net/mlx5: check VLAN push/pop support
[dpdk.git] / drivers / common / mlx5 / mlx5_common.c
index 9c88a63..459cf4b 100644 (file)
  * Copyright 2019 Mellanox Technologies, Ltd
  */
 
-#include <dlfcn.h>
 #include <unistd.h>
 #include <string.h>
+#include <stdio.h>
 
 #include <rte_errno.h>
+#include <rte_mempool.h>
+#include <rte_class.h>
+#include <rte_malloc.h>
 
 #include "mlx5_common.h"
-#include "mlx5_common_utils.h"
-#include "mlx5_glue.h"
+#include "mlx5_common_os.h"
+#include "mlx5_common_log.h"
+#include "mlx5_common_private.h"
 
+uint8_t haswell_broadwell_cpu;
 
-int mlx5_common_logtype;
-
-
-#ifdef RTE_IBVERBS_LINK_DLOPEN
-
+/* In case this is an x86_64 intel processor to check if
+ * we should use relaxed ordering.
+ */
+#ifdef RTE_ARCH_X86_64
 /**
- * Suffix RTE_EAL_PMD_PATH with "-glue".
- *
- * This function performs a sanity check on RTE_EAL_PMD_PATH before
- * suffixing its last component.
+ * This function returns processor identification and feature information
+ * into the registers.
  *
- * @param buf[out]
- *   Output buffer, should be large enough otherwise NULL is returned.
- * @param size
- *   Size of @p out.
- *
- * @return
- *   Pointer to @p buf or @p NULL in case suffix cannot be appended.
+ * @param eax, ebx, ecx, edx
+ *             Pointers to the registers that will hold cpu information.
+ * @param level
+ *             The main category of information returned.
  */
-static char *
-mlx5_glue_path(char *buf, size_t size)
-{
-       static const char *const bad[] = { "/", ".", "..", NULL };
-       const char *path = RTE_EAL_PMD_PATH;
-       size_t len = strlen(path);
-       size_t off;
-       int i;
-
-       while (len && path[len - 1] == '/')
-               --len;
-       for (off = len; off && path[off - 1] != '/'; --off)
-               ;
-       for (i = 0; bad[i]; ++i)
-               if (!strncmp(path + off, bad[i], (int)(len - off)))
-                       goto error;
-       i = snprintf(buf, size, "%.*s-glue", (int)len, path);
-       if (i == -1 || (size_t)i >= size)
-               goto error;
-       return buf;
-error:
-       RTE_LOG(ERR, PMD, "unable to append \"-glue\" to last component of"
-               " RTE_EAL_PMD_PATH (\"" RTE_EAL_PMD_PATH "\"), please"
-               " re-configure DPDK");
-       return NULL;
+static inline void mlx5_cpu_id(unsigned int level,
+                               unsigned int *eax, unsigned int *ebx,
+                               unsigned int *ecx, unsigned int *edx)
+{
+       __asm__("cpuid\n\t"
+               : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+               : "0" (level));
 }
 #endif
 
-/**
- * Initialization routine for run-time dependency on rdma-core.
