[pve-devel] [PATCH v3 qemu-server 0/2] add virtio-mem support

[pve-devel] [PATCH v3 qemu-server 0/2] add virtio-mem support

[Alexandre Derumier]

This patch add virtio-mem support, through a new maxmemory option.

a 4GB static memory is needed for DMA+boot memory, as this memory
is almost always un-unpluggeable.

1 virtio-mem pci device is setup for each numa node on pci.4 bridge

virtio-mem use a fixed blocksize with 32k max blocksize,
so blocksize is computed from the maxmemory/32000 with a minimum of
2MB to map THP.
(lower blocksize = more chance to unplug memory).

guests tested:
- ubuntu 22.04 : kernel 5.15 : works out of the box
- debian11: kernel 5.10 : don't display new memory value

more info about virtio-mem:
https://virtio-mem.gitlab.io/


Changelog v2:

- Allow only multiple of 32MB for memory. With lower values, guest sometimes
  hang.  I have tested with step of 32MB from 4G to 768G, it's working fine.

- rebase tests

Changelog v3:

- rename "maxmemory" option to "memory_max"
- rebase to last git and handle the max_mem changes with phys-bits


Alexandre Derumier (2):
  add virtio-mem support
  tests: add virtio-mem tests

 PVE/QemuServer.pm                           |   9 +-
 PVE/QemuServer/Memory.pm                    | 141 +++++++++++++++-----
 PVE/QemuServer/PCI.pm                       |   8 ++
 test/cfg2cmd/simple-virtio-mem-big.conf     |  12 ++
 test/cfg2cmd/simple-virtio-mem-big.conf.cmd |  59 ++++++++
 test/cfg2cmd/simple-virtio-mem.conf         |  13 ++
 test/cfg2cmd/simple-virtio-mem.conf.cmd     |  31 +++++
 7 files changed, 241 insertions(+), 32 deletions(-)
 create mode 100644 test/cfg2cmd/simple-virtio-mem-big.conf
 create mode 100644 test/cfg2cmd/simple-virtio-mem-big.conf.cmd
 create mode 100644 test/cfg2cmd/simple-virtio-mem.conf
 create mode 100644 test/cfg2cmd/simple-virtio-mem.conf.cmd

-- 
2.30.2

[pve-devel] [PATCH v3 qemu-server 1/2] add virtio-mem support

[Alexandre Derumier]

This patch add virtio-mem support, through a new maxmemory option.

a 4GB static memory is needed for DMA+boot memory, as this memory
is almost always un-unpluggeable.

1 virtio-mem pci device is setup for each numa node on pci.4 bridge

virtio-mem use a fixed blocksize with 32k max blocksize,
so blocksize is computed from the maxmemory/32000 with a minimum of
2MB to map THP.
(lower blocksize = more chance to unplug memory).

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
---
 PVE/QemuServer.pm        |   9 ++-
 PVE/QemuServer/Memory.pm | 141 ++++++++++++++++++++++++++++++---------
 PVE/QemuServer/PCI.pm    |   8 +++
 3 files changed, 126 insertions(+), 32 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 9a20647..d0f6d1f 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -338,6 +338,13 @@ my $confdesc = {
 	maximum => 262144,
 	default => 'cgroup v1: 1024, cgroup v2: 100',
     },
+    'memory_max' => {
+	optional => 1,
+	type => 'integer',
+	description => "Max hotpluggable virtio-mem memory",
+	minimum => 4096,
+	default => undef,
+    },
     memory => {
 	optional => 1,
 	type => 'integer',
@@ -3858,7 +3865,7 @@ sub config_to_command {
 	push @$cmd, get_cpu_options($conf, $arch, $kvm, $kvm_off, $machine_version, $winversion, $gpu_passthrough);
     }
 
-    PVE::QemuServer::Memory::config($conf, $vmid, $sockets, $cores, $defaults, $hotplug_features, $cmd);
+    PVE::QemuServer::Memory::config($conf, $vmid, $sockets, $cores, $defaults, $hotplug_features, $cmd, $devices, $bridges, $arch, $machine_type);
 
     push @$cmd, '-S' if $conf->{freeze};
 
diff --git a/PVE/QemuServer/Memory.pm b/PVE/QemuServer/Memory.pm
index 013917e..ed7eff6 100644
--- a/PVE/QemuServer/Memory.pm
+++ b/PVE/QemuServer/Memory.pm
@@ -8,9 +8,45 @@ use PVE::Exception qw(raise raise_param_exc);
 
 use PVE::QemuServer;
 use PVE::QemuServer::Monitor qw(mon_cmd);
+use PVE::QemuServer::PCI qw(print_pci_addr);
 
