linux-kernel - Re: [PATCH v3 03/25] x86/sgx: Wipe out EREMOVE from sgx_free_epc

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Message-ID: <YEyX4V7BcS3MZNzp@kernel.org>
Date:   Sat, 13 Mar 2021 12:45:53 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Kai Huang <kai.huang@...el.com>, kvm@...r.kernel.org,
        x86@...nel.org, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org, luto@...nel.org,
        dave.hansen@...el.com, rick.p.edgecombe@...el.com,
        haitao.huang@...el.com, pbonzini@...hat.com, bp@...en8.de,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com
Subject: Re: [PATCH v3 03/25] x86/sgx: Wipe out EREMOVE from
 sgx_free_epc_page()

On Fri, Mar 12, 2021 at 01:21:54PM -0800, Sean Christopherson wrote:
> On Thu, Mar 11, 2021, Kai Huang wrote:
> > From: Jarkko Sakkinen <jarkko@...nel.org>
> > 
> > EREMOVE takes a page and removes any association between that page and
> > an enclave.  It must be run on a page before it can be added into
> > another enclave.  Currently, EREMOVE is run as part of pages being freed
> > into the SGX page allocator.  It is not expected to fail.
> > 
> > KVM does not track how guest pages are used, which means that SGX
> > virtualization use of EREMOVE might fail.
> > 
> > Break out the EREMOVE call from the SGX page allocator.  This will allow
> > the SGX virtualization code to use the allocator directly.  (SGX/KVM
> > will also introduce a more permissive EREMOVE helper).
> > 
> > Implement original sgx_free_epc_page() as sgx_encl_free_epc_page() to be
> > more specific that it is used to free EPC page assigned to one enclave.
> > Print an error message when EREMOVE fails to explicitly call out EPC
> > page is leaked, and requires machine reboot to get leaked pages back.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> > Co-developed-by: Kai Huang <kai.huang@...el.com>
> > Acked-by: Jarkko Sakkinen <jarkko@...nel.org>
> > Signed-off-by: Kai Huang <kai.huang@...el.com>
> > ---
> > v2->v3:
> > 
> >  - Fixed bug during copy/paste which results in SECS page and va pages are not
> >    correctly freed in sgx_encl_release() (sorry for the mistake).
> >  - Added Jarkko's Acked-by.
> 
> That Acked-by should either be dropped or moved above Co-developed-by to make
> checkpatch happy.
> 
> Reviewed-by: Sean Christopherson <seanjc@...gle.com>

Oops, my bad. Yup, ack should be removed.

/Jarkko