linux-kernel - Re: [PATCH 2/2] x86: sgx_vepc: implement SGX_IOC_VEPC

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Message-ID: <88faf121-c731-b99b-13aa-692ccc8c3a98@intel.com>
Date:   Mon, 13 Sep 2021 15:43:41 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, x86@...nel.org, linux-sgx@...r.kernel.org,
        jarkko@...nel.org, dave.hansen@...ux.intel.com,
        yang.zhong@...el.com
Subject: Re: [PATCH 2/2] x86: sgx_vepc: implement SGX_IOC_VEPC_REMOVE ioctl

On 9/13/21 2:11 PM, Sean Christopherson wrote:
> My argument against handling this fully in the kernel is that to handle a vNUMA
> setup with multiple vEPC sections, the ioctl() would need to a take a set of file
> descriptors to handle the case where an SECS is pinned by a child page in a
> diferent vEPC.

Bah, I'm always forgetting about the multiple vepc fd's case.

I completely agree that there's no sane way to do this with a per-vepc
ioctl() when the EREMOVE failures can originate from other vepc instances.

The only other possible thing would be keep an mm_list for vepc
instances and have this ioctl() (or another interface) blast them all.
But that's going to be a heck of a lot more complicated than this is.

OK... you two are wearing me down on this one.

Let's just get this all documented in the changelogs, especially the
retry behavior.