 my $MAX_NUMA = 8;
-my $STATICMEM = 1024;
+
+my sub get_static_mem {
+    my ($conf, $defaults) = @_;
+
+    my $sockets = 1;
+    $sockets = $conf->{smp} if $conf->{smp}; # old style - no longer iused
+    $sockets = $conf->{sockets} if $conf->{sockets};
+    my $hotplug_features = PVE::QemuServer::parse_hotplug_features(defined($conf->{hotplug}) ? $conf->{hotplug} : '1');
+
+    my $static_memory = 0;
+
+    if ($hotplug_features->{memory} || $conf->{'memory_max'}) {
+       $static_memory = 1024;
+       $static_memory = $static_memory * $sockets if ($conf->{hugepages} && $conf->{hugepages} == 1024);
+       $static_memory = 4096 if $conf->{'memory_max'};
+    } else {
+       $static_memory = $conf->{memory} || $defaults->{memory};
+    }
+
+    return $static_memory;
+}
+
+my sub get_virtiomem_block_size {
+    my ($conf, $static_memory) = @_;
+
+    my $maxmemory = $conf->{'memory_max'};
+    return undef if !$maxmemory;
+
+    #virtiomem can map 32000 block size. try to use lowerst blocksize, lower = more chance to unplug memory.
+    my $blocksize = ($maxmemory - $static_memory) / 32000;
+    #round next power of 2
+    $blocksize = 2**(int(log($blocksize)/log(2))+1);
+    #2MB is the minimum to be aligned with THP
+    $blocksize = 2 if $blocksize < 2;
+    return $blocksize;
+}
 
 my $_host_bits;
 my sub get_host_phys_address_bits {
@@ -58,7 +94,14 @@ my sub get_max_mem {
     # remove 20 bits to get MB and half that as QEMU needs some overhead
     my $bits_to_max_mem = int(1 << ($bits - 21));
 
-    return $bits_to_max_mem > 4*1024*1024 ? 4*1024*1024 : $bits_to_max_mem;
+    my $max_mem = $bits_to_max_mem > 4*1024*1024 ? 4*1024*1024 : $bits_to_max_mem;
+
+    if($conf->{'memory_max'}) {
+	die "memory_max can't be bigger than $max_mem MB" if $conf->{'memory_max'} > $max_mem;
+	return $conf->{'memory_max'};
+    }
+
+    return $max_mem;
 }
 
 sub get_numa_node_list {
@@ -152,6 +195,8 @@ sub foreach_reverse_dimm {
     }
 }
 
+
+
 sub qemu_memory_hotplug {
     my ($vmid, $conf, $defaults, $opt, $value) = @_;
 
@@ -164,14 +209,46 @@ sub qemu_memory_hotplug {
     $value = $defaults->{memory} if !$value;
     return $value if $value == $memory;
 
-    my $static_memory = $STATICMEM;
-    $static_memory = $static_memory * $sockets if ($conf->{hugepages} && $conf->{hugepages} == 1024);
+    my $static_memory = get_static_mem($conf, $defaults);
+    my $max_mem = get_max_mem($conf);
 
     die "memory can't be lower than $static_memory MB" if $value < $static_memory;
-    my $MAX_MEM = get_max_mem($conf);
-    die "you cannot add more memory than max mem $MAX_MEM MB!\n" if $memory > $MAX_MEM;
+    die "you cannot add more memory than max mem $max_mem MB!\n" if $value > $max_mem;
+
+   if ($conf->{'memory_max'}) {
+
+	die "memory size need to be multiple of 32MB when memory_max is defined" if $value % 32 != 0;
+
+	my $requested_size = ($value - $static_memory) / $sockets * 1024 * 1024;
 
-    if ($value > $memory) {
+	my $totalsize = $static_memory;
+	my $err = undef;
+
+	for (my $i = 0; $i < $sockets; $i++)  {
+
+	    my $id = "virtiomem$i";
+	    my $retry = 0;
+	    mon_cmd($vmid, 'qom-set', path => "/machine/peripheral/$id", property => "requested-size", value => int($requested_size));
+
+	    my $size = 0;
+	    while (1) {
+		sleep 1;
+		$size = mon_cmd($vmid, 'qom-get', path => "/machine/peripheral/$id", property => "size");
+		$err = 1 if $retry > 5;
+		last if $size eq $requested_size || $retry > 5;
+		$retry++;
+	    }
+	    $totalsize += ($size / 1024 / 1024 );
+	}
+	#update conf after each succesful module unplug
+	if($err) {
+	    $conf->{memory} = $totalsize;
+	    PVE::QemuConfig->write_config($vmid, $conf);
+	    raise_param_exc({ 'memory' => "error modify virtio memory" }) if $err;
+	}
+	return $totalsize;
+
+    } elsif($value > $memory) {
 
 	my $numa_hostmap;
 
