[pve-devel] [PATCH v6 qemu-server 04/10] config: memory: add 'max' option

[Alexandre Derumier]

max can be multiple of 64GiB only,
The dimm size is compute from the max memory

we can have 64 slots:

64GiB = 64 slots x 1GiB
128GiB = 64 slots x 2GiB
..
4TiB = 64 slots x 64GiB

Also, with numa, we need to share slot between (up to 8) sockets.

64 is a multiple of 8,

64GiB = 8 sockets * 8 slots * 1GiB
128GiB = 8 sockets * 8 slots * 2GiB
...

and with virtio-mem,
we can have 32000 blocks of 2MiB minimum

64GB = 32000 * 2MiB

Signed-off-by: Alexandre Derumier <aderumier at odiso.com>
---
 PVE/QemuServer.pm        |  4 ++--
 PVE/QemuServer/Memory.pm | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index a751024..1257902 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -5062,7 +5062,7 @@ sub vmconfig_hotplug_pending {
 		vm_deviceunplug($vmid, $conf, $opt);
 		vmconfig_delete_or_detach_drive($vmid, $storecfg, $conf, $opt, $force);
 	    } elsif ($opt =~ m/^memory$/) {
-		die "skip\n" if !$hotplug_features->{memory};
+		die "skip\n" if !PVE::QemuServer::Memory::can_hotplug($hotplug_features->{memory}, $conf);
 		PVE::QemuServer::Memory::qemu_memory_hotplug($vmid, $conf);
 	    } elsif ($opt eq 'cpuunits') {
 		$cgroup->change_cpu_shares(undef);
@@ -5138,7 +5138,7 @@ sub vmconfig_hotplug_pending {
 		vmconfig_update_disk($storecfg, $conf, $hotplug_features->{disk},
 				     $vmid, $opt, $value, $arch, $machine_type);
 	    } elsif ($opt =~ m/^memory$/) { #dimms
-		die "skip\n" if !$hotplug_features->{memory};
+		die "skip\n" if !PVE::QemuServer::Memory::can_hotplug($hotplug_features->{memory}, $conf, $value);
 		$value = PVE::QemuServer::Memory::qemu_memory_hotplug($vmid, $conf, $value);
 	    } elsif ($opt eq 'cpuunits') {
 		my $new_cpuunits = PVE::CGroup::clamp_cpu_shares($conf->{pending}->{$opt}); #clamp
diff --git a/PVE/QemuServer/Memory.pm b/PVE/QemuServer/Memory.pm
index ee73a0a..d25c79c 100644
--- a/PVE/QemuServer/Memory.pm
+++ b/PVE/QemuServer/Memory.pm
@@ -3,8 +3,10 @@ package PVE::QemuServer::Memory;
 use strict;
 use warnings;
 
-use PVE::Tools qw(run_command lock_file lock_file_full file_read_firstline dir_glob_foreach);
 use PVE::Exception qw(raise raise_param_exc);
+use PVE::GuestHelpers qw(safe_num_ne);
+use PVE::JSONSchema;
+use PVE::Tools qw(run_command lock_file lock_file_full file_read_firstline dir_glob_foreach);
 
 use PVE::QemuServer;
 use PVE::QemuServer::Monitor qw(mon_cmd);
@@ -25,8 +27,28 @@ our $memory_fmt = {
 	minimum => 16,
 	default => 512,
     },
+    max => {
+	description => "Maximum hotpluggable memory for the VM in MiB.",
+	type => 'integer',
+	optional => 1,
+	minimum => 65536,
+	maximum => 4194304,
+	format => 'pve-qm-memory-max',
+    },
 };
 
+PVE::JSONSchema::register_format('pve-qm-memory-max', \&verify_qm_memory_max);
+sub verify_qm_memory_max {
+    my ($max, $noerr) = @_;
+
+    if ($max && $max % 65536 != 0) {
+	return undef if $noerr;
+	die "max memory need to be a multiple of 64GiB\n";
+    }
+
+    return $max;
+}
+
 sub print_memory {
     my $memory = shift;
 
@@ -285,6 +307,19 @@ sub qemu_memory_hotplug {
     return $conf->{memory};
 }
 
+sub can_hotplug {
+    my ($hotplug, $conf, $value) = @_;
+
+    return if !$hotplug;
+
+    my $oldmem = parse_memory($conf->{memory});
+    my $newmem = parse_memory($value);
+
+    return if safe_num_ne($newmem->{max}, $oldmem->{max});
+
+    return 1;
+}
+
 sub qemu_memdevices_list {
     my ($vmid, $type) = @_;
 
-- 
2.39.2