linux-kernel - Re: [PATCH 1/5] KVM: nVMX: Make nested control MSRs per-cpu.

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Message-ID: <CACzj_yW056JWb_+SbdQpfRfqJEUoWk4bRmGjnDOm18UgEzHwYA@mail.gmail.com>
Date:	Wed, 21 Jan 2015 17:23:44 +0800
From:	Wincy Van <fanwenyi0529@...il.com>
To:	"Zhang, Yang Z" <yang.z.zhang@...el.com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	"gleb@...nel.org" <gleb@...nel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Jan Kiszka <jan.kiszka@....de>
Subject: Re: [PATCH 1/5] KVM: nVMX: Make nested control MSRs per-cpu.

On Wed, Jan 21, 2015 at 4:18 PM, Zhang, Yang Z <yang.z.zhang@...el.com> wrote:
> Wincy Van wrote on 2015-01-16:
>> To enable nested apicv support, we need per-cpu vmx control MSRs:
>>   1. If in-kernel irqchip is enabled, we can enable nested
>>      posted interrupt, we should set posted intr bit in the
>>      nested_vmx_pinbased_ctls_high. 2. If in-kernel irqchip is disabled,
>>      we can not enable nested posted interrupt, the posted intr bit in
>>      the nested_vmx_pinbased_ctls_high will be cleared.
>> Since there would be different settings about in-kernel irqchip
>> between VMs, different nested control MSRs are needed.
>
> I'd suggest you to check irqchip_in_kernel() instead moving the whole ctrl msr to per vcpu.
>

Yes, moving that msrs looks a bit ugly, but the irqchip_in_kernel is
per-VM, not a global
setting, there would be different settings of kernel_irqchip between VMs.
If we use irqchip_in_kernel to check it and set different value of the
ctl msrs, I think it may
be even worse than moving the msrs, because this logic should be a
init function, and this
setting should be converged.

Thanks,

Wincy
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