linux-kernel - Re: SEV guest regression in 4.18

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Date:   Thu, 23 Aug 2018 13:26:55 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Brijesh Singh <brijesh.singh@....com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Borislav Petkov <bp@...e.de>
Cc:     "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: SEV guest regression in 4.18

On 22/08/2018 22:11, Brijesh Singh wrote:
> 
> Yes, this is one of approach I have in mind. It will avoid splitting
> the larger pages; I am thinking that early in boot code we can lookup
> for this special section and decrypt it in-place and probably maps with
> C=0. Only downside, it will increase data section footprint a bit
> because we need to align this section to PM_SIZE.

If you can ensure it doesn't span a PMD, maybe it does not need to be
aligned; you could establish a C=0 mapping of the whole 2M around it.

Paolo