* [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix
@ 2026-09-07 11:00 Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 1/4] tests: add test with q35 and scsihw2 Dominik Csapak
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 11:00 UTC (permalink / raw)
To: pve-devel
Main motivation for this series was a defect in how we handle
hotplugging certain devices:
When e.g. adding scsi15 on a vm with i440fx + lsi controller, we'd need
scsihw2 (since only 7 devices can live on scsihw0 and scsihw1
respectively) which sits on bus pci.4. This itself is not added by
default to the config, so we tried to hotplug the bridge. This works,
but without SHPC (which is neither the default, nor does it work
reliably in all guests) one cannot hot-plug anything into a hot-plugged
bridge. So when hotplugging scsi15 in this example, we'd hot-plug
pci.4, but adding scsihw2 would fail and leave the disk in 'pending'.
When now a live-migration is initiated, the already added bridge is
never recorded in the config, and the guest crashes on the remote
after it's resumed.
Since this is a rather narrow case, I'd opted for preventing
hot-plugging bridges completely.
Further I tried to refactor and cleanup the bridge adding code a bit,
so we don't have to pass the 'bridges' hash around anymore. (patch 4/4)
To be sure, I added two tests for cases we didn't cover yet. (patches 1
and 2, these could be applied anyway since they just test the status
quo).
Further improvement could be to always add pci.4 with the next machine
version, but this can be done as a follow up or separate series later
too.
Dominik Csapak (4):
tests: add test with q35 and scsihw2
tests: add test for legacy-igd passthrough
pci: don't try to hotplug bridges
pci: bridges: add bridges to devices up front
src/PVE/QemuServer.pm | 100 +++++-------------
src/PVE/QemuServer/Drive.pm | 2 +-
src/PVE/QemuServer/DriveDevice.pm | 23 +++-
src/PVE/QemuServer/PCI.pm | 68 +++++++++++-
src/PVE/QemuServer/RNG.pm | 4 +-
src/PVE/QemuServer/USB.pm | 8 +-
.../cfg2cmd/linux-hostpci-legacy-igd.conf | 16 +++
.../cfg2cmd/linux-hostpci-legacy-igd.conf.cmd | 38 +++++++
src/test/cfg2cmd/q35-scsihw2.conf | 13 +++
src/test/cfg2cmd/q35-scsihw2.conf.cmd | 37 +++++++
src/test/run_config2command_tests.pl | 1 +
11 files changed, 225 insertions(+), 85 deletions(-)
create mode 100644 src/test/cfg2cmd/linux-hostpci-legacy-igd.conf
create mode 100644 src/test/cfg2cmd/linux-hostpci-legacy-igd.conf.cmd
create mode 100644 src/test/cfg2cmd/q35-scsihw2.conf
create mode 100644 src/test/cfg2cmd/q35-scsihw2.conf.cmd
--
2.47.3
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH qemu-server 1/4] tests: add test with q35 and scsihw2
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
@ 2026-09-07 11:00 ` Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 2/4] tests: add test for legacy-igd passthrough Dominik Csapak
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 11:00 UTC (permalink / raw)
To: pve-devel
this needs the pci.4 bridge, which was not tested at all yet.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
src/test/cfg2cmd/q35-scsihw2.conf | 13 ++++++++++
src/test/cfg2cmd/q35-scsihw2.conf.cmd | 37 +++++++++++++++++++++++++++
2 files changed, 50 insertions(+)
create mode 100644 src/test/cfg2cmd/q35-scsihw2.conf
create mode 100644 src/test/cfg2cmd/q35-scsihw2.conf.cmd
diff --git a/src/test/cfg2cmd/q35-scsihw2.conf b/src/test/cfg2cmd/q35-scsihw2.conf
new file mode 100644
index 00000000..e0452cca
--- /dev/null
+++ b/src/test/cfg2cmd/q35-scsihw2.conf
@@ -0,0 +1,13 @@
+# TEST: Config with q35, Linux & scsi15 with default controller to test scsihw2
+#
+bios: ovmf
+bootdisk: scsi0
+cores: 2
+efidisk0: local:100/vm-100-disk-1.qcow2,size=128K
+machine: q35
+memory: 512
+net0: virtio=2E:01:68:F9:9C:87,bridge=vmbr0
+ostype: l26
+scsi15: local:100/vm-100-disk-2.qcow2,size=1G
+smbios1: uuid=3dd750ce-d910-44d0-9493-525c0be4e687
+vmgenid: 54d1c06c-8f5b-440f-b5b2-6eab1380e13d
diff --git a/src/test/cfg2cmd/q35-scsihw2.conf.cmd b/src/test/cfg2cmd/q35-scsihw2.conf.cmd
new file mode 100644
index 00000000..169539a1
--- /dev/null
+++ b/src/test/cfg2cmd/q35-scsihw2.conf.cmd
@@ -0,0 +1,37 @@
+/usr/bin/kvm \
+ -id 8006 \
+ -name vm8006 \
+ -no-shutdown \
+ -chardev 'socket,id=qmp,path=/var/run/qemu-server/8006.qmp,server=on,wait=off' \
+ -mon 'chardev=qmp,mode=control' \