- */
-RTE_INIT_PRIO(mlx5_glue_init, CLASS)
+RTE_LOG_REGISTER_DEFAULT(mlx5_common_logtype, NOTICE)
+
+/* Head of list of drivers. */
+static TAILQ_HEAD(mlx5_drivers, mlx5_class_driver) drivers_list =
+                               TAILQ_HEAD_INITIALIZER(drivers_list);
+
+/* Head of devices. */
+static TAILQ_HEAD(mlx5_devices, mlx5_common_device) devices_list =
+                               TAILQ_HEAD_INITIALIZER(devices_list);
+
+static const struct {
+       const char *name;
+       unsigned int drv_class;
+} mlx5_classes[] = {
+       { .name = "vdpa", .drv_class = MLX5_CLASS_VDPA },
+       { .name = "eth", .drv_class = MLX5_CLASS_ETH },
+       /* Keep class "net" for backward compatibility. */
+       { .name = "net", .drv_class = MLX5_CLASS_ETH },
+       { .name = "regex", .drv_class = MLX5_CLASS_REGEX },
+       { .name = "compress", .drv_class = MLX5_CLASS_COMPRESS },
+       { .name = "crypto", .drv_class = MLX5_CLASS_CRYPTO },
+};
+
+static int
+class_name_to_value(const char *class_name)
 {
-       void *handle = NULL;
+       unsigned int i;
 
-       /* Initialize common log type. */
-       mlx5_common_logtype = rte_log_register("pmd.common.mlx5");
-       if (mlx5_common_logtype >= 0)
-               rte_log_set_level(mlx5_common_logtype, RTE_LOG_NOTICE);
-       /*
-        * RDMAV_HUGEPAGES_SAFE tells ibv_fork_init() we intend to use
-        * huge pages. Calling ibv_fork_init() during init allows
-        * applications to use fork() safely for purposes other than
-        * using this PMD, which is not supported in forked processes.
-        */
-       setenv("RDMAV_HUGEPAGES_SAFE", "1", 1);
-       /* Match the size of Rx completion entry to the size of a cacheline. */
-       if (RTE_CACHE_LINE_SIZE == 128)
-               setenv("MLX5_CQE_SIZE", "128", 0);
-       /*
-        * MLX5_DEVICE_FATAL_CLEANUP tells ibv_destroy functions to
-        * cleanup all the Verbs resources even when the device was removed.
-        */
-       setenv("MLX5_DEVICE_FATAL_CLEANUP", "1", 1);
-       /* The glue initialization was done earlier by mlx5 common library. */
-#ifdef RTE_IBVERBS_LINK_DLOPEN
-       char glue_path[sizeof(RTE_EAL_PMD_PATH) - 1 + sizeof("-glue")];
-       const char *path[] = {
-               /*
-                * A basic security check is necessary before trusting
-                * MLX5_GLUE_PATH, which may override RTE_EAL_PMD_PATH.
-                */
-               (geteuid() == getuid() && getegid() == getgid() ?
-                getenv("MLX5_GLUE_PATH") : NULL),
-               /*
-                * When RTE_EAL_PMD_PATH is set, use its glue-suffixed
-                * variant, otherwise let dlopen() look up libraries on its
-                * own.
+       for (i = 0; i < RTE_DIM(mlx5_classes); i++) {
+               if (strcmp(class_name, mlx5_classes[i].name) == 0)
+                       return mlx5_classes[i].drv_class;
+       }
+       return -EINVAL;
+}
+
+static struct mlx5_class_driver *
+driver_get(uint32_t class)
+{
+       struct mlx5_class_driver *driver;
+
+       TAILQ_FOREACH(driver, &drivers_list, next) {
+               if ((uint32_t)driver->drv_class == class)
+                       return driver;
+       }
+       return NULL;
+}
+
+static int
+devargs_class_handler(__rte_unused const char *key,
+                     const char *class_names, void *opaque)
+{
+       int *ret = opaque;
+       int class_val;
+       char *scratch;
+       char *found;
+       char *refstr = NULL;
+
+       *ret = 0;
+       scratch = strdup(class_names);
+       if (scratch == NULL) {
+               *ret = -ENOMEM;
+               return *ret;
+       }
+       found = strtok_r(scratch, ":", &refstr);
+       if (found == NULL)
+               /* Empty string. */
+               goto err;
+       do {
+               /* Extract each individual class name. Multiple
+                * classes can be supplied as class=net:regex:foo:bar.
                 */
-               (*RTE_EAL_PMD_PATH ?
