[pve-devel] [PATCH v9 qemu-server 2/6] Include "-cpu" parameter with snapshots/suspend

[Stefan Reiter]

On 06/04/2020 14:31, Fabian Ebner wrote:
> On 26.03.20 16:13, Stefan Reiter wrote:
>> Just like with live-migration, custom CPU models might change after a
>> snapshot has been taken (or a VM suspended), which would lead to a
>> different QEMU invocation on rollback/resume.
>>
>> Save the "-cpu" argument as a new "runningcpu" option into the VM conf
>> akin to "runningmachine" and use as override during rollback/resume.
>>
>> No functional change with non-custom CPU types intended.
>>
> 
> The changes apply to all CPU types, but that's not a bad thing. If one 
> takes a snapshot, restarts the VM with a different CPU type and does a 
> rollback, it'll use the CPU at the time of the snapshot even if no 
> custom models are involved.
> 

Was that a thing before? It should have worked that way anyhow, since 
the 'cpu' setting was stored in the snapshot's section in the config.

>> Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
>> ---
>>   PVE/API2/Qemu.pm  |  1 +
>>   PVE/QemuConfig.pm | 34 ++++++++++++++++++++++++++--------
>>   PVE/QemuServer.pm | 28 ++++++++++++++++++++--------
>>   3 files changed, 47 insertions(+), 16 deletions(-)
>>
>> diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
>> index 80fd7ea..2c7e998 100644
>> --- a/PVE/API2/Qemu.pm
>> +++ b/PVE/API2/Qemu.pm
>> @@ -1129,6 +1129,7 @@ my $update_vm_api  = sub {
>>           push @delete, 'lock'; # this is the real deal to write it out
>>           }
>>           push @delete, 'runningmachine' if $conf->{runningmachine};
>> +        push @delete, 'runningcpu' if $conf->{runningcpu};
>>       }
>>       PVE::QemuConfig->check_lock($conf) if !$skiplock;
>> diff --git a/PVE/QemuConfig.pm b/PVE/QemuConfig.pm
>> index 8d03774..386223d 100644
>> --- a/PVE/QemuConfig.pm
>> +++ b/PVE/QemuConfig.pm
>> @@ -5,6 +5,7 @@ use warnings;
>>   use PVE::AbstractConfig;
>>   use PVE::INotify;
>> +use PVE::QemuServer::CPUConfig;
>>   use PVE::QemuServer::Drive;
>>   use PVE::QemuServer::Helpers;
>>   use PVE::QemuServer::Monitor qw(mon_cmd);
>> @@ -155,15 +156,26 @@ sub __snapshot_save_vmstate {
>>       my $statefile = PVE::Storage::vdisk_alloc($storecfg, $target, 
>> $vmid, 'raw', $name, $size*1024);
>>       my $runningmachine = 
>> PVE::QemuServer::Machine::get_current_qemu_machine($vmid);
>> -    if ($suspend) {
>> -    $conf->{vmstate} = $statefile;
>> -    $conf->{runningmachine} = $runningmachine;
>> -    } else {
>> -    my $snap = $conf->{snapshots}->{$snapname};
>> -    $snap->{vmstate} = $statefile;
>> -    $snap->{runningmachine} = $runningmachine;
>> +    # get current QEMU -cpu argument
>> +    my $runningcpu;
>> +    if (my $pid = PVE::QemuServer::check_running($vmid)) {
>> +    my $cmdline = PVE::QemuServer::Helpers::parse_cmdline($pid);
>> +    die "could not read commandline of running machine\n"
>> +        if !$cmdline->{cpu}->{value};
>> +
>> +    # sanitize and untaint value
>> +    $cmdline->{cpu}->{value} =~ 
>> $PVE::QemuServer::CPUConfig::qemu_cmdline_cpu_re;
>> +    $runningcpu = $1;
>> +    }
>> +
>> +    if (!$suspend) {
>> +    $conf = $conf->{snapshots}->{$snapname};
>>       }
>> +    $conf->{vmstate} = $statefile;
>> +    $conf->{runningmachine} = $runningmachine;
>> +    $conf->{runningcpu} = $runningcpu;
>> +
>>       return $statefile;
>>   }
>> @@ -309,6 +321,11 @@ sub __snapshot_rollback_hook {
>>       if (defined($conf->{runningmachine})) {
>>           $data->{forcemachine} = $conf->{runningmachine};
>>           delete $conf->{runningmachine};
>> +
>> +        # runningcpu is newer than runningmachine, so assume it only 
>> exists
>> +        # here, if at all
>> +        $data->{forcecpu} = delete $conf->{runningcpu}
>> +        if defined($conf->{runningcpu});
>>       } else {
>>           # Note: old code did not store 'machine', so we try to be smart
>>           # and guess the snapshot was generated with kvm 1.4 
>> (pc-i440fx-1.4).
>> @@ -361,7 +378,8 @@ sub __snapshot_rollback_vm_start {
>>       my ($class, $vmid, $vmstate, $data) = @_;
>>       my $storecfg = PVE::Storage::config();