+ -chardev 'socket,id=qmp-event,path=/var/run/qmeventd.sock,reconnect-ms=5000' \
+ -mon 'chardev=qmp-event,mode=control' \
+ -pidfile /var/run/qemu-server/8006.pid \
+ -daemonize \
+ -smbios 'type=1,uuid=3dd750ce-d910-44d0-9493-525c0be4e687' \
+ -object '{"id":"throttle-drive-efidisk0","limits":{},"qom-type":"throttle-group"}' \
+ -blockdev '{"driver":"raw","file":{"driver":"file","filename":"/usr/share/pve-edk2-firmware//OVMF_CODE.fd"},"node-name":"pflash0","read-only":true}' \
+ -blockdev '{"detect-zeroes":"on","discard":"ignore","driver":"throttle","file":{"cache":{"direct":false,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":false,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vz/images/100/vm-100-disk-1.qcow2","node-name":"e70e3017c5a79fdee5a04aa92ac1e9c","read-only":false},"node-name":"f70e3017c5a79fdee5a04aa92ac1e9c","read-only":false},"node-name":"drive-efidisk0","read-only":false,"throttle-group":"throttle-drive-efidisk0"}' \
+ -global 'ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off' \
+ -smp '2,sockets=1,cores=2,maxcpus=2' \
+ -nodefaults \
+ -boot 'menu=on,strict=on,reboot-timeout=1000,splash=/usr/share/qemu-server/bootsplash.jpg' \
+ -vnc 'unix:/var/run/qemu-server/8006.vnc,password=on' \
+ -cpu kvm64,enforce,+kvm_pv_eoi,+kvm_pv_unhalt,+lahf_lm,+sep \
+ -m 512 \
+ -object '{"id":"throttle-drive-scsi15","limits":{},"qom-type":"throttle-group"}' \
+ -global 'ICH9-LPC.disable_s3=1' \
+ -global 'ICH9-LPC.disable_s4=1' \
+ -readconfig /usr/share/qemu-server/pve-q35-4.0.cfg \
+ -device 'pci-bridge,id=pci.4,chassis_nr=4,bus=pci.1,addr=0x1c' \
+ -device 'vmgenid,guid=54d1c06c-8f5b-440f-b5b2-6eab1380e13d' \
+ -device 'usb-tablet,id=tablet,bus=ehci.0,port=1' \
+ -device 'VGA,id=vga,bus=pcie.0,addr=0x1' \
+ -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3,free-page-reporting=on' \
+ -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
+ -device 'lsi,id=scsihw2,bus=pci.4,addr=0x1' \
+ -blockdev '{"detect-zeroes":"on","discard":"ignore","driver":"throttle","file":{"cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vz/images/100/vm-100-disk-2.qcow2","node-name":"ee7a5fa0313fa9ceafb6db055fb78a4","read-only":false},"node-name":"fe7a5fa0313fa9ceafb6db055fb78a4","read-only":false},"node-name":"drive-scsi15","read-only":false,"throttle-group":"throttle-drive-scsi15"}' \
+ -device 'scsi-hd,bus=scsihw2.0,scsi-id=1,drive=drive-scsi15,id=scsi15,device_id=drive-scsi15,write-cache=on' \
+ -netdev 'type=tap,id=net0,ifname=tap8006i0,script=/usr/libexec/qemu-server/pve-bridge,downscript=/usr/libexec/qemu-server/pve-bridgedown,vhost=on' \
+ -device 'virtio-net-pci,mac=2E:01:68:F9:9C:87,netdev=net0,bus=pci.0,addr=0x12,id=net0,rx_queue_size=1024,tx_queue_size=256,bootindex=300,host_mtu=1500,host_tunnel=off' \
+ -machine 'pflash0=pflash0,pflash1=drive-efidisk0,hpet=off,type=q35+pve0'
--
2.47.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH qemu-server 2/4] tests: add test for legacy-igd passthrough
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 1/4] tests: add test with q35 and scsihw2 Dominik Csapak
@ 2026-09-07 11:00 ` Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 3/4] pci: don't try to hotplug bridges Dominik Csapak
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 11:00 UTC (permalink / raw)
To: pve-devel
this has some implications for pci address calculation (e.g. for pci.2)
so having a test for it will avoid some problems.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
.../cfg2cmd/linux-hostpci-legacy-igd.conf | 16 ++++++++
.../cfg2cmd/linux-hostpci-legacy-igd.conf.cmd | 38 +++++++++++++++++++
src/test/run_config2command_tests.pl | 1 +
3 files changed, 55 insertions(+)
create mode 100644 src/test/cfg2cmd/linux-hostpci-legacy-igd.conf
create mode 100644 src/test/cfg2cmd/linux-hostpci-legacy-igd.conf.cmd
diff --git a/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf b/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf
new file mode 100644
index 00000000..37f3cfee
--- /dev/null
+++ b/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf
@@ -0,0 +1,16 @@
+# TEST: Config with legacy-igd
+bios: ovmf
+bootdisk: scsi0
+cores: 1
+efidisk0: local:100/vm-100-disk-1.qcow2,size=128K
+hostpci0: 00:02.0,legacy-igd=on
+machine: pc
+memory: 512
+net0: virtio=2E:01:68:F9:9C:87,bridge=vmbr0
+numa: 1
+ostype: l26
+scsihw: virtio-scsi-pci
