linux-kernel - Re: [PATCH 07/25] x86/sgx: Move PTE zap code to separate function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YdgxZFvjrPQN2D8S@iki.fi>
Date:   Fri, 7 Jan 2022 14:26:12 +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 07/25] x86/sgx: Move PTE zap code to separate function

On Thu, Jan 06, 2022 at 09:46:35AM -0800, Reinette Chatre wrote:
> Hi Jarkko,
> 
> On 12/28/2021 6:55 AM, Jarkko Sakkinen wrote:
> > On Mon, Dec 13, 2021 at 02:11:26PM -0800, Reinette Chatre wrote:
> >> Hi Jarkko,
> >>
> >> On 12/10/2021 11:52 PM, Jarkko Sakkinen wrote:
> >>> On Mon, 2021-12-06 at 13:30 -0800, Reinette Chatre wrote:
> >>>> Hi Jarkko,
> >>>>
> >>>> On 12/4/2021 2:59 PM, Jarkko Sakkinen wrote:
> >>>>> On Wed, Dec 01, 2021 at 11:23:05AM -0800, Reinette Chatre wrote:
> >>>>>> The SGX reclaimer removes page table entries pointing to pages that are
> >>>>>> moved to swap. SGX2 enables changes to pages belonging to an initialized
> >>>>>> enclave, for example changing page permissions. Supporting SGX2 requires
> >>>>>> this ability to remove page table entries that is available in the
> >>>>>> SGX reclaimer code.
> >>>>>
> >>>>> Missing: why SGX2 requirest this?
> >>>>
> >>>> The above paragraph states that SGX2 needs to remove page table entries
> >>>> because it modifies page permissions. Could you please elaborate what is
> >>>> missing?
> >>>
> >>> It does not say why SGX2 requires an ability to remove page table entries.
> >>
> >> Are you saying that modification of EPCM page permissions is not a reason to
> >> remove page table entries pointing to those pages?
> > 
> > So you have:
> > 
> > "Supporting SGX2 requires this ability to remove page table entries that is
> > available in the SGX reclaimer code"
> > 
> > Just write down where you need this ability (briefly).
> 
> Will do. I will expand the current permission changing text and also add the need
> for this ability when regular pages are changed to TCS pages. TCS pages may not
> be accessed by enclave code so when a regular page becomes a TCS page any page
> table entries pointing to it should be removed.

Thank you, sounds good.

BR,
Jarkko