On 11/24/23 2:09 AM, christian.ehrha...@canonical.com wrote:
From: David Wilder <dwil...@us.ibm.com>

When using --no-huge option physical address are not guaranteed
to be persistent.

This change effectively makes "--no-huge" the same as
"--no-huge --iova-mode=va".

When --no-huge is used (or any other condition making physical
addresses unavailable) setting --iova-mode=pa will have no effect.

Signed-off-by: Christian Ehrhardt <christian.ehrha...@canonical.com>
---
  doc/guides/prog_guide/env_abstraction_layer.rst |  9 ++++++---
  lib/eal/linux/eal.c                             | 16 ++++++++++------
  2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst 
b/doc/guides/prog_guide/env_abstraction_layer.rst
index 6debf54efb..20c7355e0f 100644
--- a/doc/guides/prog_guide/env_abstraction_layer.rst
+++ b/doc/guides/prog_guide/env_abstraction_layer.rst
@@ -559,9 +559,12 @@ IOVA Mode is selected by considering what the current 
usable Devices on the
  system require and/or support.

  On FreeBSD, RTE_IOVA_PA is always the default. On Linux, the IOVA mode is
-detected based on a 2-step heuristic detailed below.
+detected based on a heuristic detailed below.

-For the first step, EAL asks each bus its requirement in terms of IOVA mode
+For the first step, if no Physical Addresses are available RTE_IOVA_VA is
+selected.
+
+Then EAL asks each bus its requirement in terms of IOVA mode
  and decides on a preferred IOVA mode.

  - if all buses report RTE_IOVA_PA, then the preferred IOVA mode is 
RTE_IOVA_PA,
@@ -575,7 +578,7 @@ and decides on a preferred IOVA mode.
  If the buses have expressed no preference on which IOVA mode to pick, then a
  default is selected using the following logic:

-- if physical addresses are not available, RTE_IOVA_VA mode is used
+- if enable_iova_as_pa was not set at build RTE_IOVA_VA mode is used
  - if /sys/kernel/iommu_groups is not empty, RTE_IOVA_VA mode is used
  - otherwise, RTE_IOVA_PA mode is used

diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
index 57da058cec..2f1fce3c54 100644
--- a/lib/eal/linux/eal.c
+++ b/lib/eal/linux/eal.c
@@ -1067,6 +1067,16 @@ rte_eal_init(int argc, char **argv)

        phys_addrs = rte_eal_using_phys_addrs() != 0;

+       if (!phys_addrs) {
+               /* if we have no access to physical addresses, pick IOVA as VA 
mode. */
+               if (internal_conf->iova_mode == RTE_IOVA_PA)
+                       RTE_LOG(WARNING, EAL, "WARNING: --iova-mode=pa, but Physical 
addresses are unavailable, selecting IOVA as VA mode.\n");
+               else
+                       RTE_LOG(DEBUG, EAL, "Physical addresses are unavailable, 
selecting IOVA as VA mode.\n");
+               internal_conf->iova_mode = RTE_IOVA_VA;
+               rte_eal_get_configuration()->iova_mode = 
internal_conf->iova_mode;
+       }
+
        /* if no EAL option "--iova-mode=<pa|va>", use bus IOVA scheme */
        if (internal_conf->iova_mode == RTE_IOVA_DC) {
                /* autodetect the IOVA mapping mode */
@@ -1078,12 +1088,6 @@ rte_eal_init(int argc, char **argv)
                        if (!RTE_IOVA_IN_MBUF) {
                                iova_mode = RTE_IOVA_VA;
                                RTE_LOG(DEBUG, EAL, "IOVA as VA mode is forced by 
build option.\n");
-                       } else if (!phys_addrs) {
-                               /* if we have no access to physical addresses,
-                                * pick IOVA as VA mode.
-                                */
-                               iova_mode = RTE_IOVA_VA;
-                               RTE_LOG(DEBUG, EAL, "Physical addresses are 
unavailable, selecting IOVA as VA mode.\n");
                        } else if (is_iommu_enabled()) {
                                /* we have an IOMMU, pick IOVA as VA mode */
                                iova_mode = RTE_IOVA_VA;

What tests are you running that generate an error without explicitly selecting the iova-mode? When I run the fast-tests I see the system correctly selecting VA without any additional command-line parameters when running 23.11:


21:47:05 DPDK_TEST=acl_autotest MALLOC_PERTURB_=201 /home/drc/src/dpdk/build/app/dpdk-test --no-huge -m 2048 ----------------------------------- output -----------------------------------
stdout:
RTE>>acl_autotest
acl context <acl_ctx>@0x179cbd300
  socket_id=-1
  alg=5
  first_load_sz=0
  max_rules=196608
  rule_size=128
  num_rules=0
  num_categories=0
  num_tries=0
acl context <acl_ctx>@0x179cbd300
  socket_id=-1
  alg=5
  first_load_sz=0
  max_rules=196608
  rule_size=128
  num_rules=0
  num_categories=0
  num_tries=0
running test_convert_rules(acl_ipv4vlan_tuple)
running test_convert_rules(acl_ipv4vlan_tuple, RTE_ACL_FIELD_TYPE_BITMASK type for IPv4) running test_convert_rules(acl_ipv4vlan_tuple, RTE_ACL_FIELD_TYPE_RANGE type for IPv4)
running test_convert_rules(acl_ipv4vlan_tuple: swap VLAN and PORTs order)
running test_convert_rules(acl_ipv4vlan_tuple: swap SRC and DST IPv4 order)
test_u32_range#1704 starting range test from 0 to 264192
Test OK
RTE>>
stderr:
EAL: Detected CPU lcores: 128
EAL: Detected NUMA nodes: 2
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'

Dave

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