linux-kernel - Re: [PATCH 09/25] x86/sgx: Keep record of SGX page type

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Date:   Sun, 5 Dec 2021 01:03:30 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Reinette Chatre <reinette.chatre@...el.com>
Cc:     dave.hansen@...ux.intel.com, tglx@...utronix.de, bp@...en8.de,
        luto@...nel.org, mingo@...hat.com, linux-sgx@...r.kernel.org,
        x86@...nel.org, seanjc@...gle.com, kai.huang@...el.com,
        cathy.zhang@...el.com, cedric.xing@...el.com,
        haitao.huang@...el.com, mark.shanahan@...el.com, hpa@...or.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/25] x86/sgx: Keep record of SGX page type

On Wed, Dec 01, 2021 at 11:23:07AM -0800, Reinette Chatre wrote:
> SGX2 functions are not allowed on all page types. For example,
> ENCLS[EMODPR] is only allowed on regular SGX enclave pages and
> ENCLS[EMODPT] is only allowed on TCS and regular pages. If these
> functions are attempted on another type of page the hardware would
> trigger a fault.
> 
> Keep a record of the SGX page type so that there is more
> certainty whether an SGX2 instruction can succeed and faults
> can be treated as real failures.
> 
> The page type is made to be a property of struct sgx_encl_page
> and thus does not cover the VA page type. VA pages are maintained
> in separate structures and thus their type can be determined in
> a different way. The SGX2 instructions being supported do not
> operate on VA pages and this is thus not a scenario needing to
> be covered at this time.
> 
> With the protection bits consuming 16 bits of the unsigned long
> there is room available in the bitfield to include the page type
> information without increasing the space consumed by the struct.
> 
> Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>

I think this is needed for any formation of these patches, and
I cannot forsee it done by any other way, so
 
Acked-by: Jarkko Sakkinen <jarkko@...nel.org>

/Jarkko