From 456bb6cb658b9d332fa0b5b91946916b48ed449e Mon Sep 17 00:00:00 2001

From: Igor Mammedov <imammedo@redhat.com>

Date: Thu, 29 Jul 2021 07:42:10 -0400

Subject: [PATCH 09/39] acpi: pc: revert back to v5.2 PCI slot enumeration

RH-Author: Miroslav Rezanina <mrezanin@redhat.com>

RH-MergeRequest: 32: Synchronize with RHEL-AV 8.5 release 27 to RHEL 9

RH-Commit: [1/15] 57222343ccae17b99b4e166798d4d0eecca2e22b (mrezanin/centos-src-qemu-kvm)

RH-Bugzilla: 1957194

RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Igor Mammedov <imammedo@redhat.com>

RH-Acked-by: Andrew Jones <drjones@redhat.com>

Commit [1] moved _SUN variable from only hot-pluggable to

all devices. This made linux kernel enumerate extra slots

that weren't present before. If extra slot happens to be

be enumerated first and there is a device in th same slot

but on other bridge, linux kernel will add -N suffix to

slot name of the later, thus changing NIC name compared to

QEMU 5.2. This in some case confuses systemd, if it is

using SLOT NIC naming scheme and interface name becomes

not the same as it was under QEMU-5.2.

Reproducer QEMU CLI:

  -M pc-i440fx-5.2 -nodefaults \

  -device pci-bridge,chassis_nr=1,id=pci.1,bus=pci.0,addr=0x3 \

  -device virtio-net-pci,id=nic1,bus=pci.1,addr=0x1 \

  -device virtio-net-pci,id=nic2,bus=pci.1,addr=0x2 \

  -device virtio-net-pci,id=nic3,bus=pci.1,addr=0x3

with RHEL8 guest produces following results:

  v5.2:

     kernel: virtio_net virtio0 ens1: renamed from eth0

     kernel: virtio_net virtio2 ens3: renamed from eth2

     kernel: virtio_net virtio1 enp1s2: renamed from eth1

      (slot 2 is assigned to empty bus 0 slot and virtio1

       is assigned to 2-2 slot, and renaming falls back,

       for some reason, to path based naming scheme)

  v6.0:

     kernel: virtio_net virtio0 ens1: renamed from eth0

     kernel: virtio_net virtio2 ens3: renamed from eth2

     systemd-udevd[299]: Error changing net interface name 'eth1' to 'ens3': File exists

     systemd-udevd[299]: could not rename interface '3' from 'eth1' to 'ens3': File exists

      (with commit [1] kernel assigns virtio2 to 3-2 slot

       since bridge advertises _SUN=0x3 and kernel assigns

       slot 3 to bridge. Still it manages to rename virtio2

       correctly to ens3, however systemd gets confused with virtio1

       where slot allocation exactly the same (2-2) as in 5.2 case

       and tries to rename it to ens3 which is rightfully taken by

       virtio2)

I'm not sure what breaks in systemd interface renaming (it probably

should be investigated), but on QEMU side we can safely revert

_SUN to 5.2 behavior (i.e. avoid cold-plugged bridges and non

hot-pluggable device classes), without breaking acpi-index, which uses

slot numbers but it doesn't have to use _SUN, it could use an arbitrary

variable name that has the same slot value).

It will help existing VMs to keep networking with non trivial

configs in working order since systemd will do its interface

renaming magic as it used to do.

1)

Fixes: b7f23f62e40 (pci: acpi: add _DSM method to PCI devices)

Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Message-Id: <20210624204229.998824-3-imammedo@redhat.com>

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Tested-by: John Sucaet <john.sucaet@ekinops.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit 7193d7cdd93e50f0e5f09803b98d27d3f9b147ac)

Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/i386/acpi-build.c | 9 +++++++--

 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c

index de98750aef..dbee0cd3bc 100644

--- a/hw/i386/acpi-build.c

+++ b/hw/i386/acpi-build.c

@@ -432,11 +432,15 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,

         aml_append(dev, aml_name_decl("_ADR", aml_int(slot << 16)));

         if (bsel) {

-            aml_append(dev, aml_name_decl("_SUN", aml_int(slot)));

+            /*

+             * Can't declare _SUN here for every device as it changes 'slot'

+             * enumeration order in linux kernel, so use another variable for it

+             */

+            aml_append(dev, aml_name_decl("ASUN", aml_int(slot)));

             method = aml_method("_DSM", 4, AML_SERIALIZED);

             aml_append(method, aml_return(

                 aml_call6("PDSM", aml_arg(0), aml_arg(1), aml_arg(2),

-                          aml_arg(3), aml_name("BSEL"), aml_name("_SUN"))

+                          aml_arg(3), aml_name("BSEL"), aml_name("ASUN"))

             ));

             aml_append(dev, method);

         }

@@ -463,6 +467,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,

             aml_append(method, aml_return(aml_int(s3d)));

             aml_append(dev, method);

         } else if (hotplug_enabled_dev) {

+            aml_append(dev, aml_name_decl("_SUN", aml_int(slot)));

             /* add _EJ0 to make slot hotpluggable  */

             method = aml_method("_EJ0", 1, AML_NOTSERIALIZED);

             aml_append(method,

-- 

2.27.0