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* [PATCH qemu-server] cpu config: Move CPU flags utils to CPUConfig module
@ 2026-02-17 10:50 Arthur Bied-Charreton
  2026-02-17 10:50 ` [PATCH pve-manager] cpu config: Update path to query_supported_cpu_flags Arthur Bied-Charreton
  2026-02-18 10:42 ` [PATCH qemu-server] cpu config: Move CPU flags utils to CPUConfig module Fiona Ebner
  0 siblings, 2 replies; 3+ messages in thread
From: Arthur Bied-Charreton @ 2026-02-17 10:50 UTC (permalink / raw)
  To: pve-devel

...where they fit better alongside other CPU-related utilities.

Signed-off-by: Arthur Bied-Charreton <a.bied-charreton@proxmox.com>
---
 src/PVE/QemuServer.pm           | 131 +-------------------------------
 src/PVE/QemuServer/CPUConfig.pm | 131 +++++++++++++++++++++++++++++++-
 2 files changed, 131 insertions(+), 131 deletions(-)

diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index 5d2dbe03..2121f7c8 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -46,8 +46,7 @@ use PVE::SafeSyslog;
 use PVE::Storage;
 use PVE::SysFSTools;
 use PVE::Systemd;
-use PVE::Tools
-    qw(run_command file_read_firstline file_get_contents dir_glob_foreach get_host_arch $IPV6RE);
+use PVE::Tools qw(run_command file_read_firstline file_get_contents dir_glob_foreach $IPV6RE);
 
 use PVE::QMPClient;
 use PVE::QemuConfig;
@@ -2911,134 +2910,6 @@ sub vga_conf_has_spice {
     return $1 || 1;
 }
 
