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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Haitao Huang <haitao.huang@linux.intel.com>,
	x86@kernel.org, linux-sgx@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Jethro Beekman <jethro@fortanix.com>,
	Chunyang Hui <sanqian.hcy@antfin.com>,
	Jordan Hand <jorhand@linux.microsoft.com>,
	Nathaniel McCallum <npmccallum@redhat.com>,
	Seth Moore <sethmo@google.com>,
	Darren Kenny <darren.kenny@oracle.com>,
	Suresh Siddha <suresh.b.siddha@intel.com>,
	akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com,
	asapek@google.com, bp@alien8.de, cedric.xing@intel.com,
	chenalexchen@google.com, conradparker@google.com,
	cyhanish@google.com, dave.hansen@intel.com,
	haitao.huang@intel.com, josh@joshtriplett.org,
	kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com,
	ludloff@google.com, luto@kernel.org, nhorman@redhat.com,
	puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de,
	yaozhangx@google.com
Subject: Re: [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES
Date: Fri, 18 Sep 2020 15:20:29 +0300	[thread overview]
Message-ID: <20200918122029.GA27028@linux.intel.com> (raw)
In-Reply-To: <20200918020940.GA14678@sjchrist-ice>

On Thu, Sep 17, 2020 at 07:09:40PM -0700, Sean Christopherson wrote:
> On Thu, Sep 17, 2020 at 01:35:10PM -0500, Haitao Huang wrote:
> > On Thu, 17 Sep 2020 11:02:06 -0500, Jarkko Sakkinen
> > <jarkko.sakkinen@linux.intel.com> wrote:
> > > 
> > > Right, I do get the OOM case but wouldn't in that case the reasonable
> > > thing to do destroy the enclave that is not even running? I mean that
> > > means that we are globally out of EPC.
> > > 
> > 
> > I would say it could be a policy, but not the only one. If it does not make
> > much difference to kernel, IMHO we should  not set it in stone now.
> > Debugging is also huge benefit to me.
> 
> Agreed, an EPC cgroup is the proper way to define/enforce what happens when
> there is EPC pressure.  E.g. if process A is consuming 99% of the EPC, then
> it doesn't make sense to unconditionally kill enclaves from process B.  If
> the admin wants to give process A priority, so be it, but such a decision
> shouldn't be baked into the kernel.
> 
> This series obviously doesn't provide an EPC cgroup, but that doesn't mean
> we can't make decisions that will play nice with a cgroup in the future.

Here's the core issue why the API "as is used to be" does not work:

	if (ret == -EIO) {
		mutex_lock(&encl->lock);
		sgx_encl_destroy(encl);
		mutex_unlock(&encl->lock);
	}

It would be better to instead whitelist *when* the enclave is preserved.

	if (ret != -ENOMEM) {
		mutex_lock(&encl->lock);
		sgx_encl_destroy(encl);
		mutex_unlock(&encl->lock);
	}

That is the information we *deterministically* want to know. Otherwise,
we will live in ultimate chaos.

Only this way can caller know when there are means to continue, and when
to quit. I.e. the code is whitelisting wrong way around currently.

/Jarkko

  reply	other threads:[~2020-09-18 12:20 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 11:04 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:04 ` [PATCH v38 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
     [not found]   ` <op.0q2prldowjvjmi@mqcpg7oapc828.gar.corp.intel.com>
2020-09-17 16:02     ` Jarkko Sakkinen
2020-09-17 18:35       ` Haitao Huang
2020-09-18  2:09         ` Sean Christopherson
2020-09-18 12:20           ` Jarkko Sakkinen [this message]
2020-09-18 12:39             ` Jarkko Sakkinen
     [not found]               ` <20200919000918.GB21189@sjchrist-ice>
2020-09-21 11:41                 ` Jarkko Sakkinen
2020-09-21 16:46                   ` Sean Christopherson
2020-09-21 18:49                     ` Jarkko Sakkinen
2020-09-21 19:44                       ` Jarkko Sakkinen
2020-09-21 19:57                         ` Sean Christopherson
2020-09-21 21:24                           ` Jarkko Sakkinen
2020-09-21 19:58                         ` Jarkko Sakkinen
2020-09-17 16:03     ` Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 15/24] x86/sgx: Enable provisioning for remote attestation Jarkko Sakkinen
2020-10-01 17:17   ` Sean Christopherson
2020-09-15 11:05 ` [PATCH v38 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-28  1:32   ` Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-09-15 11:28 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen

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