@@ -266,33 +343,27 @@ sub qemu_dimm_list {
 }
 
 sub config {
-    my ($conf, $vmid, $sockets, $cores, $defaults, $hotplug_features, $cmd) = @_;
+    my ($conf, $vmid, $sockets, $cores, $defaults, $hotplug_features, $cmd, $devices, $bridges, $arch, $machine_type) = @_;
 
     my $memory = $conf->{memory} || $defaults->{memory};
-    my $static_memory = 0;
+    my $static_memory = get_static_mem($conf, $defaults);
 
-    if ($hotplug_features->{memory}) {
+    if ($hotplug_features->{memory} || $conf->{'memory_max'}) {
 	die "NUMA needs to be enabled for memory hotplug\n" if !$conf->{numa};
-	my $MAX_MEM = get_max_mem($conf);
-	die "Total memory is bigger than ${MAX_MEM}MB\n" if $memory > $MAX_MEM;
+	my $max_mem = get_max_mem($conf);
+	die "Total memory is bigger than ${max_mem}MB\n" if $memory > $max_mem;
 
 	for (my $i = 0; $i < $MAX_NUMA; $i++) {
 	    die "cannot enable memory hotplugging with custom NUMA topology\n"
 		if $conf->{"numa$i"};
 	}
 
-	my $sockets = 1;
-	$sockets = $conf->{sockets} if $conf->{sockets};
-
-	$static_memory = $STATICMEM;
-	$static_memory = $static_memory * $sockets if ($conf->{hugepages} && $conf->{hugepages} == 1024);
-
-	die "minimum memory must be ${static_memory}MB\n" if($memory < $static_memory);
-	push @$cmd, '-m', "size=${static_memory},slots=255,maxmem=${MAX_MEM}M";
+	die "memory size need to be multiple of 32MB when memory_max is defined" if $conf->{'memory_max'} && ($memory % 32 != 0);
+	my $cmdstr = "size=${static_memory},maxmem=${max_mem}M";
+	$cmdstr .= ",slots=255" if !$conf->{'memory_max'};
+	push @$cmd, '-m', $cmdstr;
 
     } else {
-
-	$static_memory = $memory;
 	push @$cmd, '-m', $static_memory;
     }
 
@@ -359,7 +430,21 @@ sub config {
 	}
     }
 
-    if ($hotplug_features->{memory}) {
+    if ($conf->{'memory_max'}) {
+	my $node_maxmem = ($conf->{'memory_max'} - $static_memory) / $sockets;
+	my $node_mem = ($memory - $static_memory) / $sockets;
+	my $blocksize = get_virtiomem_block_size($conf, $static_memory);
+
+	for (my $i = 0; $i < $sockets; $i++)  {
+
+	    my $id = "virtiomem$i";
+	    my $pciaddr = print_pci_addr($id, $bridges, $arch, $machine_type);
+	    my $mem_object = print_mem_object($conf, "mem-$id", $node_maxmem);
+
+	    push @$cmd, "-object" , $mem_object;
+	    push @$devices, "-device", "virtio-mem-pci,block-size=${blocksize}M,requested-size=${node_mem}M,id=$id,memdev=mem-$id,node=$i$pciaddr";
+	}
+    } elsif ($hotplug_features->{memory}) {
 	foreach_dimm($conf, $vmid, $memory, $sockets, sub {
 	    my ($conf, $vmid, $name, $dimm_size, $numanode, $current_size, $memory) = @_;
 
@@ -485,20 +570,14 @@ sub hugepages_topology {
 
     my $defaults = PVE::QemuServer::load_defaults();
     my $memory = $conf->{memory} || $defaults->{memory};
-    my $static_memory = 0;
+    my $static_memory = get_static_mem($conf, $defaults);
+
     my $sockets = 1;
     $sockets = $conf->{smp} if $conf->{smp}; # old style - no longer iused
     $sockets = $conf->{sockets} if $conf->{sockets};
     my $numa_custom_topology = undef;
     my $hotplug_features = PVE::QemuServer::parse_hotplug_features(defined($conf->{hotplug}) ? $conf->{hotplug} : '1');
 