-                mlx5_glue_path(glue_path, sizeof(glue_path)) : ""),
-       };
+               class_val = class_name_to_value(found);
+               /* Check if its a valid class. */
+               if (class_val < 0) {
+                       *ret = -EINVAL;
+                       goto err;
+               }
+               *ret |= class_val;
+               found = strtok_r(NULL, ":", &refstr);
+       } while (found != NULL);
+err:
+       free(scratch);
+       if (*ret < 0)
+               DRV_LOG(ERR, "Invalid mlx5 class options: %s.\n", class_names);
+       return *ret;
+}
+
+static int
+parse_class_options(const struct rte_devargs *devargs)
+{
+       struct rte_kvargs *kvlist;
+       int ret = 0;
+
+       if (devargs == NULL)
+               return 0;
+       if (devargs->cls != NULL && devargs->cls->name != NULL)
+               /* Global syntax, only one class type. */
+               return class_name_to_value(devargs->cls->name);
+       /* Legacy devargs support multiple classes. */
+       kvlist = rte_kvargs_parse(devargs->args, NULL);
+       if (kvlist == NULL)
+               return 0;
+       rte_kvargs_process(kvlist, RTE_DEVARGS_KEY_CLASS,
+                          devargs_class_handler, &ret);
+       rte_kvargs_free(kvlist);
+       return ret;
+}
+
+static const unsigned int mlx5_class_invalid_combinations[] = {
+       MLX5_CLASS_ETH | MLX5_CLASS_VDPA,
+       /* New class combination should be added here. */
+};
+
+static int
+is_valid_class_combination(uint32_t user_classes)
+{
+       unsigned int i;
+
+       /* Verify if user specified unsupported combination. */
+       for (i = 0; i < RTE_DIM(mlx5_class_invalid_combinations); i++) {
+               if ((mlx5_class_invalid_combinations[i] & user_classes) ==
+                   mlx5_class_invalid_combinations[i])
+                       return -EINVAL;
+       }
+       /* Not found any invalid class combination. */
+       return 0;
+}
+
+static bool
+device_class_enabled(const struct mlx5_common_device *device, uint32_t class)
+{
+       return (device->classes_loaded & class) > 0;
+}
+
+static bool
+mlx5_bus_match(const struct mlx5_class_driver *drv,
+              const struct rte_device *dev)
+{
+       if (mlx5_dev_is_pci(dev))
+               return mlx5_dev_pci_match(drv, dev);
+       return true;
+}
+
+static struct mlx5_common_device *
+to_mlx5_device(const struct rte_device *rte_dev)
+{
+       struct mlx5_common_device *dev;
+
+       TAILQ_FOREACH(dev, &devices_list, next) {
+               if (rte_dev == dev->dev)
+                       return dev;
+       }
+       return NULL;
+}
+
+int
+mlx5_dev_to_pci_str(const struct rte_device *dev, char *addr, size_t size)
+{
+       struct rte_pci_addr pci_addr = { 0 };
+       int ret;
+
+       if (mlx5_dev_is_pci(dev)) {
+               /* Input might be <BDF>, format PCI address to <DBDF>. */
+               ret = rte_pci_addr_parse(dev->name, &pci_addr);
+               if (ret != 0)
+                       return -ENODEV;
+               rte_pci_device_name(&pci_addr, addr, size);
+               return 0;
+       }
+#ifdef RTE_EXEC_ENV_LINUX
+       return mlx5_auxiliary_get_pci_str(RTE_DEV_TO_AUXILIARY_CONST(dev),
+                       addr, size);
+#else
+       rte_errno = ENODEV;
+       return -rte_errno;
+#endif
+}
+
+static void
+dev_release(struct mlx5_common_device *dev)
+{
+       TAILQ_REMOVE(&devices_list, dev, next);
+       rte_free(dev);
+}
+
+static int
+drivers_remove(struct mlx5_common_device *dev, uint32_t enabled_classes)
+{
+       struct mlx5_class_driver *driver;
+       int local_ret = -ENODEV;
        unsigned int i = 0;
-       void **sym;
-       const char *dlmsg;
+       int ret = 0;
 
-       while (!handle && i != RTE_DIM(path)) {
-               const char *end;
-               size_t len;
-               int ret;
+       enabled_classes &= dev->classes_loaded;
+       while (enabled_classes) {
+               driver = driver_get(RTE_BIT64(i));
+               if (driver != NULL) {
+                       local_ret = driver->remove(dev->dev);
+                       if (local_ret == 0)
+                               dev->classes_loaded &= ~RTE_BIT64(i);
+                       else if (ret == 0)
+                               ret = local_ret;
