supports 2 DMA windows with starting
+ * address at 0 or 1<<59.  By default, a DMA window is set
+ * at address 0, 2GB long, with a 4KB page.  For DPDK we
+ * must remove the default window and setup a new DMA window
+ * based on the hugepage size and memory requirements of
+ * the application before we can map memory for DMA.
+ */
+static int
+spapr_dma_win_size(void)
+{
+       struct spapr_size_walk_param param;
+
+       /* only create DMA window once */
+       if (spapr_dma_win_len > 0)
                return 0;
 
-       if (max > param->window_size) {
-               param->hugepage_sz = ms->hugepage_sz;
-               param->window_size = max;
+       /* walk the memseg list to find the page size/max VA address */
+       memset(&param, 0, sizeof(param));
+       if (rte_memseg_list_walk(vfio_spapr_size_walk, &param) < 0) {
+               RTE_LOG(ERR, EAL, "Failed to walk memseg list for DMA window size\n");
+               return -1;
        }
 
+       /* we can't be sure if DMA window covers external memory */
+       if (param.is_user_managed)
+               RTE_LOG(WARNING, EAL, "Detected user managed external memory which may not be managed by the IOMMU\n");
+
+       /* check physical/virtual memory size */
+       if (find_highest_mem_addr(&param) < 0)
+               return -1;
+       RTE_LOG(DEBUG, EAL, "Setting DMA window size to 0x%" PRIx64 "\n",
+               spapr_dma_win_len);
+       spapr_dma_win_page_sz = param.page_sz;
+       rte_mem_set_dma_mask(__builtin_ctzll(spapr_dma_win_len));
        return 0;
 }
 
 static int
-vfio_spapr_create_new_dma_window(int vfio_container_fd,
-               struct vfio_iommu_spapr_tce_create *create) {
+vfio_spapr_create_dma_window(int vfio_container_fd)
+{
+       struct vfio_iommu_spapr_tce_create create = {
+               .argsz = sizeof(create), };
        struct vfio_iommu_spapr_tce_remove remove = {
-               .argsz = sizeof(remove),
-       };
+               .argsz = sizeof(remove), };
        struct vfio_iommu_spapr_tce_info info = {
-               .argsz = sizeof(info),
-       };
+               .argsz = sizeof(info), };
        int ret;
 
-       /* query spapr iommu info */
+       ret = spapr_dma_win_size();
+       if (ret < 0)
+               return ret;
+
        ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &info);
        if (ret) {
-               RTE_LOG(ERR, EAL, "  cannot get iommu info, "
-                               "error %i (%s)\n", errno, strerror(errno));
+               RTE_LOG(ERR, EAL, "  can't get iommu info, error %i (%s)\n",
+                       errno, strerror(errno));
                return -1;
        }
 
-       /* remove default DMA of 32 bit window */
+       /*
+        * sPAPR v1/v2 IOMMU always has a default 1G DMA window set.  The window
+        * can't be changed for v1 but it can be changed for v2. Since DPDK only
+        * supports v2, remove the default DMA window so it can be resized.
+        */
        remove.start_addr = info.dma32_window_start;
        ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
-       if (ret) {
-               RTE_LOG(ERR, EAL, "  cannot remove default DMA window, "
-                               "error %i (%s)\n", errno, strerror(errno));
+       if (ret)
                return -1;
-       }
 
-       /* create new DMA window */
-       ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_CREATE, create);
-       if (ret) {
+       /* create a new DMA window (start address is not selectable) */
+       create.window_size = spapr_dma_win_len;
+       create.page_shift  = __builtin_ctzll(spapr_dma_win_page_sz);
+       create.levels = 1;
+       ret = ioctl(vfio_container_fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
 #ifdef VFIO_IOMMU_SPAPR_INFO_DDW
-               /* try possible page_shift and levels for workaround */
+       /*
+        * The vfio_iommu_spapr_tce_info structure was modified in
+        * Linux kernel 4.2.0 to add support for the
+        * vfio_iommu_spapr_tce_ddw_info structure needed to try
+        * multiple table levels.  Skip the attempt if running with
+        * an older kernel.
+        */
+       if (ret) {
+               /* if at first we don't succeed, try more levels */
                uint32_t levels;
 
