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

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Date:   Mon, 2 Oct 2023 11:05:16 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "tj@...nel.org" <tj@...nel.org>,
        "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "haitao.huang@...ux.intel.com" <haitao.huang@...ux.intel.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "jarkko@...nel.org" <jarkko@...nel.org>,
        "Mehta, Sohil" <sohil.mehta@...el.com>
CC:     "kristen@...ux.intel.com" <kristen@...ux.intel.com>,
        "Zhang, Bo" <zhanb@...rosoft.com>,
        "Li, Zhiquan1" <zhiquan1.li@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "mikko.ylinen@...ux.intel.com" <mikko.ylinen@...ux.intel.com>,
        "anakrish@...rosoft.com" <anakrish@...rosoft.com>,
        "yangjie@...rosoft.com" <yangjie@...rosoft.com>
Subject: Re: [PATCH v5 09/18] x86/sgx: Store struct sgx_encl when allocating
 new VA pages

On Fri, 2023-09-29 at 10:06 -0500, Haitao Huang wrote:
> 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().
> 
> 

And also sgx_setup_epc_section().