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From: Dominik Csapak <d.csapak@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH qemu-server 3/4] pci: don't try to hotplug bridges
Date: Mon,  7 Sep 2026 13:00:20 +0200	[thread overview]
Message-ID: <20260907110621.2122120-4-d.csapak@proxmox.com> (raw)
In-Reply-To: <20260907110621.2122120-1-d.csapak@proxmox.com>

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





  parent reply	other threads:[~2026-09-07 11:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
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 [this message]
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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