+smbios1: uuid=3dd750ce-d910-44d0-9493-525c0be4e687
+sockets: 2
+vga: none
+vmgenid: 54d1c06c-8f5b-440f-b5b2-6eab1380e13d
diff --git a/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf.cmd b/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf.cmd
new file mode 100644
index 00000000..21dd22ef
--- /dev/null
+++ b/src/test/cfg2cmd/linux-hostpci-legacy-igd.conf.cmd
@@ -0,0 +1,38 @@
+/usr/bin/kvm \
+ -id 8006 \
+ -name vm8006 \
+ -no-shutdown \
+ -chardev 'socket,id=qmp,path=/var/run/qemu-server/8006.qmp,server=on,wait=off' \
+ -mon 'chardev=qmp,mode=control' \
+ -chardev 'socket,id=qmp-event,path=/var/run/qmeventd.sock,reconnect-ms=5000' \
+ -mon 'chardev=qmp-event,mode=control' \
+ -pidfile /var/run/qemu-server/8006.pid \
+ -daemonize \
+ -smbios 'type=1,uuid=3dd750ce-d910-44d0-9493-525c0be4e687' \
+ -object '{"id":"throttle-drive-efidisk0","limits":{},"qom-type":"throttle-group"}' \
+ -blockdev '{"driver":"raw","file":{"driver":"file","filename":"/usr/share/pve-edk2-firmware//OVMF_CODE.fd"},"node-name":"pflash0","read-only":true}' \
+ -blockdev '{"detect-zeroes":"on","discard":"ignore","driver":"throttle","file":{"cache":{"direct":false,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":false,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vz/images/100/vm-100-disk-1.qcow2","node-name":"e70e3017c5a79fdee5a04aa92ac1e9c","read-only":false},"node-name":"f70e3017c5a79fdee5a04aa92ac1e9c","read-only":false},"node-name":"drive-efidisk0","read-only":false,"throttle-group":"throttle-drive-efidisk0"}' \
+ -smp '2,sockets=2,cores=1,maxcpus=2' \
+ -nodefaults \
+ -boot 'menu=on,strict=on,reboot-timeout=1000,splash=/usr/share/qemu-server/bootsplash.jpg' \
+ -vga none \
+ -nographic \
+ -cpu kvm64,enforce,+kvm_pv_eoi,+kvm_pv_unhalt,+lahf_lm,+sep \
+ -m 512 \
+ -object 'memory-backend-ram,id=ram-node0,size=256M' \
+ -numa 'node,nodeid=0,cpus=0,memdev=ram-node0' \
+ -object 'memory-backend-ram,id=ram-node1,size=256M' \
+ -numa 'node,nodeid=1,cpus=1,memdev=ram-node1' \
+ -global 'PIIX4_PM.disable_s3=1' \
+ -global 'PIIX4_PM.disable_s4=1' \
+ -device 'pci-bridge,id=pci.1,chassis_nr=1,bus=pci.0,addr=0x1e' \
+ -device 'pci-bridge,id=pci.2,chassis_nr=2,bus=pci.1,addr=0x1e' \
+ -device 'vmgenid,guid=54d1c06c-8f5b-440f-b5b2-6eab1380e13d' \
+ -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' \
+ -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' \
+ -device 'vfio-pci,host=0000:00:02.0,id=hostpci0,bus=pci.0,addr=0x2' \
+ -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3,free-page-reporting=on' \
+ -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
+ -netdev 'type=tap,id=net0,ifname=tap8006i0,script=/usr/libexec/qemu-server/pve-bridge,downscript=/usr/libexec/qemu-server/pve-bridgedown,vhost=on' \
+ -device 'virtio-net-pci,mac=2E:01:68:F9:9C:87,netdev=net0,bus=pci.0,addr=0x12,id=net0,rx_queue_size=1024,tx_queue_size=256,bootindex=300,host_mtu=1500,host_tunnel=off' \
+ -machine 'pflash0=pflash0,pflash1=drive-efidisk0,hpet=off,type=pc+pve0'
diff --git a/src/test/run_config2command_tests.pl b/src/test/run_config2command_tests.pl
index 47250c67..28f538d3 100755
--- a/src/test/run_config2command_tests.pl
+++ b/src/test/run_config2command_tests.pl
@@ -128,6 +128,7 @@ my $base_env = {
};
my $pci_devs = [
+ "0000:00:02.0",
"0000:00:43.1",
"0000:00:f4.0",
"0000:00:ff.1",
--
2.47.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH qemu-server 3/4] pci: don't try to hotplug bridges
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 1/4] tests: add test with q35 and scsihw2 Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 2/4] tests: add test for legacy-igd passthrough Dominik Csapak
@ 2026-09-07 11:00 ` Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 4/4] pci: bridges: add bridges to devices up front Dominik Csapak
2026-09-07 12:47 ` superseded: [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
4 siblings, 0 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 11:00 UTC (permalink / raw)
To: pve-devel
While bridges can be hotplugged (on PCI on i440fx), no device can be
hotplugged in that afterwards. For that to work the SHPC option would
have to be enabled and the guest must support that. Since this is not
guaranteed to work and bridges don't show up in our config, this could
lead to bridges added that are not represented in the config.
