[pve-devel] [PATCH qemu-server] fix #2083: Add hv_tlbflush, hv_ipi, hv_evmcs enlightenments

[Dominik Csapak]

one comment inline


On 6/18/19 2:20 PM, Stefan Reiter wrote:
> Kernels 4.18+ (4.17+ for evmcs) support new Hyper-V enlightenments for
> Windows KVM guests. QEMU supports these since 3.0.
> tlbflush and ipi improve performance on overcommitted systems, evmcs
> improves nested virtualization.
> 
> It's not entirely clear to me if Win7 already supports these, but since
> they don't cause any penalties, enabling them regardless should be fine.
> 
> Signed-off-by: Stefan Reiter <s.reiter at proxmox.com>
> ---
>   PVE/QemuServer.pm | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 341e0b0..88d07c2 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -7170,6 +7170,13 @@ sub add_hyperv_enlightenments {
>   	    push @$cpuFlags , 'hv_synic';
>   	    push @$cpuFlags , 'hv_stimer';
>   	}
> +
> +	if (qemu_machine_feature_enabled ($machine_type, $kvmver, 3, 0))

since we already rolled out 3.0, i guess this breaks live migration, or 
does this work regardless? (from a machine with older qemu-server, to 
this version)

> +	{
> +	    push @$cpuFlags , 'hv_tlbflush';
> +	    push @$cpuFlags , 'hv_ipi';
> +	    push @$cpuFlags , 'hv_evmcs';
> +	}
>       }
>   }
>   
>