[pve-devel] [PATCH qemu-server v2] fix #3784: Parameter for guest vIOMMU

[Markus Frank]

added a Parameter for vIOMMU so nobody has to use a github-script
or change the kvm command on every vm boot.
The args parameter doesn't work because the -device parameter(kvm)
with intel-iommu has to be placed before the other arguments.

vIOMMU enables the option to pass through pci devices to guest-vms
in guest-vms for nested Virtualisation.

Signed-off-by: Markus Frank <m.frank at proxmox.com>
---
v2:
* moved viommu-parameter inside of machine_fmt and added it the new
parameter machine_properties
new Config -> machine_properties: viommu=1,etc
* check if kvm and q35 are set

 PVE/QemuServer.pm | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 6a9f6b3..5878dfc 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -134,6 +134,15 @@ sub nodename {
     return $nodename_cache;
 }
 
+my $machine_fmt = {
+    viommu => {
+	type => 'boolean',
+	description => "enable guest vIOMMU (needs kvm to be enabled and q35 to be set as machine)",
+	default => 0,
+	optional => 1,
+    },
+};
+
 my $watchdog_fmt = {
     model => {
 	default_key => 1,
@@ -647,6 +656,12 @@ EODESCR
 	    ." remove disk operations.",
 	default => 0,
     },
+    machine_properties => {
+	optional => 1,
+	type => 'string',
+	format => $machine_fmt,
+	description => "Sets machine parameters for viommu for Example",
+    },
     bios => {
 	optional => 1,
 	type => 'string',
@@ -3433,6 +3448,10 @@ sub config_to_command {
     my $winversion = windows_version($ostype);
     my $kvm = $conf->{kvm};
     my $nodename = nodename();
+    my $machine_properties_str = $conf->{machine_properties} // '';
+
+    my $machine_properties = parse_property_string($machine_fmt, $machine_properties_str);
+
 
     my $arch = get_vm_arch($conf);
     my $kvm_binary = get_command_for_arch($arch);
@@ -3487,6 +3506,14 @@ sub config_to_command {
     my $use_old_bios_files = undef;
     ($use_old_bios_files, $machine_type) = qemu_use_old_bios_files($machine_type);
 
+    if ($machine_properties->{viommu} && (!$kvm || !$q35)) {
+	die "to use vIOMMU please enable kvm and set the machine type to q35";
+    }
+
+    if ($machine_properties->{viommu}) {
+	push @$devices, '-device', 'intel-iommu,intremap=on,caching-mode=on';
+    }
+
     push @$cmd, $kvm_binary;
 
     push @$cmd, '-id', $vmid;
@@ -4027,6 +4054,10 @@ sub config_to_command {
     }
     push @$machineFlags, "type=${machine_type_min}";
 
+    if ($machine_properties->{viommu}) {
+	push @$machineFlags, 'kernel-irqchip=split';
+    }
+
     push @$cmd, @$devices;
     push @$cmd, '-rtc', join(',', @$rtcFlags) if scalar(@$rtcFlags);
     push @$cmd, '-machine', join(',', @$machineFlags) if scalar(@$machineFlags);
-- 
2.30.2