+               }
+               enabled_classes &= ~RTE_BIT64(i);
+               i++;
+       }
+       if (local_ret != 0 && ret == 0)
+               ret = local_ret;
+       return ret;
+}
+
+static int
+drivers_probe(struct mlx5_common_device *dev, uint32_t user_classes)
+{
+       struct mlx5_class_driver *driver;
+       uint32_t enabled_classes = 0;
+       bool already_loaded;
+       int ret;
 
-               if (!path[i]) {
-                       ++i;
+       TAILQ_FOREACH(driver, &drivers_list, next) {
+               if ((driver->drv_class & user_classes) == 0)
                        continue;
+               if (!mlx5_bus_match(driver, dev->dev))
+                       continue;
+               already_loaded = dev->classes_loaded & driver->drv_class;
+               if (already_loaded && driver->probe_again == 0) {
+                       DRV_LOG(ERR, "Device %s is already probed",
+                               dev->dev->name);
+                       ret = -EEXIST;
+                       goto probe_err;
+               }
+               ret = driver->probe(dev->dev);
+               if (ret < 0) {
+                       DRV_LOG(ERR, "Failed to load driver %s",
+                               driver->name);
+                       goto probe_err;
+               }
+               enabled_classes |= driver->drv_class;
+       }
+       dev->classes_loaded |= enabled_classes;
+       return 0;
+probe_err:
+       /* Only unload drivers which are enabled which were enabled
+        * in this probe instance.
+        */
+       drivers_remove(dev, enabled_classes);
+       return ret;
+}
+
+int
+mlx5_common_dev_probe(struct rte_device *eal_dev)
+{
+       struct mlx5_common_device *dev;
+       uint32_t classes = 0;
+       bool new_device = false;
+       int ret;
+
+       DRV_LOG(INFO, "probe device \"%s\".", eal_dev->name);
+       ret = parse_class_options(eal_dev->devargs);
+       if (ret < 0) {
+               DRV_LOG(ERR, "Unsupported mlx5 class type: %s",
+                       eal_dev->devargs->args);
+               return ret;
+       }
+       classes = ret;
+       if (classes == 0)
+               /* Default to net class. */
+               classes = MLX5_CLASS_ETH;
+       dev = to_mlx5_device(eal_dev);
+       if (!dev) {
+               dev = rte_zmalloc("mlx5_common_device", sizeof(*dev), 0);
+               if (!dev)
+                       return -ENOMEM;
+               dev->dev = eal_dev;
+               TAILQ_INSERT_HEAD(&devices_list, dev, next);
+               new_device = true;
+       } else {
+               /* Validate combination here. */
+               ret = is_valid_class_combination(classes |
+                                                dev->classes_loaded);
+               if (ret != 0) {
+                       DRV_LOG(ERR, "Unsupported mlx5 classes combination.");
+                       return ret;
                }
-               end = strpbrk(path[i], ":;");
-               if (!end)
-                       end = path[i] + strlen(path[i]);
-               len = end - path[i];
-               ret = 0;
-               do {
-                       char name[ret + 1];
-
-                       ret = snprintf(name, sizeof(name), "%.*s%s" MLX5_GLUE,
-                                      (int)len, path[i],
-                                      (!len || *(end - 1) == '/') ? "" : "/");
-                       if (ret == -1)
-                               break;
-                       if (sizeof(name) != (size_t)ret + 1)
-                               continue;
-                       DRV_LOG(DEBUG, "Looking for rdma-core glue as "
-                               "\"%s\"", name);
-                       handle = dlopen(name, RTLD_LAZY);
+       }
+       ret = drivers_probe(dev, classes);
+       if (ret)
+               goto class_err;
+       return 0;
+class_err:
+       if (new_device)
+               dev_release(dev);
+       return ret;
+}
+
+int
+mlx5_common_dev_remove(struct rte_device *eal_dev)
+{
+       struct mlx5_common_device *dev;
+       int ret;
+
+       dev = to_mlx5_device(eal_dev);
+       if (!dev)
+               return -ENODEV;
+       /* Matching device found, cleanup and unload drivers. */
