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

[Alexandre DERUMIER]

>>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)

I confirm, this break live migration.
(I think you can already add the code for 3.1, like this we'll don't forget it)

----- Mail original -----
De: "Dominik Csapak" <d.csapak at proxmox.com>
À: "pve-devel" <pve-devel at pve.proxmox.com>
Envoyé: Mardi 18 Juin 2019 15:00:50
Objet: Re: [pve-devel] [PATCH qemu-server] fix #2083: Add hv_tlbflush, hv_ipi, hv_evmcs enlightenments

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'; 
> + } 
> } 
> } 
> 
> 


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