[pve-devel] [PATCH v2 qemu-server 08/12] Rework get_cpu_options and allow custom CPU models

Stefan Reiter s.reiter at proxmox.com
Mon Sep 30 12:58:51 CEST 2019


If the "custom" property on the cpu config is set, try to load the
cputype from the custom CPU model config, and set values accordingly.

While at it, extract currently hardcoded values into seperate sub and add
reasonings.

Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
---

It was quite interesting to dig through old commit messages/mail archives to
find the actual reasons some of our hardcoded flags are included. I do feel like
the "reason" field is quite useful though, both for future developers and users.

 PVE/QemuServer/CPUConfig.pm | 188 ++++++++++++++++++++++++++----------
 1 file changed, 139 insertions(+), 49 deletions(-)

diff --git a/PVE/QemuServer/CPUConfig.pm b/PVE/QemuServer/CPUConfig.pm
index 6f19c2c..e595a69 100644
--- a/PVE/QemuServer/CPUConfig.pm
+++ b/PVE/QemuServer/CPUConfig.pm
@@ -360,96 +360,186 @@ sub print_cpuflag_hash {
 sub get_cpu_options {
     my ($conf, $arch, $kvm, $machine_type, $kvm_off, $kvmver, $winversion, $gpu_passthrough) = @_;
 
-    my $cpuFlags = [];
-    my $ostype = $conf->{ostype};
-
-    my $cpu = $kvm ? "kvm64" : "qemu64";
+    my $cputype = $kvm ? "kvm64" : "qemu64";
     if ($arch eq 'aarch64') {
-	$cpu = 'cortex-a57';
+	$cputype = 'cortex-a57';
     }
-    my $hv_vendor_id;
-    if (my $cputype = $conf->{cpu}) {
-	my $cpuconf = PVE::JSONSchema::parse_property_string($cpu_fmt, $cputype)
-	    or die "Cannot parse cpu description: $cputype\n";
-	$cpu = $cpuconf->{cputype};
-	$kvm_off = 1 if $cpuconf->{hidden};
-	$hv_vendor_id = $cpuconf->{'hv-vendor-id'};
 
-	if (defined(my $flags = $cpuconf->{flags})) {
-	    push @$cpuFlags, split(";", $flags);
+    my $cpuconf = {};
+    my $custom_cpuconf;
+    my $hv_vendor_id;
+    if (my $cpu_prop_str = $conf->{cpu}) {
+	$cpuconf = verify_vm_cpu_conf($cpu_prop_str)
+	    or die "Cannot parse cpu description: $cpu_prop_str\n";
+
+	$cputype = $cpuconf->{cputype};
+	if ($cpuconf->{custom}) {
+	    my $custom_conf = load_custom_model_conf();
+	    $custom_cpuconf = get_model_by_name($custom_conf, $cputype)
+		or die "invalid custom model definition for '$cputype'\n";
+
+	    $cputype = $custom_cpuconf->{'reported-model'};
+	    $kvm_off = $custom_cpuconf->{hidden};
+	    $hv_vendor_id = $custom_cpuconf->{'hv-vendor-id'};
 	}
-    }
-
-    push @$cpuFlags , '+lahf_lm' if $cpu eq 'kvm64' && $arch eq 'x86_64';
 
-    push @$cpuFlags , '-x2apic'
-	if $conf->{ostype} && $conf->{ostype} eq 'solaris';
-
-    push @$cpuFlags, '+sep' if $cpu eq 'kvm64' || $cpu eq 'kvm32';
+	# VM-specific settings override custom CPU config
+	$kvm_off = $cpuconf->{hidden}
+	    if defined($cpuconf->{hidden});
+	$hv_vendor_id = $cpuconf->{'hv-vendor-id'}
+	    if defined($cpuconf->{'hv-vendor-id'});
+    }
 
-    push @$cpuFlags, '-rdtscp' if $cpu =~ m/^Opteron/;
+    my $pve_flags = get_pve_cpu_flags($conf, $kvm, $cputype, $arch,
+				      $machine_type, $kvmver);
 
