Will implement all of this for v2, just a note inline.
On 9/6/19 1:42 PM, Fabian Grünbichler wrote:
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 :-/
Yes, this is for exposing via the API (for the GUI to create/edit custom
models I have in mind). I just thought it fits with this patch well,
since the comments refer to each other.
Also, query_understood_cpu_flags returns 188 flags for me, while
query_supported_cpu_flags only returns 104...
The discrepancies generally arise because
a) query_understood_cpu_flags returns flags the host cannot use and
b) query_supported_cpu_flags (rather the QMP call) doesn't actually
return CPU flags, but CPU settings - with most of them being flags.
Those settings (and some flags, curiously) cannot be specified as a
"-cpu" argument however.
The intersection of those provides only flags that can be passed to
"-cpu" without issues in my testing. Since query_understood_cpu_flags is
not host specific though, it doesn't need broadcasting.
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
I'll try to make the comments/message more informative.
+ 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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