[pve-devel] [PATCH V2 qemu-server 1/2] enable balloon free-page-reporting

[Alexandre Derumier]

Allow balloon device  driver to report hints of guest free pages to the host,
for auto memory reclaim

https://lwn.net/Articles/759413/
https://events19.linuxfoundation.org/wp-content/uploads/2017/12/KVMForum2018.pdf
Signed-off-by: Alexandre Derumier <aderumier at odiso.com>
---
 PVE/QemuServer.pm | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 42f0fbd..a9e86b3 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -3846,7 +3846,9 @@ sub config_to_command {
     # enable balloon by default, unless explicitly disabled
     if (!defined($conf->{balloon}) || $conf->{balloon}) {
 	my $pciaddr = print_pci_addr("balloon0", $bridges, $arch, $machine_type);
-	push @$devices, '-device', "virtio-balloon-pci,id=balloon0$pciaddr";
+	my $ballooncmd = "virtio-balloon-pci,id=balloon0$pciaddr";
+	$ballooncmd .= ",free-page-reporting=on" if min_version($machine_version, 6, 2);
+	push @$devices, '-device', $ballooncmd;
     }
 
     if ($conf->{watchdog}) {
-- 
2.30.2