-    if (qemu_machine_feature_enabled ($machine_type, $kvmver, 2, 3) && $arch eq 'x86_64') {
+    my $hv_flags = get_hyperv_enlightenments($winversion, $machine_type, $kvmver,
+	$conf->{bios}, $gpu_passthrough, $hv_vendor_id) if $kvm;
 
-	push @$cpuFlags , '+kvm_pv_unhalt' if $kvm;
-	push @$cpuFlags , '+kvm_pv_eoi' if $kvm;
+    my $custom_cputype_flags = {};
+    if ($custom_cpuconf && defined($custom_cpuconf->{flags})) {
+	foreach my $flag (split(";", $custom_cpuconf->{flags})) {
+	    $flag =~ m/^([+-])(.*)$/;
+	    $custom_cputype_flags->{$2} = {
+		op => $1,
+		reason => "set by custom CPU model",
+	    }
+	}
     }
 
-    add_hyperv_enlightenments($cpuFlags, $winversion, $machine_type, $kvmver, $conf->{bios}, $gpu_passthrough, $hv_vendor_id) if $kvm;
-
-    push @$cpuFlags, 'enforce' if $cpu ne 'host' && $kvm && $arch eq 'x86_64';
-
-    push @$cpuFlags, 'kvm=off' if $kvm_off;
+    my $vm_flags = {};
+    if (defined(my $flags = $cpuconf->{flags})) {
+	foreach my $flag (split(";", $flags)) {
+	    if ($flag =~ $cpu_flag_re) {
+		$vm_flags->{$2} = {
+		    op => $1,
+		    reason => "manually set for VM",
+		}
+	    }
+	}
+    }
 
-    if (my $cpu_vendor = $cpu_vendor_list->{$cpu}) {
-	push @$cpuFlags, "vendor=${cpu_vendor}"
-	    if $cpu_vendor ne 'default';
+    my $pve_forced_flags = {};
+    $pve_forced_flags->{'enforce'} = {
+	reason => "error if requested CPU settings not available",
+    } if $cputype ne 'host' && $kvm && $arch eq 'x86_64';
+    $pve_forced_flags->{'kvm'} = {
+	value => "off",
+	reason => "hide KVM virtualization from guest",
+    } if $kvm_off;
+
+    # $cputype is the "reported-model" for custom types, so we can just look up
+    # the vendor in the default list
+    my $cpu_vendor = $cpu_vendor_list->{$cputype};
+    if ($cpu_vendor) {
+	$pve_forced_flags->{'vendor'} = {
+	    value => $cpu_vendor,
+	} if $cpu_vendor ne 'default';
     } elsif ($arch ne 'aarch64') {
 	die "internal error"; # should not happen
     }
 
-    $cpu .= "," . join(',', @$cpuFlags) if scalar(@$cpuFlags);
+    my $cpu = $cputype;
+
+    # will be resolved in parameter order
+    $cpu .= resolve_cpu_flags($pve_flags, $hv_flags, $custom_cputype_flags,
+			      $vm_flags, $pve_forced_flags);
 