-    if ($hotplug_features->{memory}) {
-	$static_memory = $STATICMEM;
-	$static_memory = $static_memory * $sockets if ($conf->{hugepages} && $conf->{hugepages} == 1024);
-    } else {
-	$static_memory = $memory;
-    }
-
     #custom numa topology
     for (my $i = 0; $i < $MAX_NUMA; $i++) {
 	next if !$conf->{"numa$i"};
diff --git a/PVE/QemuServer/PCI.pm b/PVE/QemuServer/PCI.pm
index a18b974..0187c74 100644
--- a/PVE/QemuServer/PCI.pm
+++ b/PVE/QemuServer/PCI.pm
@@ -249,6 +249,14 @@ sub get_pci_addr_map {
 	'scsihw2' => { bus => 4, addr => 1 },
 	'scsihw3' => { bus => 4, addr => 2 },
 	'scsihw4' => { bus => 4, addr => 3 },
+	'virtiomem0' => { bus => 4, addr => 4 },
+	'virtiomem1' => { bus => 4, addr => 5 },
+	'virtiomem2' => { bus => 4, addr => 6 },
+	'virtiomem3' => { bus => 4, addr => 7 },
+	'virtiomem4' => { bus => 4, addr => 8 },
+	'virtiomem5' => { bus => 4, addr => 9 },
+	'virtiomem6' => { bus => 4, addr => 10 },
+	'virtiomem7' => { bus => 4, addr => 11 },
     } if !defined($pci_addr_map);
     return $pci_addr_map;
 }
-- 
2.30.2

[pve-devel] [PATCH v3 qemu-server 2/2] tests: add virtio-mem tests

[Alexandre Derumier]

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
---
 test/cfg2cmd/simple-virtio-mem-big.conf     | 12 +++++
 test/cfg2cmd/simple-virtio-mem-big.conf.cmd | 59 +++++++++++++++++++++
 test/cfg2cmd/simple-virtio-mem.conf         | 13 +++++
 test/cfg2cmd/simple-virtio-mem.conf.cmd     | 31 +++++++++++
 4 files changed, 115 insertions(+)
 create mode 100644 test/cfg2cmd/simple-virtio-mem-big.conf
 create mode 100644 test/cfg2cmd/simple-virtio-mem-big.conf.cmd
 create mode 100644 test/cfg2cmd/simple-virtio-mem.conf
 create mode 100644 test/cfg2cmd/simple-virtio-mem.conf.cmd