-# To use query_supported_cpu_flags and query_understood_cpu_flags to get flags
-# to use in a QEMU command line (-cpu element), first array_intersect the result
-# of query_supported_ with query_understood_. This is necessary because:
-#
-# a) query_understood_ returns flags the host cannot use and
-# b) query_supported_ (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.
-#
-# query_supported_ needs to start up to 2 temporary VMs and is therefore rather
-# expensive. If you need the value returned from this, you can get it much
-# cheaper from pmxcfs using PVE::Cluster::get_node_kv('cpuflags-$accel') with
-# $accel being 'kvm' or 'tcg'.
-#
-# pvestatd calls this function on startup and whenever the QEMU/KVM version
-# changes, automatically populating pmxcfs.
-#
-# Returns: { kvm => [ flagX, flagY, ... ], tcg => [ flag1, flag2, ... ] }
-# since kvm and tcg machines support different flags
-#
-sub query_supported_cpu_flags {
-    my ($arch) = @_;
-
-    $arch //= get_host_arch();
-    my $default_machine = PVE::QemuServer::Machine::default_machine_for_arch($arch);
-
-    my $flags = {};
-
-    # FIXME: Once this is merged, the code below should work for ARM as well:
-    # https://lists.nongnu.org/archive/html/qemu-devel/2019-06/msg04947.html
-    die "QEMU/KVM cannot detect CPU flags on ARM (aarch64)\n"
-        if $arch eq "aarch64";
-
-    my $kvm_supported = defined(kvm_version());
-    my $qemu_cmd = PVE::QemuServer::Helpers::get_command_for_arch($arch);
-    my $fakevmid = -1;
-    my $pidfile = PVE::QemuServer::Helpers::vm_pidfile_name($fakevmid);
-
-    # Start a temporary (frozen) VM with vmid -1 to allow sending a QMP command
-    my $query_supported_run_qemu = sub {
-        my ($kvm) = @_;
-
-        my $flags = {};
-        my $cmd = [
-            $qemu_cmd,
-            '-machine',
-            $default_machine,
-            '-display',
-            'none',
-            '-chardev',
-            "socket,id=qmp,path=/var/run/qemu-server/$fakevmid.qmp,server=on,wait=off",
-            '-mon',
-            'chardev=qmp,mode=control',
-            '-pidfile',
-            $pidfile,
-            '-S',
-            '-daemonize',
-        ];
-
-        if (!$kvm) {
-            push @$cmd, '-accel', 'tcg';
-        }
-
-        my $rc = run_command($cmd, noerr => 1, quiet => 0);
-        die "QEMU flag querying VM exited with code " . $rc if $rc;
-
-        eval {
-            my $cmd_result = mon_cmd(
-                $fakevmid,
-                'query-cpu-model-expansion',
-                type => 'full',
-                model => { name => 'host' },
-            );
-
-            my $props = $cmd_result->{model}->{props};
-            foreach my $prop (keys %$props) {
-                next if $props->{$prop} ne '1';
-                # QEMU returns some flags multiple times, with '_', '.' or '-'
-                # (e.g. lahf_lm and lahf-lm; sse4.2, sse4-2 and sse4_2; ...).
-                # We only keep those with underscores, to match /proc/cpuinfo
-                $prop =~ s/\.|-/_/g;
-                $flags->{$prop} = 1;
-            }
-        };
-        my $err = $@;
-
-        # force stop with 10 sec timeout and 'nocheck', always stop, even if QMP failed
-        vm_stop(undef, $fakevmid, 1, 1, 10, 0, 1);
-
-        die $err if $err;
-
-        return [sort keys %$flags];
-    };
-
-    # We need to query QEMU twice, since KVM and TCG have different supported flags
-    PVE::QemuConfig->lock_config(
-        $fakevmid,
-        sub {
-            $flags->{tcg} = eval { $query_supported_run_qemu->(0) };
-            warn "warning: failed querying supported tcg flags: $@\n" if $@;
-
-            if ($kvm_supported) {
-                $flags->{kvm} = eval { $query_supported_run_qemu->(1) };
-                warn "warning: failed querying supported kvm flags: $@\n" if $@;
-            }
-        },
-    );
-
-    return $flags;
-}
-
-# Understood CPU flags are written to a file at 'pve-qemu' compile time
-my $understood_cpu_flag_dir = "/usr/share/kvm";
-
-sub query_understood_cpu_flags {
-    my $arch = get_host_arch();
-    my $filepath = "$understood_cpu_flag_dir/recognized-CPUID-flags-$arch";
-
-    die "Cannot query understood QEMU CPU flags for architecture: $arch (file not found)\n"
-        if !-e $filepath;
-
-    my $raw = file_get_contents($filepath);
-    $raw =~ s/^\s+|\s+$//g;
-    my @flags = split(/\s+/, $raw);
-
-    return \@flags;
-}
-
 # Since commit 277d33454f77ec1d1e0bc04e37621e4dd2424b67 in pve-qemu, smm is not off by default
 # anymore. But smm=off seems to be required when using SeaBIOS and serial display.
 my sub should_disable_smm {
diff --git a/src/PVE/QemuServer/CPUConfig.pm b/src/PVE/QemuServer/CPUConfig.pm
index 32ec4954..e53f0978 100644
--- a/src/PVE/QemuServer/CPUConfig.pm
+++ b/src/PVE/QemuServer/CPUConfig.pm
@@ -9,7 +9,8 @@ use PVE::JSONSchema qw(json_bool);
 use PVE::Cluster qw(cfs_register_file cfs_read_file);
 use PVE::ProcFSTools;
 use PVE::RESTEnvironment qw(log_warn);
-use PVE::Tools qw(run_command);
+use PVE::Tools qw(run_command get_host_arch);
+use PVE::QemuServer::Monitor qw(mon_cmd);
 
 use PVE::QemuServer::Helpers qw(min_version);
 