To be on the safe side, simply don't allow hotplugging bridges at all.
Luckily, the only bridge we ever tried hotplugging (since machine
version 2.3) was pci.4 which only houses scsihw2/3/4 at the moment.
These are only used for scsiX where X > 13 and only if the scsihw is an
LSI controller, so not very likely to occur.
This fixes an issue where trying to hotplug a scsi disk with index >=14
on a i440fx machine with an LSI scsi controller would leave the bridge
around after failing to add the scsi controller, and the machine would
subsequently crash on live migration.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
src/PVE/QemuServer.pm | 7 -------
1 file changed, 7 deletions(-)
diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index 149f17be..ab13bc41 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -3992,13 +3992,6 @@ sub vm_deviceplug {
warn $@ if $@;
die $err;
}
- } elsif (!$q35 && $deviceid =~ m/^(pci\.)(\d+)$/) {
- my $bridgeid = $2;
- my $pciaddr = print_pci_addr($deviceid, undef, $arch);
- my $devicefull = "pci-bridge,id=pci.$bridgeid,chassis_nr=$bridgeid$pciaddr";
-
- qemu_deviceadd($vmid, $devicefull);
- qemu_deviceaddverify($vmid, $deviceid);
} else {
die "can't hotplug device '$deviceid'\n";
}
--
2.47.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH qemu-server 4/4] pci: bridges: add bridges to devices up front
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
` (2 preceding siblings ...)
2026-09-07 11:00 ` [PATCH qemu-server 3/4] pci: don't try to hotplug bridges Dominik Csapak
@ 2026-09-07 11:00 ` Dominik Csapak
2026-09-07 12:47 ` superseded: [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
4 siblings, 0 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 11:00 UTC (permalink / raw)
To: pve-devel
Since qemu machine version 2.3, we add the first two bridges by default
(3 in q35), so wiring the bridge adding logic through print_pci_addr was
only necessary in a few (easily checkable) circumstances.
So to not have to pass and collect the bridge devices throughout our
code, instead check those conditions directly and add them upfront.
(This also eliminates the need to insert the bridge devices at specific
point in the commandline via splice/unshift)
The only functional change here should be that we now reject vms with
machine version < 2.3 outright, but QEMU would do so later anyway.
'print_pcie_root_port' was removed from the imports in QemuServer.pm,
since it wasn't used there anymore anyway.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
src/PVE/QemuServer.pm | 93 ++++++++++---------------------
src/PVE/QemuServer/Drive.pm | 2 +-
src/PVE/QemuServer/DriveDevice.pm | 23 +++++++-
src/PVE/QemuServer/PCI.pm | 68 ++++++++++++++++++++--
src/PVE/QemuServer/RNG.pm | 4 +-
src/PVE/QemuServer/USB.pm | 8 +--
6 files changed, 120 insertions(+), 78 deletions(-)
diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index ab13bc41..44965848 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -86,7 +86,7 @@ use PVE::QemuServer::MetaInfo;
use PVE::QemuServer::Monitor qw(mon_cmd qmp_cmd vm_qmp_peer);
use PVE::QemuServer::Network;
use PVE::QemuServer::OVMF;
-use PVE::QemuServer::PCI qw(print_pci_addr print_pcie_addr print_pcie_root_port parse_hostpci);
+use PVE::QemuServer::PCI qw(print_pci_addr print_pcie_addr parse_hostpci get_bridges);
use PVE::QemuServer::PCI::Mdev;
use PVE::QemuServer::QemuImage;
use PVE::QemuServer::QMPHelpers
@@ -1325,7 +1325,6 @@ sub print_netdevice_full {
$conf,
$net,
$netid,
- $bridges,
$use_old_bios_files,
$arch,
$machine_version,
@@ -1337,7 +1336,7 @@ sub print_netdevice_full {
$device = 'virtio-net-pci';
}
- my $pciaddr = print_pci_addr("$netid", $bridges, $arch);
+ my $pciaddr = print_pci_addr("$netid", $arch);
my $tmpstr = "$device,mac=$net->{macaddr},netdev=$netid$pciaddr,id=$netid";
if ($net->{queues} && $net->{queues} > 1 && $net->{model} eq 'virtio') {
