From: Paolo Bonzini <pbonzini@redhat.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Andy Lutomirski <luto@amacapital.net>,
Linux Virtualization <virtualization@lists.linux-foundation.org>
Cc: Mathew John <mathewj@microsoft.com>,
Theodore Ts'o <tytso@mit.edu>,
David Hepkin <davidhep@microsoft.com>,
kvm list <kvm@vger.kernel.org>, Gleb Natapov <gleb@kernel.org>,
Niels Ferguson <niels@microsoft.com>,
Doug Covelli <dcovelli@vmware.com>,
Jim Mattson <jmattson@vmware.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Jake Oshins <jakeo@microsoft.com>,
xen-devel@lists.xenproject.org,
Alok Kataria <akataria@vmware.com>,
John Starks <John.Starks@microsoft.com>
Subject: Re: [Xen-devel] [RFC] Hypervisor RNG and enumeration
Date: Wed, 29 Oct 2014 14:45:41 +0100 [thread overview]
Message-ID: <5450EF85.8090500@redhat.com> (raw)
In-Reply-To: <5450C35D.1030907@citrix.com>
On 10/29/2014 11:37 AM, Andrew Cooper wrote:
> While testing various nested combinations, XenServer has found that
> modern Windows Server versions must have the hypervisor bit hidden from
> them for them to be happy running HyperV, despite the fact that they
> will make use of the Viridian virtual extensions also provided.
Right.
> As a result, while it is certainly advisable for the hypervisor bit to
> be set, CommonHV should be available to be found by paravirtualised
> drivers inside an OS which can't cope with the hypervisor bit set.
Microsoft should just stop putting arbitrary limitations on their
software; or pay the price which, in this case, is not being able to use
the features from the common specification. I guess what they'd do is
reinvent the RNG as a Viridian extension (if they need it).
You can certainly do CPUID(0x4F000000) even if HYPERVISOR=0. What you
get back is undefined, but in all likelihood it won't be the
"CommonHVIntf" string.
Paolo
next prev parent reply other threads:[~2014-10-29 13:45 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-29 5:19 [RFC] Hypervisor RNG and enumeration Andy Lutomirski
2014-10-29 10:37 ` [Xen-devel] " Andrew Cooper
2014-10-29 13:45 ` Paolo Bonzini [this message]
2014-10-29 13:57 ` David Vrabel
2014-10-29 14:01 ` Paolo Bonzini
2014-10-29 16:07 ` H. Peter Anvin
2014-10-29 16:23 ` Andy Lutomirski
2014-10-29 16:07 ` H. Peter Anvin
2014-10-29 16:07 ` H. Peter Anvin
2014-10-29 15:14 ` Ian Jackson
2014-10-29 16:13 ` Andy Lutomirski
2014-10-29 16:29 ` Jake Oshins
2014-10-29 16:50 ` Andy Lutomirski
2014-10-29 18:22 ` Paolo Bonzini
2014-10-30 12:21 ` David Vrabel
2014-10-30 12:25 ` Paolo Bonzini
2014-10-30 14:45 ` Andy Lutomirski
2014-10-30 15:12 ` Ian Campbell
2014-10-30 14:33 ` Roger Pau Monné
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