linux-kernel - Re: [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF

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Date:   Wed, 16 Sep 2020 23:30:08 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jethro Beekman <jethro@...tanix.com>,
        Darren Kenny <darren.kenny@...cle.com>,
        Borislav Petkov <bp@...e.de>, akpm@...ux-foundation.org,
        andriy.shevchenko@...ux.intel.com, asapek@...gle.com,
        cedric.xing@...el.com, chenalexchen@...gle.com,
        conradparker@...gle.com, cyhanish@...gle.com,
        dave.hansen@...el.com, haitao.huang@...el.com,
        josh@...htriplett.org, kai.huang@...el.com, kai.svahn@...el.com,
        kmoy@...gle.com, ludloff@...gle.com, luto@...nel.org,
        nhorman@...hat.com, npmccallum@...hat.com, puiterwijk@...hat.com,
        rientjes@...gle.com, tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX

On Wed, Sep 16, 2020 at 01:44:48PM +0200, Borislav Petkov wrote:
> On Tue, Sep 15, 2020 at 02:28:21PM +0300, Jarkko Sakkinen wrote:
> > From: Sean Christopherson <sean.j.christopherson@...el.com>
> > 
> > Include SGX bit to the PF error codes and throw SIGSEGV with PF_SGX when
> > a #PF with SGX set happens.
> > 
> > CPU throws a #PF with the SGX set in the event of Enclave Page Cache Map
> > (EPCM) conflict. The EPCM is a CPU-internal table, which describes the
> > properties for a enclave page. Enclaves are measured and signed software
> > entities, which SGX hosts. [1]
> > 
> > Although the primary purpose of the EPCM conflict checks  is to prevent
> > malicious accesses to an enclave, an illegit access can happen also for
> > legit reasons.
> > 
> > All SGX reserved memory, including EPCM is encrypted with a transient key
> > that does not survive from the power transition. Throwing a SIGSEGV allows
> > user space software to react when this happens (e.g. recreate the enclave,
> > which was invalidated).
> > 
> > [1] Intel SDM: 36.5.1 Enclave Page Cache Map (EPCM)
> > 
> > Acked-by: Jethro Beekman <jethro@...tanix.com>
> > Reviewed-by: Darren Kenny <darren.kenny@...cle.com>
> > Reviewed-by: Borislav Petkov <bp@...e.de>
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >  arch/x86/include/asm/traps.h | 14 ++++++++------
> 
> The SEV-ES patchset moved that to arch/x86/include/asm/trap_pf.h but
> fixing that up is real easy. Simply do this search-replace
> 
> s!arch/x86/include/asm/traps.h!arch/x86/include/asm/trap_pf.h!
> 
> on this patch.

Hey, I just did

git fetch mainline && git rebase mainline/master

Zero conflicts and there is no trap_pf.h yet. So this is not yet in
Linus' tree?

/Jarkko