# Consider we have N queues, the number of vectors needed is 2 * N + 2, i.e., one per in
@@ -1497,7 +1496,7 @@ my sub map_vga_model {
}
sub print_vga_device {
- my ($conf, $vga, $arch, $machine_version, $id, $qxlnum, $bridges) = @_;
+ my ($conf, $vga, $arch, $machine_version, $id, $qxlnum) = @_;
my $type = map_vga_model($vga->{type}, $arch);
my $vgamem_mb = $vga->{memory};
@@ -1546,7 +1545,7 @@ sub print_vga_device {
# the first display uses pcie.0 bus on q35 machines
$pciaddr = print_pcie_addr($vgaid);
} else {
- $pciaddr = print_pci_addr($vgaid, $bridges, $arch);
+ $pciaddr = print_pci_addr($vgaid, $arch);
}
if ($vga->{type} eq 'virtio-gl') {
@@ -3137,7 +3136,6 @@ sub config_to_command {
my ($machineFlags, $rtcFlags) = ([], []);
my $devices = [];
- my $bridges = {};
my $ostype = $conf->{ostype};
my $winversion = windows_version($ostype);
my $kvm = $conf->{kvm};
@@ -3285,13 +3283,17 @@ sub config_to_command {
push @$cmd, $fixups->@*;
}
+ my $max_scsihw = PVE::QemuServer::DriveDevice::get_max_scsihw_index($conf);
+ if (my $bridges = get_bridges($conf, $arch, $q35, $max_scsihw, $version_guard)) {
+ push @$devices, $bridges->@*;
+ }
+
if ($conf->{vmgenid}) {
push @$devices, '-device', 'vmgenid,guid=' . $conf->{vmgenid};
}
# add usb controllers
- my @usbcontrollers =
- PVE::QemuServer::USB::get_usb_controllers($conf, $bridges, $arch, $machine_version);
+ my @usbcontrollers = PVE::QemuServer::USB::get_usb_controllers($conf, $arch, $machine_version);
push @$devices, @usbcontrollers if @usbcontrollers;
my ($vga, $qxlnum) = get_vga_properties($conf, $arch, $machine_version, $winversion);
@@ -3315,7 +3317,7 @@ sub config_to_command {
# host pci device passthrough
my ($kvm_off, $gpu_passthrough, $legacy_igd, $pci_devices) =
PVE::QemuServer::PCI::print_hostpci_devices(
- $vmid, $conf, $devices, $vga, $winversion, $bridges, $arch, $bootorder, $dry_run,
+ $vmid, $conf, $devices, $vga, $winversion, $arch, $bootorder, $dry_run,
);
# usb devices
@@ -3359,7 +3361,7 @@ sub config_to_command {
}
if (min_version($machine_version, 4, 0) && (my $audio = conf_has_audio($conf))) {
- my $audiopciaddr = print_pci_addr("audio0", $bridges, $arch);
+ my $audiopciaddr = print_pci_addr("audio0", $arch);
my $audio_devs = audio_devs($audio, $audiopciaddr, $machine_version);
push @$devices, @$audio_devs;
}
@@ -3404,7 +3406,7 @@ sub config_to_command {
if ($vga->{type} && $vga->{type} !~ m/^serial\d+$/ && $vga->{type} ne 'none') {
push @$devices, '-device',
- print_vga_device($conf, $vga, $arch, $machine_version, undef, $qxlnum, $bridges);
+ print_vga_device($conf, $vga, $arch, $machine_version, undef, $qxlnum);
push @$cmd, '-display', 'egl-headless,gl=core' if $vga->{type} eq 'virtio-gl'; # VIRGL
@@ -3464,7 +3466,7 @@ sub config_to_command {
push @$devices, '-chardev', "socket,path=$qgasocket,server=on,wait=off,id=qga0";
if (!$guest_agent->{type} || $guest_agent->{type} eq 'virtio') {
- my $pciaddr = print_pci_addr("qga0", $bridges, $arch);
+ my $pciaddr = print_pci_addr("qga0", $arch);
push @$devices, '-device', "virtio-serial,id=qga0$pciaddr";
push @$devices, '-device', 'virtserialport,chardev=qga0,name=org.qemu.guest_agent.0';
} elsif ($guest_agent->{type} eq 'isa') {
@@ -3475,7 +3477,7 @@ sub config_to_command {
my $rng = $conf->{rng0} ? parse_rng($conf->{rng0}) : undef;
if ($rng && $version_guard->(4, 1, 2)) {
my $rng_object = print_rng_object_commandline('rng0', $rng);
- my $rng_device = print_rng_device_commandline('rng0', $rng, $bridges, $arch);
+ my $rng_device = print_rng_device_commandline('rng0', $rng, $arch);
push @$devices, '-object', $rng_object;
push @$devices, '-device', $rng_device;
}
@@ -3489,10 +3491,9 @@ sub config_to_command {
if ($qxlnum > 1) {
if ($winversion) {
for (my $i = 1; $i < $qxlnum; $i++) {
- push @$devices, '-device',
- print_vga_device(
- $conf, $vga, $arch, $machine_version, $i, $qxlnum, $bridges,
- );
+ push @$devices, '-device', print_vga_device(
+ $conf, $vga, $arch, $machine_version, $i, $qxlnum,
