From: "H. Peter Anvin" <hpa@zytor.com>
To: David Hepkin <davidhep@microsoft.com>,
Andy Lutomirski <luto@amacapital.net>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Mathew John <mathewj@microsoft.com>,
Theodore Ts'o <tytso@mit.edu>,
John Starks <John.Starks@microsoft.com>,
kvm list <kvm@vger.kernel.org>, Gleb Natapov <gleb@kernel.org>,
Niels Ferguson <niels@microsoft.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
Jake Oshins <jakeo@microsoft.com>
Subject: Re: Standardizing an MSR or other hypercall to get an RNG seed?
Date: Thu, 18 Sep 2014 14:57:39 -0700 [thread overview]
Message-ID: <541B5553.7020203@zytor.com> (raw)
In-Reply-To: <0180a8dfcad746a895755c4374853c16@BY2PR03MB585.namprd03.prod.outlook.com>
On 09/18/2014 02:46 PM, David Hepkin wrote:
> I'm not sure what you mean by "this mechanism?" Are you suggesting that each hypervisor put "CrossHVPara\0" somewhere in the 0x40000000 - 0x400fffff CPUID range, and an OS has to do a full scan of this CPUID range on boot to find it? That seems pretty inefficient. An OS will take 1000's of hypervisor intercepts on every boot just to search this CPUID range.
>
> I suggest we come to consensus on a specific CPUID leaf where an OS needs to look to determine if a hypervisor supports this capability. We could define a new CPUID leaf range at a well-defined location, or we could just use one of the existing CPUID leaf ranges implemented by an existing hypervisor. I'm not familiar with the KVM CPUID leaf range, but in the case of Hyper-V, the Hyper-V CPUID leaf range was architected to allow for other hypervisors to implement it and just show through specific capabilities supported by the hypervisor. So, we could define a bit in the Hyper-V CPUID leaf range (since Xen and KVM also implement this range), but that would require Linux to look in that range on boot to discover this capability.
>
Yes, I would agree that if anything we should define a new range unique
to this cross-VM interface, e.g. 0x48000000.
-hpa
next prev parent reply other threads:[~2014-09-18 21:57 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-18 2:50 Standardizing an MSR or other hypercall to get an RNG seed? Andy Lutomirski
2014-09-18 14:40 ` KY Srinivasan
2014-09-18 14:43 ` H. Peter Anvin
2014-09-18 15:38 ` Andy Lutomirski
2014-09-18 15:44 ` Andy Lutomirski
2014-09-18 15:58 ` Paolo Bonzini
2014-09-18 16:36 ` KY Srinivasan
2014-09-18 17:13 ` Nakajima, Jun
2014-09-18 17:17 ` Paolo Bonzini
2014-09-18 17:20 ` Jake Oshins
2014-09-18 17:20 ` KY Srinivasan
2014-09-18 17:42 ` Nakajima, Jun
2014-09-18 18:35 ` Andy Lutomirski
2014-09-18 18:39 ` H. Peter Anvin
2014-09-18 18:54 ` Niels Ferguson
2014-09-18 19:03 ` Andy Lutomirski
2014-09-18 21:54 ` David Hepkin
2014-09-19 6:04 ` Paolo Bonzini
2014-09-18 18:58 ` Paolo Bonzini
2014-09-18 19:07 ` Andy Lutomirski
2014-09-18 21:21 ` Nakajima, Jun
2014-09-18 21:35 ` Andy Lutomirski
2014-09-18 21:46 ` David Hepkin
2014-09-18 21:57 ` H. Peter Anvin [this message]
2014-09-18 22:07 ` Andy Lutomirski
2014-09-19 0:49 ` Nakajima, Jun
2014-09-19 1:03 ` Andy Lutomirski
2014-09-19 1:28 ` Andy Lutomirski
2014-09-19 16:14 ` Nakajima, Jun
2014-09-19 16:22 ` Paolo Bonzini
2014-09-19 16:40 ` H. Peter Anvin
2014-09-19 17:21 ` Andy Lutomirski
2014-09-19 17:36 ` H. Peter Anvin
2014-09-19 17:39 ` Andy Lutomirski
2014-09-19 22:05 ` Theodore Ts'o
2014-09-19 22:06 ` Andy Lutomirski
2014-09-19 22:57 ` Nakajima, Jun
2014-09-19 22:57 ` Theodore Ts'o
2014-09-19 23:12 ` Andy Lutomirski
2014-09-19 23:29 ` H. Peter Anvin
2014-09-19 23:29 ` H. Peter Anvin
2014-09-19 23:35 ` Theodore Ts'o
2014-09-19 23:41 ` Andy Lutomirski
2014-09-20 0:06 ` H. Peter Anvin
2014-09-18 22:00 ` Andy Lutomirski
2014-09-18 22:03 ` H. Peter Anvin
2014-09-19 16:37 ` Gleb Natapov
2014-09-19 16:40 ` H. Peter Anvin
2014-09-19 16:53 ` Gleb Natapov
2014-09-19 17:08 ` H. Peter Anvin
2014-09-19 17:15 ` Gleb Natapov
2014-09-19 17:18 ` H. Peter Anvin
2014-09-19 17:18 ` H. Peter Anvin
2014-09-19 17:49 ` Gleb Natapov
2014-09-19 18:02 ` Andy Lutomirski
2014-09-19 18:12 ` Gleb Natapov
2014-09-19 18:20 ` Andy Lutomirski
2014-09-19 20:53 ` Gleb Natapov
2014-09-22 4:11 ` Alok Kataria
2014-09-19 17:21 ` Andy Lutomirski
2014-09-19 17:59 ` Gleb Natapov
2014-09-18 18:56 ` Paolo Bonzini
2014-09-19 18:30 ` Christopher Covington
2014-09-19 18:42 ` Andy Lutomirski
2014-09-19 20:21 ` Nadav Amit
2014-09-19 20:46 ` Andy Lutomirski
2014-09-19 21:46 ` H. Peter Anvin
2014-09-22 13:31 ` Christopher Covington
2014-09-22 14:17 ` H. Peter Anvin
2014-09-22 14:18 ` H. Peter Anvin
2014-09-22 23:01 ` H. Peter Anvin
2014-09-21 12:39 ` Paolo Bonzini
2014-09-22 13:33 ` Christopher Covington
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