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Message-ID: <1702295227b9276e051a0efee8af1475cba27407.camel@kernel.org>
Subject: Re: [PATCH v7 3/7] x86/sgx: Initial poison handling for dirty and
 free pages
From:   Jarkko Sakkinen <jarkko@kernel.org>
To:     "Luck, Tony" <tony.luck@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        "Hansen, Dave" <dave.hansen@intel.com>
Cc:     "Zhang, Cathy" <cathy.zhang@intel.com>,
        "linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>
Date:   Tue, 28 Sep 2021 23:11:30 +0300
In-Reply-To: <ca3bb671a49141608ac981012091c3ea@intel.com>
References: <20210922182123.200105-1-tony.luck@intel.com>
         <20210927213452.212470-1-tony.luck@intel.com>
         <20210927213452.212470-4-tony.luck@intel.com>
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On Tue, 2021-09-28 at 15:41 +0000, Luck, Tony wrote:
> > > Add debugfs files /sys/kernel/debug/sgx/poison_page_list so that syst=
em
> > > administrators get a list of those pages that have been dropped becau=
se
> > > of poison.
> >=20
> > So, what would a sysadmin do with that detailed information?
>=20
> It's going to be a rare case that there are any poisoned pages on that li=
st
> (a large enough cluster will have some systems that have uncorrected
> recoverable errors in SGX EPC memory).
>=20
> Even when there are some poisoned pages, there will only be a few. System=
s
> that have thousands of pages with uncorrected memory errors will surely c=
rash
> because one of those errors is going to either trigger an error marked as=
 fatal,
> or the error won=E2=80=99t be recoverable by Linux because it is in kerne=
l memory.
>=20
> A sysadmin might add a script to run during system shutdown (or periodica=
lly
> during run-time) to save the poison page list. Then at startup run:
>=20
> for addr in `cat saved_sgx_poison_page_list`
> do
> 	echo $addr > /sys/devices/system/memory/hard_offline_page
> done
>=20
> to make poison persistent across reboots.
>=20
> -Tony

Couldn't it be a blob with 8 bytes for each address?

/Jarkko