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Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for h
From: |
Eduardo Habkost |
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 |
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
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Eduardo Habkost, 2020/07/08
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Daniel P . Berrangé, 2020/07/08
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Gerd Hoffmann, 2020/07/09
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Jim Mattson, 2020/07/09
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Eduardo Habkost, 2020/07/09
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Paolo Bonzini, 2020/07/10
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it,
Eduardo Habkost <=
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Paolo Bonzini, 2020/07/10
- Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it, Paolo Bonzini, 2020/07/10