     return ('-cpu', $cpu);
 }
 
-sub add_hyperv_enlightenments {
-    my ($cpuFlags, $winversion, $machine_type, $kvmver, $bios, $gpu_passthrough, $hv_vendor_id) = @_;
+# Some hardcoded flags required by certain configurations
+sub get_pve_cpu_flags {
+    my ($conf, $kvm, $cputype, $arch, $machine_type, $kvmver) = @_;
+
+    my $pve_flags = {};
+    my $pve_msg = "set by PVE;";
+
+    $pve_flags->{'lahf_lm'} = {
+	op => '+',
+	reason => "$pve_msg to support Windows 8.1+",
+    } if $cputype eq 'kvm64' && $arch eq 'x86_64';
+
+    $pve_flags->{'x2apic'} = {
+	op => '-',
+	reason => "$pve_msg incompatible with Solaris",
+    } if $conf->{ostype} && $conf->{ostype} eq 'solaris';
+
+    $pve_flags->{'sep'} = {
+	op => '+',
+	reason => "$pve_msg to support Windows 8+ and improve Windows XP+",
+    } if $cputype eq 'kvm64' || $cputype eq 'kvm32';
+
+    $pve_flags->{'rdtscp'} = {
+	op => '-',
+	reason => "$pve_msg broken on AMD Opteron",
+    } if $cputype =~ m/^Opteron/;
+
+    if (qemu_machine_feature_enabled ($machine_type, $kvmver, 2, 3)
+	&& $arch eq 'x86_64' && $kvm) {
+	$pve_flags->{'kvm_pv_unhalt'} = {
+	    op => '+',
+	    reason => "$pve_msg improves Linux guest spinlock performance",
+	};
+	$pve_flags->{'kvm_pv_eoi'} = {
+	    op => '+',
+	    reason => "$pve_msg improves Linux guest interrupt performance",
+	};
+    }
+
+    return $pve_flags;
+}
+
+sub get_hyperv_enlightenments {
+    my ($winversion, $machine_type, $kvmver, $bios, $gpu_passthrough, $hv_vendor_id) = @_;
 
     return if $winversion < 6;
     return if $bios && $bios eq 'ovmf' && $winversion < 8;
 
-    if ($gpu_passthrough || defined($hv_vendor_id)) {
+    my $flags = {};
+    my $flagfn = sub {
+	my ($flag, $value, $reason) = @_;
+	$flags->{$flag} = {
+	    reason => $reason // "automatic Hyper-V enlightenment for Windows",
+	    value => $value,
+	}
+    };
+
+    my $hv_vendor_set = defined($hv_vendor_id);
+    if ($gpu_passthrough || $hv_vendor_set) {
 	$hv_vendor_id //= 'proxmox';
-	push @$cpuFlags , "hv_vendor_id=$hv_vendor_id";
+	$flagfn->('hv_vendor_id', $hv_vendor_id, $hv_vendor_set ?
+	    "custom hv_vendor_id set" : "NVIDIA workaround for GPU passthrough");
     }
 
     if (qemu_machine_feature_enabled ($machine_type, $kvmver, 2, 3)) {
-	push @$cpuFlags , 'hv_spinlocks=0x1fff';
-	push @$cpuFlags , 'hv_vapic';
-	push @$cpuFlags , 'hv_time';
+	$flagfn->('hv_spinlocks', '0x1fff');
+	$flagfn->('hv_vapic');
+	$flagfn->('hv_time');
     } else {
-	push @$cpuFlags , 'hv_spinlocks=0xffff';
+	$flagfn->('hv_spinlocks', '0xffff');
     }
 
     if (qemu_machine_feature_enabled ($machine_type, $kvmver, 2, 6)) {
-	push @$cpuFlags , 'hv_reset';
-	push @$cpuFlags , 'hv_vpindex';
-	push @$cpuFlags , 'hv_runtime';
+	$flagfn->('hv_reset');
+	$flagfn->('hv_vpindex');
+	$flagfn->('hv_runtime');
     }
 
     if ($winversion >= 7) {
-	push @$cpuFlags , 'hv_relaxed';
+	$flagfn->('hv_relaxed');
 
 	if (qemu_machine_feature_enabled ($machine_type, $kvmver, 2, 12)) {
-	    push @$cpuFlags , 'hv_synic';
-	    push @$cpuFlags , 'hv_stimer';
+	    $flagfn->('hv_synic');
+	    $flagfn->('hv_stimer');
 	}
 
 	if (qemu_machine_feature_enabled ($machine_type, $kvmver, 3, 1)) {
-	    push @$cpuFlags , 'hv_ipi';
+	    $flagfn->('hv_ipi');
 	}
     }
+
+    return $flags;
 }
 
 sub qemu_machine_feature_enabled {
-- 
2.20.1





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