On September 2, 2019 4:27 pm, Stefan Reiter wrote:
> * query_understood_cpu_flags returns all flags that QEMU/KVM knows about
> * query_supported_cpu_flags returns all flags that QEMU/KVM can use on
> this particular host.
>
> To get supported flags, a temporary VM is started with QEMU, so we can
> issue the "query-cpu-model-expansion" QMP command. This is how libvirt
> queries supported flags for its "host-passthrough" CPU type.
>
> query_supported_cpu_flags is thus rather slow and shouldn't be called
> unnecessarily.
>
> Signed-off-by: Stefan Reiter <s.rei...@proxmox.com>
> ---
>
> Changes from RFC:
>
> * Clearer regexes
> * Use existing QMP infrastructure
> * Add locking for temporary VM start
> * Add comments
>
>
> PVE/QemuServer.pm | 84 +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 84 insertions(+)
>
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 8c519b5..97fa955 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -3500,6 +3500,90 @@ sub get_command_for_arch($) {
> return $cmd;
> }
>
> +# The format of the flags returned here uses dashes '-' as seperators,
nit: s/seperator/separator/a
> +# this is neither the default for 'query_supported_cpu_flags' below, nor for
> +# /proc/cpuinfo.
> +#
> +# To compare (or array_intersect) flags, it's a good idea to convert them all
> +# to a common format first (e.g. map s/\.|-/_/g).
> +sub query_understood_cpu_flags {
not used anywhere in this series? also, confusingly, this returns less
values then the other helper (maybe because of some aliases?), and it's
not a strict subset :-/
I guess this is in preparation of exposing it via the API? some sort of
comment how _understood and _supported interact/are supposed to interact
would be nice. either as comment or part of the commit message
> + my $flags = [];
> + my $flag_section = 0;
> +
> + run_command(
> + [get_command_for_arch('x86_64'), '-cpu', 'help'],
why not get_host_arch()?
> + noerr => 1,
> + quiet => 1,
> + outfunc => sub {
> + my ($line) = @_;
> +
> + if ($flag_section) {
> + return if $line =~ m/^\s*$/;
> + $line =~ s/^\s*|\s*$//g;
> + push @$flags, split(/\s+/, $line);
> + } elsif ($line =~ m/^\s*Recognized CPUID flags:\s*$/) {
> + $flag_section = 1;
> + }
> + }
> + );
> +
> + return $flags;
> +}
> +
> +# This function needs to start a temporary VM and is therefore rather
> expensive.
> +# If you need the value returned from this, you can get it much cheaper from
> +# pvestatd using PVE::Cluster::get_node_kv('cpuflags').
s/pvestatd/pmxcfs/
pvestatd is just the one putting it there ;)
> +#
> +# See also note to query_understood_cpu_flags above.
> +sub query_supported_cpu_flags {
> + my $flags = [];
> +
> + my $vmid = -1;
> + my $pidfile = pidfile_name($vmid);
> +
> + PVE::QemuConfig->lock_config($vmid, sub {
> + # We start a temporary (frozen) VM with vmid -1 to allow us to send a
> QMP command
> + my $rc = run_command([
> + get_command_for_arch('x86_64'),
again, why not get_host_arch()?
> + '-cpu', 'kvm64',
> + '-display', 'none',
> + '-chardev',
> "socket,id=qmp,path=/var/run/qemu-server/$vmid.qmp,server,nowait",
> + '-mon', 'chardev=qmp,mode=control',
> + '-pidfile', $pidfile,
> + '-S', '-daemonize'
> + ], noerr => 1, quiet => 1);
> + return if $rc;
> +
> + my $cmd_result = vm_mon_cmd_nocheck(
> + $vmid,
> + 'query-cpu-model-expansion',
> + type => 'full',
> + model => { name => 'host' }
> + );
> +
> + my $props = $cmd_result->{model}->{props};
> + if (%$props) {
> + foreach my $prop (keys %$props) {
> + push @$flags, $prop if "$props->{$prop}" eq '1';
> + }
> + }
> +
> + # force stop with 10 sec timeout and 'nocheck'
> + vm_stop(undef, $vmid, 1, 1, 10, 0, 1);
> + });
> +
> + # QEMU returns some flags multiple times, with '_', '.' or '-' as
> seperator
> + # (e.g. lahf_lm and lahf-lm; sse4.2, sse4-2 and sse4_2; ...).
> + # We only keep those with underscores, since they match the ones from
> + # /proc/cpuinfo (they do the same thing, but we get rid of duplicates).
> + @$flags = grep {
> + my $replaced = (my $underscore = $_) =~ s/\.|-/_/g;
> + !($replaced && grep { $_ eq $underscore } @$flags)
> + } @$flags;
> +
> + return $flags;
> +}
> +
> sub get_cpu_options {
> my ($conf, $arch, $kvm, $machine_type, $kvm_off, $kvmver, $winversion,
> $gpu_passthrough) = @_;
>
> --
> 2.20.1
>
>
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