+       ret = drivers_remove(dev, dev->classes_loaded);
+       if (ret != 0)
+               dev_release(dev);
+       return ret;
+}
+
+int
+mlx5_common_dev_dma_map(struct rte_device *dev, void *addr, uint64_t iova,
+                       size_t len)
+{
+       struct mlx5_class_driver *driver = NULL;
+       struct mlx5_class_driver *temp;
+       struct mlx5_common_device *mdev;
+       int ret = -EINVAL;
+
+       mdev = to_mlx5_device(dev);
+       if (!mdev)
+               return -ENODEV;
+       TAILQ_FOREACH(driver, &drivers_list, next) {
+               if (!device_class_enabled(mdev, driver->drv_class) ||
+                   driver->dma_map == NULL)
+                       continue;
+               ret = driver->dma_map(dev, addr, iova, len);
+               if (ret)
+                       goto map_err;
+       }
+       return ret;
+map_err:
+       TAILQ_FOREACH(temp, &drivers_list, next) {
+               if (temp == driver)
                        break;
-               } while (1);
-               path[i] = end + 1;
-               if (!*end)
-                       ++i;
-       }
-       if (!handle) {
-               rte_errno = EINVAL;
-               dlmsg = dlerror();
-               if (dlmsg)
-                       DRV_LOG(WARNING, "Cannot load glue library: %s", dlmsg);
-               goto glue_error;
-       }
-       sym = dlsym(handle, "mlx5_glue");
-       if (!sym || !*sym) {
-               rte_errno = EINVAL;
-               dlmsg = dlerror();
-               if (dlmsg)
-                       DRV_LOG(ERR, "Cannot resolve glue symbol: %s", dlmsg);
-               goto glue_error;
-       }
-       mlx5_glue = *sym;
-#endif /* RTE_IBVERBS_LINK_DLOPEN */
-#ifndef NDEBUG
-       /* Glue structure must not contain any NULL pointers. */
-       {
-               unsigned int i;
-
-               for (i = 0; i != sizeof(*mlx5_glue) / sizeof(void *); ++i)
-                       assert(((const void *const *)mlx5_glue)[i]);
+               if (device_class_enabled(mdev, temp->drv_class) &&
+                   temp->dma_map && temp->dma_unmap)
+                       temp->dma_unmap(dev, addr, iova, len);
        }
+       return ret;
+}
+
+int
+mlx5_common_dev_dma_unmap(struct rte_device *dev, void *addr, uint64_t iova,
+                         size_t len)
+{
+       struct mlx5_class_driver *driver;
+       struct mlx5_common_device *mdev;
+       int local_ret = -EINVAL;
+       int ret = 0;
+
+       mdev = to_mlx5_device(dev);
+       if (!mdev)
+               return -ENODEV;
+       /* There is no unmap error recovery in current implementation. */
+       TAILQ_FOREACH_REVERSE(driver, &drivers_list, mlx5_drivers, next) {
+               if (!device_class_enabled(mdev, driver->drv_class) ||
+                   driver->dma_unmap == NULL)
+                       continue;
+               local_ret = driver->dma_unmap(dev, addr, iova, len);
+               if (local_ret && (ret == 0))
+                       ret = local_ret;
+       }
+       if (local_ret)
+               ret = local_ret;
+       return ret;
+}
+
+void
+mlx5_class_driver_register(struct mlx5_class_driver *driver)
+{
+       mlx5_common_driver_on_register_pci(driver);
+       TAILQ_INSERT_TAIL(&drivers_list, driver, next);
+}
+
+static void mlx5_common_driver_init(void)
+{
+       mlx5_common_pci_init();
+#ifdef RTE_EXEC_ENV_LINUX
+       mlx5_common_auxiliary_init();
 #endif
-       if (strcmp(mlx5_glue->version, MLX5_GLUE_VERSION)) {
-               rte_errno = EINVAL;
-               DRV_LOG(ERR, "rdma-core glue \"%s\" mismatch: \"%s\" is "
-                       "required", mlx5_glue->version, MLX5_GLUE_VERSION);
-               goto glue_error;
-       }
-       mlx5_glue->fork_init();
-       return;
-glue_error:
-       if (handle)
-               dlclose(handle);
-       DRV_LOG(WARNING, "Cannot initialize MLX5 common due to missing"
-               " run-time dependency on rdma-core libraries (libibverbs,"
-               " libmlx5)");
-       mlx5_glue = NULL;
-       return;
 }
+
+static bool mlx5_common_initialized;
+
+/**
+ * One time innitialization routine for run-time dependency on glue library
+ * for multiple PMDs. Each mlx5 PMD that depends on mlx5_common module,
+ * must invoke in its constructor.
