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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86@kernel.org, platform-driver-x86@vger.kernel.org,
	linux-sgx@vger.kernel.org, dave.hansen@intel.com,
	nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com,
	shay.katz-zamir@intel.com, haitao.huang@intel.com,
	andriy.shevchenko@linux.intel.com, tglx@linutronix.de,
	kai.svahn@intel.com, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	David Wang <davidwang@zhaoxin.com>,
	"Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>,
	Jia Zhang <qianyue.zj@alibaba-inc.com>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v16 06/22] x86/cpu/intel: Detect SGX support and update caps appropriately
Date: Wed, 7 Nov 2018 17:58:13 +0200
Message-ID: <20181107155813.GA9730@linux.intel.com> (raw)
In-Reply-To: <1541512681.7839.14.camel@intel.com>

On Tue, Nov 06, 2018 at 05:58:01AM -0800, Sean Christopherson wrote:
> On Tue, 2018-11-06 at 15:45 +0200, Jarkko Sakkinen wrote:
> > From: Sean Christopherson <sean.j.christopherson@intel.com>
> > 
> > Similar to other large Intel features such as VMX and TXT, SGX must be
> > explicitly enabled in IA32_FEATURE_CONTROL MSR to be truly usable.
> > Clear all SGX related capabilities if SGX is not fully enabled in
> > IA32_FEATURE_CONTROL or if the SGX1 instruction set isn't supported
> > (impossible on bare metal, theoretically possible in a VM if the VMM is
> > doing something weird).
> > 
> > Like SGX itself, SGX Launch Control must be explicitly enabled via a
> > flag in IA32_FEATURE_CONTROL. Clear the SGX_LC capability if Launch
> > Control is not fully enabled (or obviously if SGX itself is disabled).
> > 
> > Note that clearing X86_FEATURE_SGX_LC creates a bit of a conundrum
> > regarding the SGXLEPUBKEYHASH MSRs, as it may be desirable to read the
> > MSRs even if they are not writable, e.g. to query the configured key,
> > but clearing the capability leaves no breadcrum for discerning whether
> > or not the MSRs exist.  But, such usage will be rare (KVM is the only
> > known case at this time) and not performance critical, so it's not
> > unreasonable to require the use of rdmsr_safe().  Clearing the cap bit
> > eliminates the need for an additional flag to track whether or not
> > Launch Control is truly enabled, which is what we care about the vast
> > majority of the time.
> > 
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> >  arch/x86/kernel/cpu/intel.c | 37 +++++++++++++++++++++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> > 
> > diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> > index fc3c07fe7df5..8a20a193d399 100644
> > --- a/arch/x86/kernel/cpu/intel.c
> > +++ b/arch/x86/kernel/cpu/intel.c
> > @@ -596,6 +596,40 @@ static void detect_tme(struct cpuinfo_x86 *c)
> >  	c->x86_phys_bits -= keyid_bits;
> >  }
> >  
> > +static void detect_sgx(struct cpuinfo_x86 *c)
> > +{
> > +	unsigned long long fc;
> > +
> > +	rdmsrl(MSR_IA32_FEATURE_CONTROL, fc);
> > +	if (!(fc & FEATURE_CONTROL_LOCKED)) {
> > +		pr_err_once("sgx: IA32_FEATURE_CONTROL MSR is not locked\n");
> > +		goto out_unsupported;
> > +	}
> > +
> > +	if (!(fc & FEATURE_CONTROL_SGX_ENABLE)) {
> > +		pr_err_once("sgx: not enabled in IA32_FEATURE_CONTROL MSR\n");
> > +		goto out_unsupported;
> > +	}
> > +
> > +	if (!cpu_has(c, X86_FEATURE_SGX1)) {
> > +		pr_err_once("sgx: SGX1 instruction set not supported\n");
> > +		goto out_unsupported;
> > +	}
> > +
> > +	if (!(fc & FEATURE_CONTROL_SGX_LE_WR)) {
> 
> FEATURE_CONTROL_SGX_LE_WR isn't added until patch 13/22.  The patch
> can simply be moved earlier in the series if you want to introduce
> the full detect_sgx() in a single patch.  The only reason SGX_LE_WR
> was added later in the series was to bundle the Launch Control stuff
> together.

Ugh, sorry. Had this is mind when I started working on v16 changes :-(

/Jarkko

  parent reply index

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-06 13:45 [PATCH v16 00/22] Intel SGX1 support Jarkko Sakkinen
2018-11-06 13:45 ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 01/22] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 02/22] x86/cpufeatures: Add Intel-defined SGX feature bit Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 03/22] x86/cpufeatures: Add SGX sub-features (as Linux-defined bits) Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 04/22] x86/msr: Add IA32_FEATURE_CONTROL.SGX_ENABLE definition Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 05/22] x86/cpufeatures: Add Intel-defined SGX_LC feature bit Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 06/22] x86/cpu/intel: Detect SGX support and update caps appropriately Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:58   ` Sean Christopherson
2018-11-06 13:58     ` Sean Christopherson
2018-11-07 15:58     ` Jarkko Sakkinen [this message]
2018-11-06 13:45 ` [PATCH v16 07/22] x86/mm: x86/sgx: Add new 'PF_SGX' page fault error code bit Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 08/22] x86/mm: x86/sgx: Signal SIGSEGV for userspace #PFs w/ PF_SGX Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 09/22] x86/sgx: Define SGX1 and SGX2 ENCLS leafs Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 10/22] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 11/22] x86/sgx: Add SGX1 and SGX2 architectural data structures Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 12/22] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 13/22] x86/msr: Add SGX Launch Control MSR definitions Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 14/22] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 15/22] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 16/22] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 17/22] x86/sgx: Add sgx_einit() for initializing enclaves Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 18/22] platform/x86: Intel SGX driver Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 16:40   ` Sean Christopherson
2018-11-06 16:57     ` Dave Hansen
2018-11-07 16:37     ` Jarkko Sakkinen
2018-11-07 18:00       ` Sean Christopherson
2018-11-07 18:00         ` Sean Christopherson
2018-11-08 14:46         ` Jarkko Sakkinen
2018-11-15 20:00           ` Jarkko Sakkinen
2018-11-15 20:04             ` Jarkko Sakkinen
2018-11-15 20:16               ` Jarkko Sakkinen
2018-11-21 11:46                 ` Jarkko Sakkinen
2018-11-07 10:29   ` David Laight
2018-11-06 13:45 ` [PATCH v16 19/22] platform/x86: sgx: Add swapping functionality to the " Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:45 ` [PATCH v16 20/22] x86/sgx: Add a simple swapper for the EPC memory manager Jarkko Sakkinen
2018-11-06 13:45   ` Jarkko Sakkinen
2018-11-06 13:46 ` [PATCH v16 21/22] platform/x86: ptrace() support for the SGX driver Jarkko Sakkinen
2018-11-06 13:46   ` Jarkko Sakkinen
2018-11-06 13:46 ` [PATCH v16 22/22] x86/sgx: SGX documentation Jarkko Sakkinen
2018-11-06 13:46   ` Jarkko Sakkinen
2018-11-27 20:13   ` Pavel Machek

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