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Message-ID: <29373cabc9ba55463b16b7d8148722997840fbb5.camel@kernel.org>
Subject: Re: [PATCH v7 1/7] x86/sgx: Add new sgx_epc_page flag bit to mark
 in-use pages
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     Tony Luck <tony.luck@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Dave Hansen <dave.hansen@intel.com>
Cc:     Cathy Zhang <cathy.zhang@intel.com>, linux-sgx@vger.kernel.org
Date:   Tue, 28 Sep 2021 05:28:32 +0300
In-Reply-To: <20210927213452.212470-2-tony.luck@intel.com>
References: <20210922182123.200105-1-tony.luck@intel.com>
         <20210927213452.212470-1-tony.luck@intel.com>
         <20210927213452.212470-2-tony.luck@intel.com>
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On Mon, 2021-09-27 at 14:34 -0700, Tony Luck wrote:
> SGX EPC pages go through the following life cycle:
>=20
>         DIRTY ---> FREE ---> IN-USE --\
>                     ^                 |
>                     \-----------------/
>=20
> Recovery action for poison for a DIRTY or FREE page is simple. Just
> make sure never to allocate the page. IN-USE pages need some extra
> handling.
>=20
> Add a new flag bit SGX_EPC_PAGE_IN_USE that is set when a page
> is allocated and cleared when the page is freed.
>=20
> Notes:
>=20
> 1) These transitions are made while holding the node->lock so that
>    future code that checks the flags while holding the node->lock
>    can be sure that if the SGX_EPC_PAGE_IN_USE bit is set, then the
>    page is on the free list.
>=20
> 2) Initially while the pages are on the dirty list the
>    SGX_EPC_PAGE_IN_USE bit is set.
>=20
> Signed-off-by: Tony Luck <tony.luck@intel.com>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

/Jarkko