linux-kernel - Re: [PATCH] [v2] x86/sgx: Allow enclaves to use Asynchrounous Exit Notification

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Date:   Fri, 22 Jul 2022 18:44:19 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Kai Huang <kai.huang@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Haitao Huang <haitao.huang@...ux.intel.com>, x86@...nel.org,
        linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] x86/sgx: Allow enclaves to use Asynchrounous Exit
 Notification

On Fri, Jul 22, 2022, Dave Hansen wrote:
> On 7/22/22 06:26, Kai Huang wrote:
> > Did a quick look at the spec.  It appears ENCLU[EDECCSSA] should be used
> > together with AEX-notify.  So besides advertising the new
> > SGX_ATTR_ASYNC_EXIT_NOTIFY bit to the KVM guest, I think we should also
> > advertise the ENCLU[EDECCSSA] support in guest's CPUID, like below (untested)?
> 
> Sounds like a great follow-on patch!  It doesn't seem truly functionally
> required from the spec:
> 
> > EDECCSSA is a new Intel SGX user leaf function
> > (ENCLU[EDECCSSA]) that can facilitate AEX notification handling...

Yeah, it's enumerated separately.

> If that's wrong or imprecise, I'd love to hear more about it and also
> about how the spec will be updated.
> 
> Oh, and the one-liner patch that I was promised for enabling this is
> getting a _wee_ bit longer than one line.

Heh, fool me once...