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fix #2794: allow legacy IGD passthrough

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Legacy IGD passthrough requires address 00:1f.0 to not be assigned to
anything on QEMU startup (currently it's assigned to bridge pci.2).
Changing this in general would break live-migration, so introduce a new
hostpci parameter "legacy-igd", which if set to 1 will move that bridge
to be nested under bridge 1.

This is safe because:
* Bridge 1 is unconditionally created on i440fx, so nesting is ok
* Defaults are not changed, i.e. PCI layout only changes when the new
parameter is specified manually
* hostpci forbids migration anyway

Additionally, the PT device has to be assigned address 00:02.0 in the
guest as well, which is usually used for VGA assignment. Luckily, IGD PT
requires vga=none, so that is not an issue either.

See https://git.qemu.org/?p=qemu.git;a=blob;f=docs/igd-assign.txt

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
This commit is contained in:
Stefan Reiter 2020-06-18 16:36:54 +02:00 committed by Thomas Lamprecht
parent 74c17b7a23
commit 13d689792e
2 changed files with 47 additions and 8 deletions
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10
PVE/QemuServer.pm
View File

@ -3102,7 +3102,7 @@ sub config_to_command {
}
# host pci device passthrough
my ($kvm_off, $gpu_passthrough) = PVE::QemuServer::PCI::print_hostpci_devices(
my ($kvm_off, $gpu_passthrough, $legacy_igd) = PVE::QemuServer::PCI::print_hostpci_devices(
$conf, $devices, $winversion, $q35, $bridges, $arch, $machine_type);
# usb devices
@ -3458,7 +3458,13 @@ sub config_to_command {
for my $k (sort {$b cmp $a} keys %$bridges) {
next if $q35 && $k < 4; # q35.cfg already includes bridges up to 3
$pciaddr = print_pci_addr("pci.$k", undef, $arch, $machine_type);
my $k_name = $k;
if ($k == 2 && $legacy_igd) {
$k_name = "$k-igd";
}
$pciaddr = print_pci_addr("pci.$k_name", undef, $arch, $machine_type);
my $devstr = "pci-bridge,id=pci.$k,chassis_nr=$k$pciaddr";
if ($q35) {
# add after -readconfig pve-q35.cfg

45
PVE/QemuServer/PCI.pm
View File

@ -55,6 +55,14 @@ EODESCR
optional => 1,
default => 0,
},
'legacy-igd' => {
type => 'boolean',
description => "Pass this device in legacy IGD mode (allows required"
. " 1f.0 PCI bridge and assigns correct address)."
. " Requires i440fx machine type and VGA set to 'none'.",
optional => 1,
default => 0,
},
'mdev' => {
type => 'string',
format_description => 'string',
@ -89,7 +97,8 @@ sub get_pci_addr_map {
$pci_addr_map = {
piix3 => { bus => 0, addr => 1, conflict_ok => qw(ehci) },
ehci => { bus => 0, addr => 1, conflict_ok => qw(piix3) }, # instead of piix3 on arm
vga => { bus => 0, addr => 2 },
vga => { bus => 0, addr => 2, conflict_ok => qw(legacy-igd) },
'legacy-igd' => { bus => 0, addr => 2, conflict_ok => qw(vga) }, # legacy-igd requires vga=none
balloon0 => { bus => 0, addr => 3 },
watchdog => { bus => 0, addr => 4 },
scsihw0 => { bus => 0, addr => 5, conflict_ok => qw(pci.3) },
@ -149,6 +158,7 @@ sub get_pci_addr_map {
'xhci' => { bus => 1, addr => 27 },
'pci.4' => { bus => 1, addr => 28 },
'rng0' => { bus => 1, addr => 29 },
'pci.2-igd' => { bus => 1, addr => 30 }, # replaces pci.2 in case a legacy IGD device is passed through
'virtio6' => { bus => 2, addr => 1 },
'virtio7' => { bus => 2, addr => 2 },
'virtio8' => { bus => 2, addr => 3 },
@ -351,6 +361,7 @@ sub print_hostpci_devices {
my $kvm_off = 0;
my $gpu_passthrough = 0;
my $legacy_igd = 0;
for (my $i = 0; $i < $MAX_HOSTPCI_DEVICES; $i++) {
my $id = "hostpci$i";
@ -372,7 +383,32 @@ sub print_hostpci_devices {
$pciaddr = print_pcie_addr($id);
}
} else {
$pciaddr = print_pci_addr($id, $bridges, $arch, $machine_type);
my $pci_name = $d->{'legacy-igd'} ? 'legacy-igd' : $id;
$pciaddr = print_pci_addr($pci_name, $bridges, $arch, $machine_type);
}
my $pcidevices = $d->{pciid};
my $multifunction = 1 if @$pcidevices > 1;
if ($d->{'legacy-igd'}) {
die "only one device can be assigned in legacy-igd mode\n"
if $legacy_igd;
$legacy_igd = 1;
die "legacy IGD assignment requires VGA mode to be 'none'\n"
if !defined($conf->{'vga'}) || $conf->{'vga'} ne 'none';
die "legacy IGD assignment requires rombar to be enabled\n"
if defined($d->{rombar}) && !$d->{rombar};
die "legacy IGD assignment is not compatible with x-vga\n"
if $d->{'x-vga'};
die "legacy IGD assignment is not compatible with mdev\n"
if $d->{mdev};
die "legacy IGD assignment is not compatible with q35\n"
if $q35;
die "legacy IGD assignment is not compatible with multifunction devices\n"
if $multifunction;
die "legacy IGD assignment only works for devices on host bus 00:02.0\n"
if $pcidevices->[0]->{id} !~ m/02\.0$/;
}
my $xvga = '';
@ -383,9 +419,6 @@ sub print_hostpci_devices {
$gpu_passthrough = 1;
}
my $pcidevices = $d->{pciid};
my $multifunction = 1 if @$pcidevices > 1;
my $sysfspath;
if ($d->{mdev} && scalar(@$pcidevices) == 1) {
my $pci_id = $pcidevices->[0]->{id};
@ -420,7 +453,7 @@ sub print_hostpci_devices {
}
}
return ($kvm_off, $gpu_passthrough);
return ($kvm_off, $gpu_passthrough, $legacy_igd);
}
1;