[pve-devel] [PATCH qemu-server] vm start: fix migration regression with Windows by only enrolling EFI certs on cold start

[pve-devel] [PATCH qemu-server] vm start: fix migration regression with Windows by only enrolling EFI certs on cold start

[Fiona Ebner]

The EFI disk can only be exclusively accessed during cold start, so
skip check_efi_vars() for migration and resume from hibernation.

Also, check_efi_vars() might write the VM configuration, which also
cannot be done in the context of migration at this stage, because the
configuration does not exist on the target yet and it would result in:

> close (rename) atomic file '/etc/pve/nodes/squid176/qemu-server/106.conf' failed: File exists

Fixes: c5b3a314 ("fix #6985: ovmf: auto-enroll Microsoft UEFI CA 2023 for Windows")
Reported-by: Friedrich Weber <f.weber@proxmox.com>
Suggested-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 src/PVE/QemuServer.pm | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index 9946e445..b39157af 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -5610,7 +5610,11 @@ sub vm_start_nolock {
         my $storage_hints = generate_storage_hints($conf, 1);
         PVE::Storage::activate_volumes($storecfg, $vollist, undef, $storage_hints);
 
-        check_efi_vars($storecfg, $vmid, $conf) if $conf->{bios} && $conf->{bios} eq 'ovmf';
+        # Can only exclusively access EFI disk during cold start. Also, check_efi_vars() might write
+        # the configuration, which must not be done at this stage of migration on the target.
+        if (!$statefile && !$resume && $conf->{bios} && $conf->{bios} eq 'ovmf') {
+            check_efi_vars($storecfg, $vmid, $conf);
+        }
 
         # Note that for certain cases like templates, the configuration is minimized, so need to ensure
         # the rest of the function here uses the same configuration that was used to build the command
-- 
2.47.3



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[pve-devel] applied: [PATCH qemu-server] vm start: fix migration regression with Windows by only enrolling EFI certs on cold start

[Thomas Lamprecht]

On Mon, 17 Nov 2025 13:58:42 +0100, Fiona Ebner wrote:
> The EFI disk can only be exclusively accessed during cold start, so
> skip check_efi_vars() for migration and resume from hibernation.
> 
> Also, check_efi_vars() might write the VM configuration, which also
> cannot be done in the context of migration at this stage, because the
> configuration does not exist on the target yet and it would result in:
> 
> [...]

Applied, thanks!

[1/1] vm start: fix migration regression with Windows by only enrolling EFI certs on cold start
      commit: a3e0946f447926ffbb811d686e0bb2b78db89e96


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