-               for (levels = create->levels + 1;
+               for (levels = create.levels + 1;
                        ret && levels <= info.ddw.levels; levels++) {
-                       create->levels = levels;
+                       create.levels = levels;
                        ret = ioctl(vfio_container_fd,
-                               VFIO_IOMMU_SPAPR_TCE_CREATE, create);
-               }
-#endif
-               if (ret) {
-                       RTE_LOG(ERR, EAL, "  cannot create new DMA window, "
-                                       "error %i (%s)\n", errno, strerror(errno));
-                       return -1;
+                               VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
                }
        }
-
-       if (create->start_addr != 0) {
-               RTE_LOG(ERR, EAL, "  DMA window start address != 0\n");
+#endif /* VFIO_IOMMU_SPAPR_INFO_DDW */
+       if (ret) {
+               RTE_LOG(ERR, EAL, "  cannot create new DMA window, error %i (%s)\n",
+                       errno, strerror(errno));
+               RTE_LOG(ERR, EAL, "  consider using a larger hugepage size "
+                       "if supported by the system\n");
                return -1;
        }
 
-       return 0;
+       /* verify the start address  */
+       if (create.start_addr != 0) {
+               RTE_LOG(ERR, EAL, "  received unsupported start address 0x%"
+                       PRIx64 "\n", (uint64_t)create.start_addr);
+               return -1;
+       }
+       return ret;
 }
 
 static int
-vfio_spapr_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
-               uint64_t len, int do_map)
+vfio_spapr_dma_mem_map(int vfio_container_fd, uint64_t vaddr,
+               uint64_t iova, uint64_t len, int do_map)
 {
-       struct spapr_walk_param param;
-       struct vfio_iommu_spapr_tce_create create = {
-               .argsz = sizeof(create),
-       };
-       struct vfio_config *vfio_cfg;
-       struct user_mem_maps *user_mem_maps;
-       int i, ret = 0;
-
-       vfio_cfg = get_vfio_cfg_by_container_fd(vfio_container_fd);
-       if (vfio_cfg == NULL) {
-               RTE_LOG(ERR, EAL, "  invalid container fd!\n");
-               return -1;
-       }
-
-       user_mem_maps = &vfio_cfg->mem_maps;
-       rte_spinlock_recursive_lock(&user_mem_maps->lock);
-
-       /* check if window size needs to be adjusted */
-       memset(&param, 0, sizeof(param));
-
-       /* we're inside a callback so use thread-unsafe version */
-       if (rte_memseg_walk_thread_unsafe(vfio_spapr_window_size_walk,
-                               &param) < 0) {
-               RTE_LOG(ERR, EAL, "Could not get window size\n");
-               ret = -1;
-               goto out;
-       }
-
-       /* also check user maps */
-       for (i = 0; i < user_mem_maps->n_maps; i++) {
-               uint64_t max = user_mem_maps->maps[i].iova +
-                               user_mem_maps->maps[i].len;
-               param.window_size = RTE_MAX(param.window_size, max);
-       }
-
-       /* sPAPR requires window size to be a power of 2 */
-       create.window_size = rte_align64pow2(param.window_size);
-       create.page_shift = __builtin_ctzll(param.hugepage_sz);
-       create.levels = 1;
+       int ret = 0;
 
