linux-kernel - Re: [PATCH v5 09/18] x86/sgx: Store struct sgx

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Message-ID: <op.2b1f8j1bwjvjmi@hhuan26-mobl.amr.corp.intel.com>
Date:   Fri, 29 Sep 2023 10:06:09 -0500
From:   "Haitao Huang" <haitao.huang@...ux.intel.com>
To:     "mingo@...hat.com" <mingo@...hat.com>,
        "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "tj@...nel.org" <tj@...nel.org>,
        "Mehta, Sohil" <sohil.mehta@...el.com>,
        "Huang, Kai" <kai.huang@...el.com>
Cc:     "kristen@...ux.intel.com" <kristen@...ux.intel.com>,
        "anakrish@...rosoft.com" <anakrish@...rosoft.com>,
        "Li, Zhiquan1" <zhiquan1.li@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "mikko.ylinen@...ux.intel.com" <mikko.ylinen@...ux.intel.com>,
        "yangjie@...rosoft.com" <yangjie@...rosoft.com>,
        "Zhang, Bo" <zhanb@...rosoft.com>
Subject: Re: [PATCH v5 09/18] x86/sgx: Store struct sgx_encl when allocating
 new VA pages

On Wed, 27 Sep 2023 16:21:19 -0500, Huang, Kai <kai.huang@...el.com> wrote:

> On Wed, 2023-09-27 at 10:35 -0500, Haitao Huang wrote:
>> > > +
>> > > +	/* Possible owner types */
>> > > +	union {
>> > > +		struct sgx_encl_page *encl_page;
>> > > +		struct sgx_encl *encl;
>> > > +	};
>> >
>> > Sadly for virtual EPC page the owner is set to the 'sgx_vepc'  
>> instance it
>> > belongs to.
>> >
>> > Given how sgx_{alloc|free}_epc_page() arbitrarily uses encl_page,>  
>> perhaps we
>> > should do below?
>> >
>> >  	union {
>> >  		struct sgx_encl_page *encl_page;
>> >  		struct sgx_encl *encl;
>> >  		struct sgx_vepc *vepc;
>> >  		void *owner;
>> >  	};
>> >
>> > And in sgx_{alloc|free}_epc_page() we can use 'owner' instead.
>> >
>>
>> As I mentioned in cover letter and change log in 11/18, this series does 
>> not track virtual EPC.
>
> It's not about how does the cover letter says.  We cannot ignore the  
> fact that
> currently virtual EPC uses owner too.
>
> But given the virtual EPC code currently doesn't use the owner, I can  
> live with
> not having the 'vepc' member in the union now.

Ah, I forgot even though we don't use the owner field assigned by vepc, it  
is still passed into sgx_alloc/free_epc_page().

Will add back "void* owner" and use it for assignment inside  
sgx_alloc/free_epc_page().

Thanks

Haitao