linux-kernel - RE: [PATCH 4/4] x86: properly handle kvm emulation of hyperv

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Date:	Tue, 23 Jul 2013 13:55:17 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Jason Wang <jasowang@...hat.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>, "x86@...nel.org" <x86@...nel.org>,
	"gleb@...hat.com" <gleb@...hat.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 4/4] x86: properly handle kvm emulation of hyperv



> -----Original Message-----
> From: Jason Wang [mailto:jasowang@...hat.com]
> Sent: Tuesday, July 23, 2013 5:41 AM
> To: tglx@...utronix.de; mingo@...hat.com; hpa@...or.com; x86@...nel.org;
> gleb@...hat.com; pbonzini@...hat.com; kvm@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Cc: Jason Wang; KY Srinivasan
> Subject: [PATCH 4/4] x86: properly handle kvm emulation of hyperv
> 
> Recent kvm has some basic support of hyperv, this will cause the guest to
> identify itself as running on top of hyperv instead of kvm which will disable
> kvm pv functionality. This is because we try to detect hyperv before kvm. Solve
> this by simply checking kvm in detect_hypervisor() first.
> 

This strategy of hypervisor detection based on some detection order IMHO is not
a robust detection strategy. The current scheme works since the only hypervisor emulated
(by other hypervisors happens to be Hyper-V). What if this were to change.

Regards,

K. Y



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