[pve-devel] [PATCH qemu-server v2 1/2] pci: add helpers to (un)reserve pciids for a vm

[Dominik Csapak]

saves a list of pciid <-> vmid mappings in /var/run
that we can check when we start a vm

if we're not given a pid but a timeout, we save the time when the
reservation will run out (current time + timeout + 5s) since each
vm start (until we can save the pid) varies from config to config

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
 PVE/QemuServer/PCI.pm | 99 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/PVE/QemuServer/PCI.pm b/PVE/QemuServer/PCI.pm
index 5608207..364ceb7 100644
--- a/PVE/QemuServer/PCI.pm
+++ b/PVE/QemuServer/PCI.pm
@@ -5,6 +5,7 @@ use strict;
 
 use PVE::JSONSchema;
 use PVE::SysFSTools;
+use PVE::Tools;
 
 use base 'Exporter';
 
@@ -461,4 +462,102 @@ sub print_hostpci_devices {
     return ($kvm_off, $gpu_passthrough, $legacy_igd);
 }
 
+my $PCIID_RESERVATION_FILE = "/var/run/pve-reserved-pciids";
+my $PCIID_RESERVATION_LCK = "/var/lock/pve-reserved-pciids.lck";
+
+my $parse_pci_reservation = sub {
+    my $pciids = {};
+
+    if (my $fh = IO::File->new ($PCIID_RESERVATION_FILE, "r")) {
+	while (my $line = <$fh>) {
+	    if ($line =~ m/^($PCIRE)\s(\d+)\stime\:(\d+)$/) {
+		$pciids->{$1} = {
+		    vmid => $2,
+		    timestamp => $3,
+		};
+	    } elsif ($line =~ m/^($PCIRE)\s(\d+)\spid\:(\d+)$/s) {
+		$pciids->{$1} = {
+		    vmid => $2,
+		    pid => $3,
+		};
+	    }
+	}
+    }
+
+    return $pciids;
+};
+
+my $write_pci_reservation = sub {
+    my ($pciids) = @_;
+
+    my $data = "";
+    foreach my $p (keys %$pciids) {
+	my $entry = $pciids->{$p};
+	if (defined($entry->{pid})) {
+	    $data .= "$p $entry->{vmid} pid:$entry->{pid}\n";
+	} else {
+	    $data .= "$p $entry->{vmid} time:$entry->{timestamp}\n";
+	}
+    }
+
+    PVE::Tools::file_set_contents($PCIID_RESERVATION_FILE, $data);
+};
+
+sub remove_pci_reservation {
+    my ($id) = @_;
+
+    my $code = sub {
+	my $pciids = $parse_pci_reservation->();
+
+	delete $pciids->{$id};
+
+	$write_pci_reservation->($pciids);
+    };
+
+    PVE::Tools::lock_file($PCIID_RESERVATION_LCK, 10, $code);
+    die $@ if $@;
+
+    return;
+}
+
+sub reserve_pci_usage {
+    my ($id, $vmid, $timeout, $pid) = @_;
+
+    PVE::Tools::lock_file($PCIID_RESERVATION_LCK, 10, sub {
+
+	my $ctime = time();
+	my $errmsg = "PCI device '$id' already in use\n";
+
+	my $pciids = $parse_pci_reservation->();
+
+	if (my $pciid = $pciids->{$id}) {
+	    if ($pciid->{vmid} != $vmid) {
+		# check time based reservation
+		die $errmsg if defined($pciid->{timestamp}) && $pciid->{timestamp} > $ctime;
+
+		# check running vm
+		my $pid = PVE::QemuServer::Helpers::vm_running_locally($pciid->{vmid});
+		die $errmsg if defined($pciid->{pid}) && $pid == $pciid->{pid};
+	    }
+	}
+
+	$pciids->{$id} = {
+	    vmid => $vmid,
+	};
+	if (defined($timeout)) {
+	    # we save the timestamp when the reservation gets invalid (+5s),
+	    # since the start timeout depends on the config
+	    $pciids->{$id}->{timestamp} = $ctime + $timeout + 5;
+	}
+	$pciids->{$id}->{pid} = $pid if defined($pid);
+
+	$write_pci_reservation->($pciids);
+
+	return;
+    });
+    die $@ if $@;
+
+    return;
+}
+
 1;
-- 
2.30.2