From: "H. Peter Anvin" <hpa@zytor.com>
To: tytso@mit.edu, Andy Lutomirski <luto@amacapital.net>
Cc: Florian Weimer <fweimer@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kees Cook <kees@outflux.net>, kvm list <kvm@vger.kernel.org>
Subject: Re: random: Providing a seed value to VM guests
Date: Thu, 01 May 2014 12:40:35 -0700 [thread overview]
Message-ID: <068139e3-50f8-4d44-972a-0296b6bc36f7@email.android.com> (raw)
In-Reply-To: <20140501192618.GA25829@thunk.org>
As I said... I think KVM has already added an emulated instructions enumeration API.
On May 1, 2014 12:26:18 PM PDT, tytso@mit.edu wrote:
>On Thu, May 01, 2014 at 12:02:49PM -0700, Andy Lutomirski wrote:
>>
>> Is RDSEED really reasonable here? Won't it slow down by several
>> orders of magnitude?
>
>That is I think the biggest problem; RDRAND and RDSEED are fast if
>they are native, but they will involve a VM exit if they need to be
>emulated. So when an OS might want to use RDRAND and RDSEED might be
>quite different if we know they are being emulated.
>
>Using the RDRAND and RDSEED "api" certainly makes sense, at least for
>x86, but I suspect we might want to use a different way of signalling
>that a VM guest can use RDRAND and RDSEED if they are running on a CPU
>which doesn't provide that kind of access. Maybe a CPUID extended
>function parameter, if one could be allocated for use by a Linux
>hypervisor?
>
> - Ted
--
Sent from my mobile phone. Please pardon brevity and lack of formatting.
next prev parent reply other threads:[~2014-05-01 19:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-01 19:02 Andy Lutomirski
2014-05-01 19:26 ` tytso
2014-05-01 19:40 ` H. Peter Anvin [this message]
2014-05-01 20:16 ` Andy Lutomirski
2014-05-01 20:30 ` H. Peter Anvin
2014-05-01 20:32 ` Andy Lutomirski
2014-05-01 20:39 ` tytso
2014-05-01 20:56 ` Andy Lutomirski
2014-05-01 21:01 ` H. Peter Anvin
2014-05-01 21:06 ` Andy Lutomirski
2014-05-01 22:28 ` tytso
2014-05-01 22:32 ` Andy Lutomirski
2014-05-01 22:46 ` H. Peter Anvin
2014-05-01 22:56 ` Andy Lutomirski
2014-05-01 23:00 ` H. Peter Anvin
2014-05-01 19:41 ` H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2014-04-28 19:52 [PATCH] random: Add "initialized" variable to proc Florian Weimer
2014-04-28 21:41 ` Theodore Ts'o
2014-04-29 17:51 ` Florian Weimer
2014-04-29 18:26 ` Theodore Ts'o
2014-04-30 20:52 ` Andy Lutomirski
2014-05-01 2:06 ` Theodore Ts'o
2014-05-01 4:05 ` H. Peter Anvin
2014-05-01 15:05 ` tytso
2014-05-01 15:35 ` Andy Lutomirski
2014-05-01 18:53 ` Andy Lutomirski
2014-05-01 18:59 ` random: Providing a seed value to VM guests H. Peter Anvin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=068139e3-50f8-4d44-972a-0296b6bc36f7@email.android.com \
--to=hpa@zytor.com \
--cc=fweimer@redhat.com \
--cc=kees@outflux.net \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®