From: Jan Kiszka <jan.kiszka@web.de>
To: "\"李春奇 <Arthur Chunqi Li>\"" <yzt356@gmail.com>
Cc: qemu-devel@nongnu.org, kvm <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] [qemu-devel] Bug Report: VM crashed for some kinds of vCPU in nested virtualization
Date: Tue, 16 Apr 2013 12:29:12 +0200 [thread overview]
Message-ID: <516D27F8.8010707@web.de> (raw)
In-Reply-To: <CABpY8M+PhgWwzcs2ohLhcnG2UDSut48LSBShx8vd4kYM4eKYOw@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 730 bytes --]
On 2013-04-16 12:19, 李春奇 <Arthur Chunqi Li> wrote:
> I looked up Intel manual for VM instruction error. Error number 7 means "VM
> entry with invalid control field(s)", which means in process of VM
> switching some control fields are not properly configured.
>
> I wonder why some emulated CPUs (e.g.Nehalem) can run properly without
> nested VMCS MSR support?
MSRs are only switched between host (L0) and guest (L1/L2) if their
value differ. That saves some cycles. Therefore, if either the guest is
not using a specific MSR (due to differences in the virtual CPU feature
set) or it is using it in the same way like the host, there is no
switching, thus no risk to hit this unimplemented feature.
Jan
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 263 bytes --]
prev parent reply other threads:[~2013-04-16 10:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-15 6:24 [Qemu-devel] [qemu-devel] Bug Report: VM crashed for some kinds of vCPU in nested virtualization 李春奇 <Arthur Chunqi Li>
2013-04-15 7:43 ` Jan Kiszka
2013-04-16 3:49 ` 李春奇 <Arthur Chunqi Li>
2013-04-16 7:03 ` Jan Kiszka
2013-04-16 10:19 ` 李春奇 <Arthur Chunqi Li>
2013-04-16 10:29 ` Jan Kiszka [this message]
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=516D27F8.8010707@web.de \
--to=jan.kiszka@web.de \
--cc=kvm@vger.kernel.org \
--cc=qemu-devel@nongnu.org \
--cc=yzt356@gmail.com \
/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;
as well as URLs for NNTP newsgroup(s).