From: Eduardo Habkost <ehabkost@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Jim Mattson" <jmattson@google.com>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
mtosatti@redhat.com,
"Pedro Principeza" <pedro.principeza@canonical.com>,
"kvm list" <kvm@vger.kernel.org>,
libvir-list@redhat.com,
"Dann Frazier" <dann.frazier@canonical.com>,
"Guilherme Piccoli" <gpiccoli@canonical.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Christian Ehrhardt" <christian.ehrhardt@canonical.com>,
qemu-devel@nongnu.org, "Mohammed Gamal" <mgamal@redhat.com>,
"Laszlo Ersek" <lersek@redhat.com>,
fw@gpiccoli.net, rth@twiddle.net
Subject: Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it
Date: Fri, 10 Jul 2020 12:02:19 -0400 [thread overview]
Message-ID: <20200710160219.GQ780932@habkost.net> (raw)
In-Reply-To: <79aa7955-6bc1-d8b2-fed0-48a0990d9dea@redhat.com>
On Fri, Jul 10, 2020 at 09:22:42AM +0200, Paolo Bonzini wrote:
> On 09/07/20 21:13, Eduardo Habkost wrote:
> >> Doesn't this require intercepting MOV-to-CR3 when the guest is in PAE
> >> mode, so that the hypervisor can validate the high bits in the PDPTEs?
> > If the fix has additional overhead, is the additional overhead
> > bad enough to warrant making it optional? Most existing
> > GUEST_MAXPHYADDR < HOST_MAXPHYADDR guests already work today
> > without the fix.
>
> The problematic case is when host maxphyaddr is 52. That case wouldn't
> work at all without the fix.
What can QEMU do to do differentiate "can't work at all without
the fix" from "not the best idea, but will probably work"?
--
Eduardo
next prev parent reply other threads:[~2020-07-10 16:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 15:53 [PATCH 0/2] kvm: x86/cpu: Support guest MAXPHYADDR < host MAXPHYADDR Mohammed Gamal
2020-06-19 15:53 ` [PATCH 1/2] kvm: Add support for KVM_CAP_HAS_SMALLER_MAXPHYADDR Mohammed Gamal
2020-06-19 15:53 ` [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it Mohammed Gamal
2020-06-19 16:25 ` Paolo Bonzini
2020-07-08 17:16 ` Eduardo Habkost
2020-07-08 17:26 ` Daniel P. Berrangé
2020-07-09 9:44 ` Gerd Hoffmann
2020-07-09 9:55 ` Mohammed Gamal
2020-07-09 10:11 ` Paolo Bonzini
2020-07-09 17:00 ` Jim Mattson
2020-07-09 19:13 ` Eduardo Habkost
2020-07-10 7:22 ` Paolo Bonzini
2020-07-10 16:02 ` Eduardo Habkost [this message]
2020-07-10 16:49 ` Paolo Bonzini
2020-07-10 7:21 ` Paolo Bonzini
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=20200710160219.GQ780932@habkost.net \
--to=ehabkost@redhat.com \
--cc=berrange@redhat.com \
--cc=christian.ehrhardt@canonical.com \
--cc=dann.frazier@canonical.com \
--cc=dgilbert@redhat.com \
--cc=fw@gpiccoli.net \
--cc=gpiccoli@canonical.com \
--cc=jmattson@google.com \
--cc=kraxel@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=lersek@redhat.com \
--cc=libvir-list@redhat.com \
--cc=mgamal@redhat.com \
--cc=mtosatti@redhat.com \
--cc=pbonzini@redhat.com \
--cc=pedro.principeza@canonical.com \
--cc=qemu-devel@nongnu.org \
--cc=rth@twiddle.net \
/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