>> -    PVE::QemuServer::vm_start($storecfg, $vmid, $vmstate, undef, 
>> undef, undef, $data->{forcemachine});
>> +    PVE::QemuServer::vm_start($storecfg, $vmid, $vmstate, undef, 
>> undef, undef,
>> +    $data->{forcemachine}, undef, undef, undef, undef, undef, undef, 
>> $data->{forcecpu});
>>   }
>>   sub __snapshot_rollback_get_unused {
>> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
>> index 98c2a9a..70a5234 100644
>> --- a/PVE/QemuServer.pm
>> +++ b/PVE/QemuServer.pm
>> @@ -567,8 +567,15 @@ EODESCR
>>       optional => 1,
>>       }),
>>       runningmachine => get_standard_option('pve-qemu-machine', {
>> -    description => "Specifies the Qemu machine type of the running 
>> vm. This is used internally for snapshots.",
>> +    description => "Specifies the QEMU machine type of the running 
>> vm. This is used internally for snapshots.",
>>       }),
>> +    runningcpu => {
>> +    description => "Specifies the QEMU '-cpu' parameter of the 
>> running vm. This is used internally for snapshots.",
>> +    optional => 1,
>> +    type => 'string',
>> +    pattern => $PVE::QemuServer::CPUConfig::qemu_cmdline_cpu_re,
>> +    format_description => 'QEMU -cpu parameter'
>> +    },
>>       machine => get_standard_option('pve-qemu-machine'),
>>       arch => {
>>       description => "Virtual processor architecture. Defaults to the 
>> host.",
>> @@ -1948,7 +1955,8 @@ sub json_config_properties {
>>       my $prop = shift;
>>       foreach my $opt (keys %$confdesc) {
>> -    next if $opt eq 'parent' || $opt eq 'snaptime' || $opt eq 
>> 'vmstate' || $opt eq 'runningmachine';
>> +    next if $opt eq 'parent' || $opt eq 'snaptime' || $opt eq 
>> 'vmstate' ||
>> +        $opt eq 'runningmachine' || $opt eq 'runningcpu';
>>       $prop->{$opt} = $confdesc->{$opt};
>>       }
>> @@ -4802,8 +4810,9 @@ sub vm_start {
>>       PVE::GuestHelpers::exec_hookscript($conf, $vmid, 'pre-start', 1);
>>       if ($is_suspended) {
>> -        # enforce machine type on suspended vm to ensure HW 
>> compatibility
>> +        # enforce machine type and CPU on suspended vm to ensure HW 
>> compatibility
>>           $forcemachine = $conf->{runningmachine};
>> +        $force_cpu = $conf->{runningcpu};
>>           print "Resuming suspended VM\n";
>>       }
>> @@ -5058,7 +5067,7 @@ sub vm_start {
>>           PVE::Storage::deactivate_volumes($storecfg, [$vmstate]);
>>           PVE::Storage::vdisk_free($storecfg, $vmstate);
>>           }
>> -        delete $conf->@{qw(lock vmstate runningmachine)};
>> +        delete $conf->@{qw(lock vmstate runningmachine runningcpu)};
>>           PVE::QemuConfig->write_config($vmid, $conf);
>>       }
>> @@ -5071,13 +5080,15 @@ sub vm_commandline {
>>       my $conf = PVE::QemuConfig->load_config($vmid);
>>       my $forcemachine;
>> +    my $forcecpu;
>>       if ($snapname) {
>>       my $snapshot = $conf->{snapshots}->{$snapname};
>>       die "snapshot '$snapname' does not exist\n" if !defined($snapshot);
>> -    # check for a 'runningmachine' in snapshot
>> -    $forcemachine = $snapshot->{runningmachine} if 
>> $snapshot->{runningmachine};
>> +    # check for machine or CPU overrides in snapshot
>> +    $forcemachine = $snapshot->{runningmachine};
>> +    $forcecpu = $snapshot->{runningcpu};
>>       $snapshot->{digest} = $conf->{digest}; # keep file digest for API
>> @@ -5086,7 +5097,8 @@ sub vm_commandline {
>>       my $defaults = load_defaults();
>> -    my $cmd = config_to_command($storecfg, $vmid, $conf, $defaults, 
>> $forcemachine);
>> +    my $cmd = config_to_command($storecfg, $vmid, $conf, $defaults,
>> +    $forcemachine, $forcecpu);
>>       return PVE::Tools::cmd2string($cmd);
>>   }
>> @@ -5360,7 +5372,7 @@ sub vm_suspend {
>>               mon_cmd($vmid, "savevm-end");
>>               PVE::Storage::deactivate_volumes($storecfg, [$vmstate]);
>>               PVE::Storage::vdisk_free($storecfg, $vmstate);
>> -            delete $conf->@{qw(vmstate runningmachine)};
>> +            delete $conf->@{qw(vmstate runningmachine runningcpu)};
>>               PVE::QemuConfig->write_config($vmid, $conf);
>>           };
>>           warn $@ if $@;
>>