linux-kernel - Re: [PATCH v1 0/4] KVM: MMU: 5 level EPT/shadow support

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Message-ID: <76b17f26-be33-f54d-9023-0fafcf2b2af3@redhat.com>
Date:   Mon, 14 Aug 2017 09:32:44 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yu Zhang <yu.c.zhang@...ux.intel.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rkrcmar@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        xiaoguangrong@...cent.com, joro@...tes.org
Subject: Re: [PATCH v1 0/4] KVM: MMU: 5 level EPT/shadow support

On 12/08/2017 15:35, Yu Zhang wrote:
> Intel's existing processors limit the maximum linear address width to
> 48 bits, and the maximum physical address width to 46 bits. And the
> upcoming processors will extend maximum linear address width to 57 bits
> and maximum physical address width can go upto 52 bits in practical.
> 
> With linear address width greater than 48, a new paging mode in IA-32e
> is introduced - 5 level paging(also known as LA57). And to support VMs
> with this feature, KVM MMU code need to be extended. 
> 
> And to achieve this, this patchset:
> 1> leverages 2 qemu parameters: +la57 and phys-bits to expose wider linear
> address width and physical address width to the VM;
> 2> extends shadow logic to construct 5 level shadow page for VMs running
> in LA57 mode;
> 3> extends ept logic to construct 5 level ept table for VMs whose maximum
> physical width exceeds 48 bits.

Thanks, this looks good.  I only had a few suggestions in my reply to
patch 3.

Paolo