+ );
}
} else {
# assume other OS works like Linux
@@ -3506,7 +3507,7 @@ sub config_to_command {
}
}
- my $pciaddr = print_pci_addr("spice", $bridges, $arch);
+ my $pciaddr = print_pci_addr("spice", $arch);
push @$devices, '-device', "virtio-serial,id=spice$pciaddr";
if ($vga->{'clipboard'} && $vga->{'clipboard'} eq 'vnc') {
@@ -3544,7 +3545,7 @@ sub config_to_command {
# enable balloon by default, unless explicitly disabled
if (!defined($conf->{balloon}) || $conf->{balloon}) {
- my $pciaddr = print_pci_addr("balloon0", $bridges, $arch);
+ my $pciaddr = print_pci_addr("balloon0", $arch);
my $ballooncmd = "virtio-balloon-pci,id=balloon0$pciaddr";
$ballooncmd .= ",free-page-reporting=on" if min_version($machine_version, 6, 2);
push @$devices, '-device', $ballooncmd;
@@ -3552,7 +3553,7 @@ sub config_to_command {
if ($conf->{watchdog}) {
my $wdopts = parse_watchdog($conf->{watchdog});
- my $pciaddr = print_pci_addr("watchdog", $bridges, $arch);
+ my $pciaddr = print_pci_addr("watchdog", $arch);
my $watchdog = $wdopts->{model} || 'i6300esb';
push @$devices, '-device', "$watchdog$pciaddr";
push @$devices, '-watchdog-action', $wdopts->{action} if $wdopts->{action};
@@ -3594,7 +3595,7 @@ sub config_to_command {
"scsi$drive->{index}: machine version 4.1~pve2 or higher is required to use more than 14 SCSI disks\n"
if $drive->{index} > 13 && !&$version_guard(4, 1, 2);
- my $pciaddr = print_pci_addr("$controller_prefix$controller", $bridges, $arch);
+ my $pciaddr = print_pci_addr("$controller_prefix$controller", $arch);
my $scsihw_type =
$scsihw =~ m/^virtio-scsi-single/ ? "virtio-scsi-pci" : $scsihw;
@@ -3629,7 +3630,7 @@ sub config_to_command {
if ($drive->{interface} eq 'sata') {
my $controller = int($drive->{index} / $PVE::QemuServer::Drive::MAX_SATA_DISKS);
- my $pciaddr = print_pci_addr("ahci$controller", $bridges, $arch);
+ my $pciaddr = print_pci_addr("ahci$controller", $arch);
push @$devices, '-device', "ahci,id=ahci$controller,multifunction=on$pciaddr"
if !$ahcicontroller->{$controller};
$ahcicontroller->{$controller} = 1;
@@ -3673,10 +3674,9 @@ sub config_to_command {
push @$devices, '-drive', $drive_cmd;
}
- push @$devices, '-device',
- print_drivedevice_full(
- $storecfg, $conf, $vmid, $drive, $bridges, $arch, $machine_type,
- );
+ push @$devices, '-device', print_drivedevice_full(
+ $storecfg, $conf, $vmid, $drive, $arch, $machine_type,
+ );
},
);
@@ -3704,7 +3704,6 @@ sub config_to_command {
$conf,
$d,
$netname,
- $bridges,
$use_old_bios_files,
$arch,
$machine_version,
@@ -3721,7 +3720,7 @@ sub config_to_command {
if ($q35) {
$bus = print_pcie_addr("ivshmem");
} else {
- $bus = print_pci_addr("ivshmem", $bridges, $arch);
+ $bus = print_pci_addr("ivshmem", $arch);
}
my $ivshmem_name = $ivshmem->{name} // $vmid;
@@ -3732,34 +3731,6 @@ sub config_to_command {
"memory-backend-file,id=ivshmem,share=on,mem-path=$path" . ",size=$ivshmem->{size}M";
}
- # pci.4 is nested in pci.1
- $bridges->{1} = 1 if $bridges->{4};
-
- if (!$q35) { # add pci bridges
- if (min_version($machine_version, 2, 3)) {
- $bridges->{1} = 1;
- $bridges->{2} = 1;
- }
- $bridges->{3} = 1 if $scsihw =~ m/^virtio-scsi-single/;
- }
-
- for my $k (sort { $b cmp $a } keys %$bridges) {
- next if $q35 && $k < 4; # q35.cfg already includes bridges up to 3
-
- my $k_name = $k;
- if ($k == 2 && $legacy_igd) {
- $k_name = "$k-igd";
- }
- my $pciaddr = print_pci_addr("pci.$k_name", undef, $arch);
- my $devstr = "pci-bridge,id=pci.$k,chassis_nr=$k$pciaddr";
-
- if ($q35) { # add after -readconfig pve-q35.cfg
- splice @$devices, 2, 0, '-device', $devstr;
- } else {
- unshift @$devices, '-device', $devstr if $k > 0;
- }
- }
-
if (!$kvm) {
push @$machineFlags, 'accel=tcg';
}
@@ -4211,15 +4182,7 @@ sub qemu_deletescsihw {
sub qemu_add_pci_bridge {
my ($storecfg, $conf, $vmid, $device, $arch, $machine_type) = @_;
- my $bridges = {};
-
- my $bridgeid;
-
- print_pci_addr($device, $bridges, $arch);