+ */
+void
+mlx5_common_init(void)
+{
+       if (mlx5_common_initialized)
+               return;
+
+       mlx5_glue_constructor();
+       mlx5_common_driver_init();
+       mlx5_common_initialized = true;
+}
+
+/**
+ * This function is responsible of initializing the variable
+ *  haswell_broadwell_cpu by checking if the cpu is intel
+ *  and reading the data returned from mlx5_cpu_id().
+ *  since haswell and broadwell cpus don't have improved performance
+ *  when using relaxed ordering we want to check the cpu type before
+ *  before deciding whether to enable RO or not.
+ *  if the cpu is haswell or broadwell the variable will be set to 1
+ *  otherwise it will be 0.
+ */
+RTE_INIT_PRIO(mlx5_is_haswell_broadwell_cpu, LOG)
+{
+#ifdef RTE_ARCH_X86_64
+       unsigned int broadwell_models[4] = {0x3d, 0x47, 0x4F, 0x56};
+       unsigned int haswell_models[4] = {0x3c, 0x3f, 0x45, 0x46};
+       unsigned int i, model, family, brand_id, vendor;
+       unsigned int signature_intel_ebx = 0x756e6547;
+       unsigned int extended_model;
+       unsigned int eax = 0;
+       unsigned int ebx = 0;
+       unsigned int ecx = 0;
+       unsigned int edx = 0;
+       int max_level;
+
+       mlx5_cpu_id(0, &eax, &ebx, &ecx, &edx);
+       vendor = ebx;
+       max_level = eax;
+       if (max_level < 1) {
+               haswell_broadwell_cpu = 0;
+               return;
+       }
+       mlx5_cpu_id(1, &eax, &ebx, &ecx, &edx);
+       model = (eax >> 4) & 0x0f;
+       family = (eax >> 8) & 0x0f;
+       brand_id = ebx & 0xff;
+       extended_model = (eax >> 12) & 0xf0;
+       /* Check if the processor is Haswell or Broadwell */
+       if (vendor == signature_intel_ebx) {
+               if (family == 0x06)
+                       model += extended_model;
+               if (brand_id == 0 && family == 0x6) {
+                       for (i = 0; i < RTE_DIM(broadwell_models); i++)
+                               if (model == broadwell_models[i]) {
+                                       haswell_broadwell_cpu = 1;
+                                       return;
+                               }
+                       for (i = 0; i < RTE_DIM(haswell_models); i++)
+                               if (model == haswell_models[i]) {
+                                       haswell_broadwell_cpu = 1;
+                                       return;
+                               }
+               }
+       }
+#endif
+       haswell_broadwell_cpu = 0;
+}
+
+/**
+ * Allocate the User Access Region with DevX on specified device.
+ *
+ * @param [in] ctx
+ *   Infiniband device context to perform allocation on.
+ * @param [in] mapping
+ *   MLX5DV_UAR_ALLOC_TYPE_BF - allocate as cached memory with write-combining
+ *                             attributes (if supported by the host), the
+ *                             writes to the UAR registers must be followed
+ *                             by write memory barrier.
