vfio: revert retry logic for MSI-X BAR mapping

This reverts commit d4774a568ba0a5923229974a002972c83eb04570.

The patch is incomplete because kernel 4.16+, while being capable
of mapping MSI-X BARs, will also report if such a capability is
available. Without checking this capability, gratuitous errors
are displayed on kernels <4.16 while VFIO is attempting to mmap
MSI-X BAR and fails, which can be confusing to the user.

Fixes: d4774a568ba0 ("vfio: fix workaround of BAR mapping")

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index bb6ef7b..686386d 100644 (file)
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -332,59 +332,50 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res,
        void *bar_addr;
        struct pci_msix_table *msix_table = &vfio_res->msix_table;
        struct pci_map *bar = &vfio_res->maps[bar_index];
-       bool again = false;
 
        if (bar->size == 0)
                /* Skip this BAR */
                return 0;
 
+       if (msix_table->bar_index == bar_index) {
+               /*
+                * VFIO will not let us map the MSI-X table,
+                * but we can map around it.
+                */
+               uint32_t table_start = msix_table->offset;
+               uint32_t table_end = table_start + msix_table->size;
+               table_end = (table_end + ~PAGE_MASK) & PAGE_MASK;
+               table_start &= PAGE_MASK;
+
+               if (table_start == 0 && table_end >= bar->size) {
+                       /* Cannot map this BAR */
+                       RTE_LOG(DEBUG, EAL, "Skipping BAR%d\n", bar_index);
+                       bar->size = 0;
+                       bar->addr = 0;
+                       return 0;
+               }
+
+               memreg[0].offset = bar->offset;
+               memreg[0].size = table_start;
+               memreg[1].offset = bar->offset + table_end;
+               memreg[1].size = bar->size - table_end;
+
+               RTE_LOG(DEBUG, EAL,
+                       "Trying to map BAR%d that contains the MSI-X "
+                       "table. Trying offsets: "
+                       "0x%04lx:0x%04lx, 0x%04lx:0x%04lx\n", bar_index,
+                       memreg[0].offset, memreg[0].size,
+                       memreg[1].offset, memreg[1].size);
+       } else {
+               memreg[0].offset = bar->offset;
+               memreg[0].size = bar->size;
+       }
+
        /* reserve the address using an inaccessible mapping */
        bar_addr = mmap(bar->addr, bar->size, 0, MAP_PRIVATE |
                        MAP_ANONYMOUS | additional_flags, -1, 0);
-       if (bar_addr == MAP_FAILED) {
-               RTE_LOG(ERR, EAL,
-                       "Failed to create inaccessible mapping for BAR%d\n",
-                       bar_index);
-               return -1;
-       }
-
-       memreg[0].offset = bar->offset;
-       memreg[0].size = bar->size;
-       do {
+       if (bar_addr != MAP_FAILED) {
                void *map_addr = NULL;
-               if (again) {
-                       /*
-                        * VFIO did not let us map the MSI-X table,
-                        * but we can map around it.
-                        */
-                       uint32_t table_start = msix_table->offset;
-                       uint32_t table_end = table_start + msix_table->size;
-                       table_end = (table_end + ~PAGE_MASK) & PAGE_MASK;
-                       table_start &= PAGE_MASK;
-
-                       if (table_start == 0 && table_end >= bar->size) {
-                               /* Cannot map this BAR */
-                               RTE_LOG(DEBUG, EAL, "Skipping BAR%d\n",
-                                               bar_index);
-                               munmap(bar_addr, bar->size);
-                               bar->size = 0;
-                               bar->addr = 0;
-                               return 0;
-                       }
-
-                       memreg[0].offset = bar->offset;
-                       memreg[0].size = table_start;
-                       memreg[1].offset = bar->offset + table_end;
-                       memreg[1].size = bar->size - table_end;
-
-                       RTE_LOG(DEBUG, EAL,
-                               "Trying to map BAR%d that contains the MSI-X "
-                               "table. Trying offsets: "
-                               "0x%04lx:0x%04lx, 0x%04lx:0x%04lx\n", bar_index,
-                               memreg[0].offset, memreg[0].size,
-                               memreg[1].offset, memreg[1].size);
-               }
-
                if (memreg[0].size) {
                        /* actual map of first part */
                        map_addr = pci_map_resource(bar_addr, vfio_dev_fd,
@@ -393,12 +384,6 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res,
                                                        MAP_FIXED);
                }
 
-               if (map_addr == MAP_FAILED &&
-                       msix_table->bar_index == bar_index && !again) {
-                       again = true;
-                       continue;
-               }
-
                /* if there's a second part, try to map it */
                if (map_addr != MAP_FAILED
                        && memreg[1].offset && memreg[1].size) {
@@ -419,8 +404,12 @@ pci_vfio_mmap_bar(int vfio_dev_fd, struct mapped_pci_resource *vfio_res,
                                        bar_index);
                        return -1;
                }
-               break;
-       } while (again);
+       } else {
+               RTE_LOG(ERR, EAL,
+                               "Failed to create inaccessible mapping for BAR%d\n",
+                               bar_index);
+               return -1;
+       }
 
        bar->addr = bar_addr;
        return 0;