-
- while (my ($k, $v) = each %$bridges) {
- $bridgeid = $k;
- }
+ my $bridgeid = PVE::QemuServer::PCI::get_bridge_for_device($device);
return 1 if !defined($bridgeid) || $bridgeid < 1;
my $bridge = "pci.$bridgeid";
diff --git a/src/PVE/QemuServer/Drive.pm b/src/PVE/QemuServer/Drive.pm
index b80b7dbb..17c46f36 100644
--- a/src/PVE/QemuServer/Drive.pm
+++ b/src/PVE/QemuServer/Drive.pm
@@ -152,7 +152,7 @@ sub get_path_and_format {
}
my $MAX_IDE_DISKS = 4;
-my $MAX_SCSI_DISKS = 31;
+our $MAX_SCSI_DISKS = 31;
my $MAX_VIRTIO_DISKS = 16;
our $MAX_SATA_DISKS = 6;
our $MAX_UNUSED_DISKS = 256;
diff --git a/src/PVE/QemuServer/DriveDevice.pm b/src/PVE/QemuServer/DriveDevice.pm
index 37b611f0..bff43dc4 100644
--- a/src/PVE/QemuServer/DriveDevice.pm
+++ b/src/PVE/QemuServer/DriveDevice.pm
@@ -27,6 +27,25 @@ our @EXPORT_OK = qw(
scsihw_infos
);
+# Gets the maximum scsihw index that will be used
+sub get_max_scsihw_index {
+ my ($conf) = @_;
+
+ my $max_index = 0;
+
+ for (my $i = 0; $i < $PVE::QemuServer::Drive::MAX_SCSI_DISKS; $i++) {
+ next if !defined($conf->{"scsi$i"});
+ my (undef, $index, $prefix) = scsihw_infos($conf->{scsihw}, $i);
+ last if $prefix ne 'scsihw'; # must be the same for all
+
+ if ($index > $max_index) {
+ $max_index = $index;
+ }
+ }
+
+ return $max_index;
+}
+
sub scsihw_infos {
my ($scsihw, $drive_index) = @_;
@@ -50,7 +69,7 @@ sub scsihw_infos {
}
sub print_drivedevice_full {
- my ($storecfg, $conf, $vmid, $drive, $bridges, $arch, $machine_type) = @_;
+ my ($storecfg, $conf, $vmid, $drive, $arch, $machine_type) = @_;
my $device = '';
my $maxdev = 0;
@@ -61,7 +80,7 @@ sub print_drivedevice_full {
my $drive_id = PVE::QemuServer::Drive::get_drive_id($drive);
if ($drive->{interface} eq 'virtio') {
- my $pciaddr = print_pci_addr("$drive_id", $bridges, $arch);
+ my $pciaddr = print_pci_addr("$drive_id", $arch);
$device = 'virtio-blk-pci';
# for the switch to -blockdev, there is no blockdev for 'none'
if (!min_version($machine_version, 10, 0) || $drive->{file} ne 'none') {
diff --git a/src/PVE/QemuServer/PCI.pm b/src/PVE/QemuServer/PCI.pm
index 0b67943c..a2c0f60a 100644
--- a/src/PVE/QemuServer/PCI.pm
+++ b/src/PVE/QemuServer/PCI.pm
@@ -21,6 +21,7 @@ our @EXPORT_OK = qw(
print_pcie_addr
print_pcie_root_port
parse_hostpci
+ get_bridges
);
our $MAX_HOSTPCI_DEVICES = 16;
@@ -292,8 +293,19 @@ my $get_addr_mapping_from_id = sub {
return { bus => $d->{bus}, addr => sprintf("0x%x", $d->{addr}) };
};
+sub get_bridge_for_device {
+ my ($id) = @_;
+
+ my $map = get_pci_addr_map();
+ if (my $d = $get_addr_mapping_from_id->($map, $id)) {
+ return $d->{bus};
+ }
+
+ return;
+}
+
sub print_pci_addr {
- my ($id, $bridges, $arch) = @_;
+ my ($id, $arch) = @_;
die "aarch64 cannot use IDE devices\n" if $arch eq 'aarch64' && $id =~ /^ide/;
@@ -306,7 +318,6 @@ sub print_pci_addr {
my $busname = $arch eq 'aarch64' && $d->{bus} eq 0 ? 'pcie' : 'pci';
$res = ",bus=$busname.$d->{bus},addr=$d->{addr}";
- $bridges->{ $d->{bus} } = 1 if $bridges;
}
return $res;
@@ -617,7 +628,7 @@ sub choose_hostpci_devices {
}
sub print_hostpci_devices {
- my ($vmid, $conf, $devices, $vga, $winversion, $bridges, $arch, $bootorder, $dry_run) = @_;
+ my ($vmid, $conf, $devices, $vga, $winversion, $arch, $bootorder, $dry_run) = @_;
my $kvm_off = 0;
my $gpu_passthrough = 0;
@@ -648,7 +659,7 @@ sub print_hostpci_devices {
}
} else {
my $pci_name = $d->{'legacy-igd'} ? 'legacy-igd' : $id;
- $pciaddr = print_pci_addr($pci_name, $bridges, $arch);
+ $pciaddr = print_pci_addr($pci_name, $arch);
}
my $num_devices = scalar($d->{ids}->@*);
@@ -871,4 +882,53 @@ sub reserve_pci_usage {
die $@ if $@;
}
+# Returns a list of bridge devices which are necessary for the remaining
+# devices.
+sub get_bridges {
+ my ($conf, $arch, $q35, $max_scsihw, $version_guard) = @_;
+
+ # older machine versions didn't add the bridges by default. They're
+ # not supported by modern qemu anymore, so don't try to start them.
