linux-kernel - Re: [PATCH v25 07/21] x86/sgx: Enumerate and track EPC sections

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Message-ID: <20200206153519.GB9694@linux.intel.com>
Date:   Thu, 6 Feb 2020 17:35:19 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-sgx@...r.kernel.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, nhorman@...hat.com, npmccallum@...hat.com,
        haitao.huang@...el.com, andriy.shevchenko@...ux.intel.com,
        tglx@...utronix.de, kai.svahn@...el.com, bp@...en8.de,
        josh@...htriplett.org, luto@...nel.org, kai.huang@...el.com,
        rientjes@...gle.com, cedric.xing@...el.com, puiterwijk@...hat.com,
        Serge Ayoun <serge.ayoun@...el.com>
Subject: Re: [PATCH v25 07/21] x86/sgx: Enumerate and track EPC sections

On Wed, Feb 05, 2020 at 11:57:00AM -0800, Sean Christopherson wrote:
>   3. Breaks on-demand paging when running in a VM, e.g. if the VMM chooses
>      to allocate a physical EPC page when it's actually accessed by the
>      VM.  I don't expect this to be a problem any time soon, as all VMMs
>      will likely preallocate EPC pages until KVM (or any other hypervisor)
>      gains EPC oversusbscription support, which may or may not ever happen.
>      But, I'd prefer to simply not have the problem in the first place.

So wouldn't it be better to revisit this when the VM changes are added.

/Jarkko