[libvirt] [PATCH 2/2] Also filter out non-migratable features out of host-passthrough

[John Ferlan]

On 09/29/2014 10:27 AM, Ján Tomko wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1147584

Could this be expanded a bit - so one doesn't have to chase into the bz
in order to understand what is/was being fixed?

> ---
>  src/cpu/cpu_x86.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c
> index a98a847..57f343c 100644
> --- a/src/cpu/cpu_x86.c
> +++ b/src/cpu/cpu_x86.c
> @@ -2068,7 +2068,8 @@ x86UpdateCustom(virCPUDefPtr guest,
>  
>  static int
>  x86UpdateHostModel(virCPUDefPtr guest,
> -                   const virCPUDef *host)
> +                   const virCPUDef *host,
> +                   bool passthrough)
>  {
>      virCPUDefPtr oldguest = NULL;
>      const struct x86_map *map;
> @@ -2076,8 +2077,6 @@ x86UpdateHostModel(virCPUDefPtr guest,
>      size_t i;
>      int ret = -1;
>  
> -    guest->match = VIR_CPU_MATCH_EXACT;
> -
>      if (!(map = virCPUx86GetMap()))
>          goto cleanup;
>  
> @@ -2100,8 +2099,7 @@ x86UpdateHostModel(virCPUDefPtr guest,
>              }
>          }
>      }

So if I understand correctly the above loop removes not migrate-able
features - from the passed in migrated cpu and the loop below is
updating features for anything left.

So given my question from patch 1/2 - it seems if features weren't
allowed for host-passthrough, well then neither of these would be
necessary.

In any case - even if we added something that removed features, the
incoming, saved/restore, etc. guest with host-passthrough could still
have it so this would be necessary - which I guess means it's an ACK
(typing and thinking).

John
> -
> -    for (i = 0; i < oldguest->nfeatures; i++) {
> +    for (i = 0; !passthrough && i < oldguest->nfeatures; i++) {
>          if (virCPUDefUpdateFeature(guest,
>                                     oldguest->features[i].name,
>                                     oldguest->features[i].policy) < 0)
> @@ -2125,12 +2123,12 @@ x86Update(virCPUDefPtr guest,
>          return x86UpdateCustom(guest, host);
>  
>      case VIR_CPU_MODE_HOST_MODEL:
> -        return x86UpdateHostModel(guest, host);
> +        guest->match = VIR_CPU_MATCH_EXACT;
> +        return x86UpdateHostModel(guest, host, false);
>  
>      case VIR_CPU_MODE_HOST_PASSTHROUGH:
>          guest->match = VIR_CPU_MATCH_MINIMUM;
> -        virCPUDefFreeModel(guest);
> -        return virCPUDefCopyModel(guest, host, true);
> +        return x86UpdateHostModel(guest, host, true);
>  
>      case VIR_CPU_MODE_LAST:
>          break;
>