+ if (!$version_guard->(2, 3)) {
+ die "unsupported old machine version detected\n";
+ }
+
+ my $bridges = {
+ # 0 => 1, always present
+ 1 => 1,
+ 2 => 1,
+ };
+
+ $bridges->{3} = 1 if ($conf->{scsihw} // '') =~ m/^virtio-scsi-single/;
+
+ # some scsi controllers can only have 7 scsi disks per controller,
+ # so scsi14 and upwards need scsihw2,3,4 which live on bridge 4
+ $bridges->{4} = 1 if $max_scsihw > 1;
+
+ # use cheap legacy igd check instead full parse_hostpci
+ my $legacy_igd = 0;
+ for (my $i = 0; $i < $MAX_HOSTPCI_DEVICES; $i++) {
+ next if !defined($conf->{"hostpci$i"});
+ next if $conf->{"hostpci$i"} !~ m/legacy-igd=(?:on|1|yes|true)/i;
+ $legacy_igd = 1;
+ last;
+ }
+
+ my $devices = [];
+ for my $k (sort { $a <=> $b } keys %$bridges) {
+ next if $q35 && $k < 4; # q35.cfg already includes bridges up to 3
+
+ my $k_name = $k;
+ if ($k == 2 && $legacy_igd) {
+ $k_name = "$k-igd";
+ }
+ my $pciaddr = print_pci_addr("pci.$k_name", $arch);
+ my $devstr = "pci-bridge,id=pci.$k,chassis_nr=$k$pciaddr";
+
+ push @$devices, '-device', $devstr;
+ }
+
+ return $devices;
+}
+
1;
diff --git a/src/PVE/QemuServer/RNG.pm b/src/PVE/QemuServer/RNG.pm
index eb477a5d..f854dd50 100644
--- a/src/PVE/QemuServer/RNG.pm
+++ b/src/PVE/QemuServer/RNG.pm
@@ -87,7 +87,7 @@ sub check_rng_source {
}
sub print_rng_device_commandline {
- my ($id, $rng, $bridges, $arch) = @_;
+ my ($id, $rng, $arch) = @_;
die "no rng device specified\n" if !$rng;
@@ -98,7 +98,7 @@ sub print_rng_device_commandline {
$limiter_str = ",max-bytes=$max_bytes,period=$period";
}
- my $rng_addr = print_pci_addr($id, $bridges, $arch);
+ my $rng_addr = print_pci_addr($id, $arch);
return "virtio-rng-pci,rng=$id$limiter_str$rng_addr";
}
diff --git a/src/PVE/QemuServer/USB.pm b/src/PVE/QemuServer/USB.pm
index c9408a42..d75507e4 100644
--- a/src/PVE/QemuServer/USB.pm
+++ b/src/PVE/QemuServer/USB.pm
@@ -120,7 +120,7 @@ my sub assert_usb_index_is_useable {
}
sub get_usb_controllers {
- my ($conf, $bridges, $arch, $machine_version) = @_;
+ my ($conf, $arch, $machine_version) = @_;
my $devices = [];
my $pciaddr = "";
@@ -134,10 +134,10 @@ sub get_usb_controllers {
my $is_q35 = PVE::QemuServer::Machine::machine_type_is_q35($conf);
if ($arch eq 'aarch64') {
- $pciaddr = print_pci_addr('ehci', $bridges, $arch);
+ $pciaddr = print_pci_addr('ehci', $arch);
push @$devices, '-device', "usb-ehci,id=ehci$pciaddr";
} elsif (!$is_q35) {
- $pciaddr = print_pci_addr("piix3", $bridges, $arch);
+ $pciaddr = print_pci_addr("piix3", $arch);
push @$devices, '-device', "piix3-usb-uhci,id=uhci$pciaddr.0x2";
}
@@ -157,7 +157,7 @@ sub get_usb_controllers {
push @$devices, '-readconfig', '/usr/share/qemu-server/pve-usb.cfg';
}
- $pciaddr = print_pci_addr("xhci", $bridges, $arch);
+ $pciaddr = print_pci_addr("xhci", $arch);
if ($use_qemu_xhci && $any_usb) {
push @$devices, '-device', print_qemu_xhci_controller($pciaddr);
} elsif ($use_usb3) {
--
2.47.3
^ permalink raw reply related [flat|nested] 6+ messages in thread
* superseded: [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
` (3 preceding siblings ...)
2026-09-07 11:00 ` [PATCH qemu-server 4/4] pci: bridges: add bridges to devices up front Dominik Csapak
@ 2026-09-07 12:47 ` Dominik Csapak
4 siblings, 0 replies; 6+ messages in thread
From: Dominik Csapak @ 2026-09-07 12:47 UTC (permalink / raw)
To: pve-devel
superseded by v2:
https://lore.proxmox.com/pve-devel/20260907124335.2822329-1-d.csapak@proxmox.com/T/#t
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-09-07 12:47 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-09-07 11:00 [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 1/4] tests: add test with q35 and scsihw2 Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 2/4] tests: add test for legacy-igd passthrough Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 3/4] pci: don't try to hotplug bridges Dominik Csapak
2026-09-07 11:00 ` [PATCH qemu-server 4/4] pci: bridges: add bridges to devices up front Dominik Csapak
2026-09-07 12:47 ` superseded: [PATCH qemu-server 0/4] pci: bridges: cleanup and hotplug fix Dominik Csapak
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