+ *   MLX5DV_UAR_ALLOC_TYPE_NC - allocate as non-cached nenory, all writes are
+ *                             promoted to the registers immediately, no
+ *                             memory barriers needed.
+ *   mapping < 0 - the first attempt is performed with MLX5DV_UAR_ALLOC_TYPE_BF,
+ *                if this fails the next attempt with MLX5DV_UAR_ALLOC_TYPE_NC
+ *                is performed. The drivers specifying negative values should
+ *                always provide the write memory barrier operation after UAR
+ *                register writings.
+ * If there is no definitions for the MLX5DV_UAR_ALLOC_TYPE_xx (older rdma
+ * library headers), the caller can specify 0.
+ *
+ * @return
+ *   UAR object pointer on success, NULL otherwise and rte_errno is set.
+ */
+void *
+mlx5_devx_alloc_uar(void *ctx, int mapping)
+{
+       void *uar;
+       uint32_t retry, uar_mapping;
+       void *base_addr;
+
+       for (retry = 0; retry < MLX5_ALLOC_UAR_RETRY; ++retry) {
+#ifdef MLX5DV_UAR_ALLOC_TYPE_NC
+               /* Control the mapping type according to the settings. */
+               uar_mapping = (mapping < 0) ?
+                             MLX5DV_UAR_ALLOC_TYPE_NC : mapping;
+#else
+               /*
+                * It seems we have no way to control the memory mapping type
+                * for the UAR, the default "Write-Combining" type is supposed.
+                */
+               uar_mapping = 0;
+               RTE_SET_USED(mapping);
+#endif
+               uar = mlx5_glue->devx_alloc_uar(ctx, uar_mapping);
+#ifdef MLX5DV_UAR_ALLOC_TYPE_NC
+               if (!uar &&
+                   mapping < 0 &&
+                   uar_mapping == MLX5DV_UAR_ALLOC_TYPE_BF) {
+                       /*
+                        * In some environments like virtual machine the
+                        * Write Combining mapped might be not supported and
+                        * UAR allocation fails. We tried "Non-Cached" mapping
+                        * for the case.
+                        */
+                       DRV_LOG(WARNING, "Failed to allocate DevX UAR (BF)");
+                       uar_mapping = MLX5DV_UAR_ALLOC_TYPE_NC;
+                       uar = mlx5_glue->devx_alloc_uar(ctx, uar_mapping);
+               } else if (!uar &&
+                          mapping < 0 &&
+                          uar_mapping == MLX5DV_UAR_ALLOC_TYPE_NC) {
+                       /*
+                        * If Verbs/kernel does not support "Non-Cached"
+                        * try the "Write-Combining".
+                        */
+                       DRV_LOG(WARNING, "Failed to allocate DevX UAR (NC)");
+                       uar_mapping = MLX5DV_UAR_ALLOC_TYPE_BF;
+                       uar = mlx5_glue->devx_alloc_uar(ctx, uar_mapping);
+               }
+#endif
+               if (!uar) {
+                       DRV_LOG(ERR, "Failed to allocate DevX UAR (BF/NC)");
+                       rte_errno = ENOMEM;
+                       goto exit;
+               }
+               base_addr = mlx5_os_get_devx_uar_base_addr(uar);
+               if (base_addr)
+                       break;
+               /*
+                * The UARs are allocated by rdma_core within the
+                * IB device context, on context closure all UARs
+                * will be freed, should be no memory/object leakage.
+                */
+               DRV_LOG(WARNING, "Retrying to allocate DevX UAR");
+               uar = NULL;
+       }
+       /* Check whether we finally succeeded with valid UAR allocation. */
+       if (!uar) {
+               DRV_LOG(ERR, "Failed to allocate DevX UAR (NULL base)");
+               rte_errno = ENOMEM;
+       }
+       /*
+        * Return void * instead of struct mlx5dv_devx_uar *
+        * is for compatibility with older rdma-core library headers.
+        */
+exit:
+       return uar;
+}
+
+RTE_PMD_EXPORT_NAME(mlx5_common_driver, __COUNTER__);