@@ -579,6 +580,134 @@ sub add_cpu_json_properties {
     return $prop;
 }
 
+# To use query_supported_cpu_flags and query_understood_cpu_flags to get flags
+# to use in a QEMU command line (-cpu element), first array_intersect the result
+# of query_supported_ with query_understood_. This is necessary because:
+#
+# a) query_understood_ returns flags the host cannot use and
+# b) query_supported_ (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.
+#
+# query_supported_ needs to start up to 2 temporary VMs and is therefore rather
+# expensive. If you need the value returned from this, you can get it much
+# cheaper from pmxcfs using PVE::Cluster::get_node_kv('cpuflags-$accel') with
+# $accel being 'kvm' or 'tcg'.
+#
+# pvestatd calls this function on startup and whenever the QEMU/KVM version
+# changes, automatically populating pmxcfs.
+#
+# Returns: { kvm => [ flagX, flagY, ... ], tcg => [ flag1, flag2, ... ] }
+# since kvm and tcg machines support different flags
+#
+sub query_supported_cpu_flags {
+    my ($arch) = @_;
+
+    $arch //= get_host_arch();
+    my $default_machine = PVE::QemuServer::Machine::default_machine_for_arch($arch);
+
+    my $flags = {};
+
+    # FIXME: Once this is merged, the code below should work for ARM as well:
+    # https://lists.nongnu.org/archive/html/qemu-devel/2019-06/msg04947.html
+    die "QEMU/KVM cannot detect CPU flags on ARM (aarch64)\n"
+        if $arch eq "aarch64";
+
+    my $kvm_supported = defined(PVE::QemuServer::kvm_version());
+    my $qemu_cmd = PVE::QemuServer::Helpers::get_command_for_arch($arch);
+    my $fakevmid = -1;
+    my $pidfile = PVE::QemuServer::Helpers::vm_pidfile_name($fakevmid);
+
+    # Start a temporary (frozen) VM with vmid -1 to allow sending a QMP command
+    my $query_supported_run_qemu = sub {
+        my ($kvm) = @_;
+
+        my $flags = {};
+        my $cmd = [
+            $qemu_cmd,
+            '-machine',
+            $default_machine,
+            '-display',
+            'none',
+            '-chardev',
+            "socket,id=qmp,path=/var/run/qemu-server/$fakevmid.qmp,server=on,wait=off",
+            '-mon',
+            'chardev=qmp,mode=control',
+            '-pidfile',
+            $pidfile,
+            '-S',
+            '-daemonize',
+        ];
+
+        if (!$kvm) {
+            push @$cmd, '-accel', 'tcg';
+        }
+
+        my $rc = run_command($cmd, noerr => 1, quiet => 0);
+        die "QEMU flag querying VM exited with code " . $rc if $rc;
+
+        eval {
+            my $cmd_result = mon_cmd(
+                $fakevmid,
+                'query-cpu-model-expansion',
+                type => 'full',
+                model => { name => 'host' },
+            );
+
+            my $props = $cmd_result->{model}->{props};
+            foreach my $prop (keys %$props) {
+                next if $props->{$prop} ne '1';
+                # QEMU returns some flags multiple times, with '_', '.' or '-'
+                # (e.g. lahf_lm and lahf-lm; sse4.2, sse4-2 and sse4_2; ...).
+                # We only keep those with underscores, to match /proc/cpuinfo
+                $prop =~ s/\.|-/_/g;
+                $flags->{$prop} = 1;
+            }
+        };
+        my $err = $@;
+
+        # force stop with 10 sec timeout and 'nocheck', always stop, even if QMP failed
+        PVE::QemuServer::vm_stop(undef, $fakevmid, 1, 1, 10, 0, 1);
+
+        die $err if $err;
+
+        return [sort keys %$flags];
+    };
+
+    # We need to query QEMU twice, since KVM and TCG have different supported flags
+    PVE::QemuConfig->lock_config(
+        $fakevmid,
+        sub {
+            $flags->{tcg} = eval { $query_supported_run_qemu->(0) };
+            warn "warning: failed querying supported tcg flags: $@\n" if $@;
+
+            if ($kvm_supported) {
+                $flags->{kvm} = eval { $query_supported_run_qemu->(1) };
+                warn "warning: failed querying supported kvm flags: $@\n" if $@;
+            }
+        },
+    );
+
+    return $flags;
+}
+
+# Understood CPU flags are written to a file at 'pve-qemu' compile time
+my $understood_cpu_flag_dir = "/usr/share/kvm";
+
+sub query_understood_cpu_flags {
+    my $arch = get_host_arch();
+    my $filepath = "$understood_cpu_flag_dir/recognized-CPUID-flags-$arch";
+
+    die "Cannot query understood QEMU CPU flags for architecture: $arch (file not found)\n"
+        if !-e $filepath;
+
+    my $raw = PVE::Tools::file_get_contents($filepath);
+    $raw =~ s/^\s+|\s+$//g;
+    my @flags = split(/\s+/, $raw);
+
+    return \@flags;
+}
+
 sub get_cpu_models {
     my ($include_custom, $arch) = @_;
 
-- 
2.47.3




^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-02-18 10:41 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-02-17 10:50 [PATCH qemu-server] cpu config: Move CPU flags utils to CPUConfig module Arthur Bied-Charreton
2026-02-17 10:50 ` [PATCH pve-manager] cpu config: Update path to query_supported_cpu_flags Arthur Bied-Charreton
2026-02-18 10:42 ` [PATCH qemu-server] cpu config: Move CPU flags utils to CPUConfig module Fiona Ebner

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