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Re: Questions about the real mode in kvm/qemu
From: |
Paolo Bonzini |
Subject: |
Re: Questions about the real mode in kvm/qemu |
Date: |
Thu, 26 Sep 2019 11:18:30 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 26/09/19 10:59, Maxim Levitsky wrote:
> If you mean to ask if there is a way to let guest access use no
> paging at all, that is access host physical addresses directly, then
> indeed there is no way, since regular non 'unrestricted guest' mode
> required both protected mode and paging, and 'unrestricted guest'
> requires EPT. Academically speaking it is of course possible to
> create paging tables that are 1:1...
Not so academically, it's exactly what KVM does. However, indeed it
would also be possible to switch out of EPT mode when CR0.PG=0. I'm not
sure why it was done this way, maybe when the code was written it was
simpler to use the identity map.
Let's see if Avi is listening... :)
Paolo
- Questions about the real mode in kvm/qemu, Li Qiang, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Maxim Levitsky, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Li Qiang, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Maxim Levitsky, 2019/09/26
- Re: Questions about the real mode in kvm/qemu,
Paolo Bonzini <=
- Re: Questions about the real mode in kvm/qemu, Maxim Levitsky, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Paolo Bonzini, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Maxim Levitsky, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Paolo Bonzini, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Maxim Levitsky, 2019/09/26
- Re: Questions about the real mode in kvm/qemu, Avi Kivity, 2019/09/28
- Re: Questions about the real mode in kvm/qemu, Li Qiang, 2019/09/29
Re: Questions about the real mode in kvm/qemu, Paolo Bonzini, 2019/09/26