        if (do_map) {
-               /* re-create window and remap the entire memory */
-               if (iova + len > create.window_size) {
-                       /* release all maps before recreating the window */
-                       if (rte_memseg_walk_thread_unsafe(vfio_spapr_unmap_walk,
-                                       &vfio_container_fd) < 0) {
-                               RTE_LOG(ERR, EAL, "Could not release DMA maps\n");
-                               ret = -1;
-                               goto out;
-                       }
-                       /* release all user maps */
-                       for (i = 0; i < user_mem_maps->n_maps; i++) {
-                               struct user_mem_map *map =
-                                               &user_mem_maps->maps[i];
-                               if (vfio_spapr_dma_do_map(vfio_container_fd,
-                                               map->addr, map->iova, map->len,
-                                               0)) {
-                                       RTE_LOG(ERR, EAL, "Could not release user DMA maps\n");
-                                       ret = -1;
-                                       goto out;
-                               }
-                       }
-                       create.window_size = rte_align64pow2(iova + len);
-                       if (vfio_spapr_create_new_dma_window(vfio_container_fd,
-                                       &create) < 0) {
-                               RTE_LOG(ERR, EAL, "Could not create new DMA window\n");
-                               ret = -1;
-                               goto out;
-                       }
-                       /* we're inside a callback, so use thread-unsafe version
-                        */
-                       if (rte_memseg_walk_thread_unsafe(vfio_spapr_map_walk,
-                                       &vfio_container_fd) < 0) {
-                               RTE_LOG(ERR, EAL, "Could not recreate DMA maps\n");
-                               ret = -1;
-                               goto out;
-                       }
-                       /* remap all user maps */
-                       for (i = 0; i < user_mem_maps->n_maps; i++) {
-                               struct user_mem_map *map =
-                                               &user_mem_maps->maps[i];
-                               if (vfio_spapr_dma_do_map(vfio_container_fd,
-                                               map->addr, map->iova, map->len,
-                                               1)) {
-                                       RTE_LOG(ERR, EAL, "Could not recreate user DMA maps\n");
-                                       ret = -1;
-                                       goto out;
-                               }
-                       }
-               }
-               if (vfio_spapr_dma_do_map(vfio_container_fd, vaddr, iova, len, 1)) {
+               if (vfio_spapr_dma_do_map(vfio_container_fd,
+                       vaddr, iova, len, 1)) {
                        RTE_LOG(ERR, EAL, "Failed to map DMA\n");
                        ret = -1;
-                       goto out;
                }
        } else {
-               /* for unmap, check if iova within DMA window */
-               if (iova > create.window_size) {
-                       RTE_LOG(ERR, EAL, "iova beyond DMA window for unmap");
+               if (vfio_spapr_dma_do_map(vfio_container_fd,
+                       vaddr, iova, len, 0)) {
+                       RTE_LOG(ERR, EAL, "Failed to unmap DMA\n");
                        ret = -1;
-                       goto out;
                }
-
-               vfio_spapr_dma_do_map(vfio_container_fd, vaddr, iova, len, 0);
        }
-out:
-       rte_spinlock_recursive_unlock(&user_mem_maps->lock);
+
        return ret;
 }
 
 static int
 vfio_spapr_dma_map(int vfio_container_fd)
 {
-       struct vfio_iommu_spapr_tce_create create = {
-               .argsz = sizeof(create),
-       };
-       struct spapr_walk_param param;
-
-       memset(&param, 0, sizeof(param));
-
-       /* create DMA window from 0 to max(phys_addr + len) */
-       rte_memseg_walk(vfio_spapr_window_size_walk, &param);
-
-       /* sPAPR requires window size to be a power of 2 */
-       create.window_size = rte_align64pow2(param.window_size);
-       create.page_shift = __builtin_ctzll(param.hugepage_sz);
-       create.levels = 1;
-
-       if (vfio_spapr_create_new_dma_window(vfio_container_fd, &create) < 0) {
-               RTE_LOG(ERR, EAL, "Could not create new DMA window\n");
+       if (vfio_spapr_create_dma_window(vfio_container_fd) < 0) {
+               RTE_LOG(ERR, EAL, "Could not create new DMA window!\n");
                return -1;
        }
 
-       /* map all DPDK segments for DMA. use 1:1 PA to IOVA mapping */
+       /* map all existing DPDK segments for DMA */
        if (rte_memseg_walk(vfio_spapr_map_walk, &vfio_container_fd) < 0)
                return -1;