[pve-devel] [PATCH qemu-server 5/7] Support custom CPU types in get_cpu_options

[Fabian Grünbichler]

On September 2, 2019 4:27 pm, Stefan Reiter wrote:
> Supports custom basemodels (model shown to QEMU, i.e. must be a default

nit: s/shown/known/ ?

high-level: if we allow basing custom models on other custom models, 
wouldn't we need to compute an effective model first, and then use that?

e.g., if I define the following:

cpu-model: leaf
  basemodel: intermediate
  vendor: intel
  flags: +aes,+pcid
  host-phys-bits: 1

cpu-model: intermediate1
  vendor: amd
  basemodel: intermediate2
  flags: -aes;-ssbd
  phys-bits: 32

cpu-model: intermediate2
  vendor: amd
  basemodel: phenom
  flags: +ssbd;+md-clear
  phys-bits: 48

I'd expect the end result to be:

vendor: intel
flags: phenom +aes +pcid -ssbd +md-clear
phys-bits: host (overriding the one from intermediate)

(ignore that those flags don't make much sense ;))

this patch (series) only looks at the leaf and the last basemodel in the 
chain, and ignores everything inbetween. vendor also can't be 
'inherited' from basemodel, because it is always set.

we can either go full-blown 'inherit properties across multiple 
basemodels', or we limit ourselves to 'basemodel must be a regular cpu 
model'. the former is of course more flexible (allowing stuff like 
re-using a custom model and just adding one flag, without duplication), 
but the latter is a lot more simple (one additional level to check 
instead of recursive walk, loop and conflict detection, no nested 
versioning needed, etc.pp.). something inbetween like the current patch 
does is probably confusing.

> model), vendors and (host-)phys-bits for VMs with large amounts of RAM
> (see bug #2318).
> 
> Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
> ---
>  PVE/QemuServer.pm | 32 +++++++++++++++++++++++++++++++-
>  1 file changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 97fa955..417bea8 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -37,6 +37,7 @@ use PVE::QemuServer::PCI qw(print_pci_addr print_pcie_addr);
>  use PVE::QemuServer::Memory;
>  use PVE::QemuServer::USB qw(parse_usb_device);
>  use PVE::QemuServer::Cloudinit;
> +use PVE::QemuServer::CustomCPUConfig;
>  use PVE::SysFSTools;
>  use PVE::Systemd;
>  use Time::HiRes qw(gettimeofday);
> @@ -3595,10 +3596,30 @@ sub get_cpu_options {
>  	$cpu = 'cortex-a57';
>      }
>      my $hv_vendor_id;
> +    my $custom_cpu_config;
>      if (my $cputype = $conf->{cpu}) {
>  	my $cpuconf = PVE::JSONSchema::parse_property_string($cpu_fmt, $cputype)
>  	    or die "Cannot parse cpu description: $cputype\n";
>  	$cpu = $cpuconf->{cputype};
> +
> +	if (!defined($cpu_vendor_list->{$cpu})) {
> +	    # not a default CPU model, read config and see if $cpu is name of
> +	    # a custom model
> +	    my $cpu_models = PVE::QemuServer::CustomCPUConfig::config_from_file();
> +	    if ($cpu_models && ($custom_cpu_config = $cpu_models->get_model_by_name($cpu))) {
> +		$cpu = $custom_cpu_config->{basemodel};
> +
> +		# 'basemodel' could be custom as well
> +		while (!defined($cpu_vendor_list->{$cpu})) {
> +		    my $custom_base = $cpu_models->get_model_by_name($cpu);
> +		    die "unknown CPU basemodel: $cpu\n" if !$custom_base;
> +		    $cpu = $custom_base->{basemodel};
> +		}

possible endless loop

> +	    } else {
> +		die "unknown CPU model (neither default nor custom): $cpu\n";
> +	    }
> +	}
> +
>  	$kvm_off = 1 if $cpuconf->{hidden};
>  	$hv_vendor_id = $cpuconf->{'hv-vendor-id'};
>  
> @@ -3628,13 +3649,22 @@ sub get_cpu_options {
>  
>      push @$cpuFlags, 'kvm=off' if $kvm_off;
>  
> -    if (my $cpu_vendor = $cpu_vendor_list->{$cpu}) {
> +    if (defined($custom_cpu_config) && (my $custom_vendor = $custom_cpu_config->{vendor})) {
> +	push @$cpuFlags, "vendor=${custom_vendor}"
> +	    if $custom_vendor ne 'default';
> +    } elsif (my $cpu_vendor = $cpu_vendor_list->{$cpu}) {
>  	push @$cpuFlags, "vendor=${cpu_vendor}"
>  	    if $cpu_vendor ne 'default';
>      } elsif ($arch ne 'aarch64') {
>  	die "internal error"; # should not happen
>      }
>  
> +    $cpu .= ",host-phys-bits=true"
> +	if defined($custom_cpu_config) && $custom_cpu_config->{'host-phys-bits'};
> +    $cpu .= ",phys-bits=$custom_cpu_config->{'phys-bits'}"
> +	if defined($custom_cpu_config) && $custom_cpu_config->{'phys-bits'}
> +	&& !$custom_cpu_config->{'host-phys-bits'};
> +
>      $cpu .= "," . join(',', @$cpuFlags) if scalar(@$cpuFlags);
>  
>      return ('-cpu', $cpu);
> -- 
> 2.20.1
> 
> 
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