diff --git a/test/cfg2cmd/simple-virtio-mem-big.conf b/test/cfg2cmd/simple-virtio-mem-big.conf
new file mode 100644
index 0000000..964620f
--- /dev/null
+++ b/test/cfg2cmd/simple-virtio-mem-big.conf
@@ -0,0 +1,12 @@
+# TEST: virtio-mem with 128GB ram && 8 numa nodes
+bootdisk: scsi0
+cores: 1
+memory: 8192
+memory_max: 131072
+name: simple
+numa: 1
+ostype: l26
+scsihw: virtio-scsi-pci
+smbios1: uuid=7b10d7af-b932-4c66-b2c3-3996152ec465
+sockets: 8
+vmgenid: c773c261-d800-4348-1010-1010add53cf8
diff --git a/test/cfg2cmd/simple-virtio-mem-big.conf.cmd b/test/cfg2cmd/simple-virtio-mem-big.conf.cmd
new file mode 100644
index 0000000..a09c750
--- /dev/null
+++ b/test/cfg2cmd/simple-virtio-mem-big.conf.cmd
@@ -0,0 +1,59 @@
+/usr/bin/kvm \
+  -id 8006 \
+  -name 'simple,debug-threads=on' \
+  -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=5' \
+  -mon 'chardev=qmp-event,mode=control' \
+  -pidfile /var/run/qemu-server/8006.pid \
+  -daemonize \
+  -smbios 'type=1,uuid=7b10d7af-b932-4c66-b2c3-3996152ec465' \
+  -smp '8,sockets=8,cores=1,maxcpus=8' \
+  -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 'size=4096,maxmem=131072M' \
+  -object 'memory-backend-ram,id=ram-node0,size=512M' \
+  -numa 'node,nodeid=0,cpus=0,memdev=ram-node0' \
+  -object 'memory-backend-ram,id=ram-node1,size=512M' \
+  -numa 'node,nodeid=1,cpus=1,memdev=ram-node1' \
+  -object 'memory-backend-ram,id=ram-node2,size=512M' \
+  -numa 'node,nodeid=2,cpus=2,memdev=ram-node2' \
+  -object 'memory-backend-ram,id=ram-node3,size=512M' \
+  -numa 'node,nodeid=3,cpus=3,memdev=ram-node3' \
+  -object 'memory-backend-ram,id=ram-node4,size=512M' \
+  -numa 'node,nodeid=4,cpus=4,memdev=ram-node4' \
+  -object 'memory-backend-ram,id=ram-node5,size=512M' \
+  -numa 'node,nodeid=5,cpus=5,memdev=ram-node5' \
+  -object 'memory-backend-ram,id=ram-node6,size=512M' \
+  -numa 'node,nodeid=6,cpus=6,memdev=ram-node6' \
+  -object 'memory-backend-ram,id=ram-node7,size=512M' \
+  -numa 'node,nodeid=7,cpus=7,memdev=ram-node7' \
+  -object 'memory-backend-ram,id=mem-virtiomem0,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem1,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem2,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem3,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem4,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem5,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem6,size=15872M' \
+  -object 'memory-backend-ram,id=mem-virtiomem7,size=15872M' \
+  -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.0,addr=0x1f' \
+  -device 'pci-bridge,id=pci.4,chassis_nr=4,bus=pci.1,addr=0x1c' \
+  -device 'vmgenid,guid=c773c261-d800-4348-1010-1010add53cf8' \
+  -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' \
+  -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' \
+  -device 'VGA,id=vga,bus=pci.0,addr=0x2' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem0,memdev=mem-virtiomem0,node=0,bus=pci.4,addr=0x4' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem1,memdev=mem-virtiomem1,node=1,bus=pci.4,addr=0x5' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem2,memdev=mem-virtiomem2,node=2,bus=pci.4,addr=0x6' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem3,memdev=mem-virtiomem3,node=3,bus=pci.4,addr=0x7' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem4,memdev=mem-virtiomem4,node=4,bus=pci.4,addr=0x8' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem5,memdev=mem-virtiomem5,node=5,bus=pci.4,addr=0x9' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem6,memdev=mem-virtiomem6,node=6,bus=pci.4,addr=0xa' \
+  -device 'virtio-mem-pci,block-size=4M,requested-size=512M,id=virtiomem7,memdev=mem-virtiomem7,node=7,bus=pci.4,addr=0xb' \
+  -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' \
+  -machine 'type=pc+pve0'
diff --git a/test/cfg2cmd/simple-virtio-mem.conf b/test/cfg2cmd/simple-virtio-mem.conf
new file mode 100644
index 0000000..c9efcde
--- /dev/null
+++ b/test/cfg2cmd/simple-virtio-mem.conf
@@ -0,0 +1,13 @@
+# TEST: Simple test for virtio-mem memory_max
+bootdisk: scsi0
+cores: 2
+memory: 8192
+memory_max: 16384
+name: simple
+numa: 1
+sockets: 1
+ostype: l26
+scsihw: virtio-scsi-pci
+smbios1: uuid=7b10d7af-b932-4c66-b2c3-3996152ec465
+sockets: 1
+vmgenid: c773c261-d800-4348-1010-1010add53cf8
diff --git a/test/cfg2cmd/simple-virtio-mem.conf.cmd b/test/cfg2cmd/simple-virtio-mem.conf.cmd
new file mode 100644
index 0000000..36d6a24
--- /dev/null
+++ b/test/cfg2cmd/simple-virtio-mem.conf.cmd
@@ -0,0 +1,31 @@
+/usr/bin/kvm \
+  -id 8006 \
+  -name 'simple,debug-threads=on' \
+  -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=5' \
+  -mon 'chardev=qmp-event,mode=control' \
+  -pidfile /var/run/qemu-server/8006.pid \
+  -daemonize \
+  -smbios 'type=1,uuid=7b10d7af-b932-4c66-b2c3-3996152ec465' \
+  -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 'size=4096,maxmem=16384M' \
+  -object 'memory-backend-ram,id=ram-node0,size=4096M' \
+  -numa 'node,nodeid=0,cpus=0-1,memdev=ram-node0' \
+  -object 'memory-backend-ram,id=mem-virtiomem0,size=12288M' \
+  -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.0,addr=0x1f' \
+  -device 'pci-bridge,id=pci.4,chassis_nr=4,bus=pci.1,addr=0x1c' \
+  -device 'vmgenid,guid=c773c261-d800-4348-1010-1010add53cf8' \
+  -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' \
+  -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' \
+  -device 'VGA,id=vga,bus=pci.0,addr=0x2' \
+  -device 'virtio-mem-pci,block-size=2M,requested-size=4096M,id=virtiomem0,memdev=mem-virtiomem0,node=0,bus=pci.4,addr=0x4' \
+  -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' \
+  -machine 'type=pc+pve0'
-- 
2.30.2