From: Andy Shevchenko <andy.shevchenko@gmail.com> To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>, Platform Driver <platform-driver-x86@vger.kernel.org>, <linux-sgx@vger.kernel.org>, Dave Hansen <dave.hansen@intel.com>, <sean.j.christopherson@intel.com>, <nhorman@redhat.com>, <npmccallum@redhat.com>, <serge.ayoun@intel.com>, <shay.katz-zamir@intel.com>, <haitao.huang@intel.com>, <mark.shanahan@intel.com>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, 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>, <davidwang@zhaoxin.com>, "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>, <qianyue.zj@alibaba-inc.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v15 14/23] x86/cpu/intel: Clear SGX_LC capability if not enabled in FEATURE_CONTROL Date: Sat, 3 Nov 2018 15:15:15 +0200 [thread overview] Message-ID: <CAHp75VctUJRTecG4rVHXm0uO18ZndMgqJgtNyG25HtSzJF5uzg@mail.gmail.com> (raw) In-Reply-To: <20181102231320.29164-15-jarkko.sakkinen@linux.intel.com> On Sat, Nov 3, 2018 at 1:17 AM Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote: > > From: Sean Christopherson <sean.j.christopherson@intel.com> > > 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. > @@ -618,6 +618,8 @@ static void detect_sgx(struct cpuinfo_x86 *c) > setup_clear_cpu_cap(X86_FEATURE_SGX1); > setup_clear_cpu_cap(X86_FEATURE_SGX2); > } > + if (unsupported || !(fc & FEATURE_CONTROL_SGX_LE_WR)) > + setup_clear_cpu_cap(X86_FEATURE_SGX_LC); > } A-ha, I see how you use this variable here (though it's still possible to get rid of it, choose what is better for readability / maintenance). -- With Best Regards, Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andy.shevchenko@gmail.com> To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>, Platform Driver <platform-driver-x86@vger.kernel.org>, linux-sgx@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>, sean.j.christopherson@intel.com, nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@intel.com, mark.shanahan@intel.com, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, 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>, davidwang@zhaoxin.com, "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>, qianyue.zj@alibaba-inc.com, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v15 14/23] x86/cpu/intel: Clear SGX_LC capability if not enabled in FEATURE_CONTROL Date: Sat, 3 Nov 2018 15:15:15 +0200 [thread overview] Message-ID: <CAHp75VctUJRTecG4rVHXm0uO18ZndMgqJgtNyG25HtSzJF5uzg@mail.gmail.com> (raw) Message-ID: <20181103131515.uzuMG-Sd4sg-ns2nYRk5BViGIsZjBKeUlQQfjGiXv_I@z> (raw) In-Reply-To: <20181102231320.29164-15-jarkko.sakkinen@linux.intel.com> On Sat, Nov 3, 2018 at 1:17 AM Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote: > > From: Sean Christopherson <sean.j.christopherson@intel.com> > > 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. > @@ -618,6 +618,8 @@ static void detect_sgx(struct cpuinfo_x86 *c) > setup_clear_cpu_cap(X86_FEATURE_SGX1); > setup_clear_cpu_cap(X86_FEATURE_SGX2); > } > + if (unsupported || !(fc & FEATURE_CONTROL_SGX_LE_WR)) > + setup_clear_cpu_cap(X86_FEATURE_SGX_LC); > } A-ha, I see how you use this variable here (though it's still possible to get rid of it, choose what is better for readability / maintenance). -- With Best Regards, Andy Shevchenko
next prev parent reply other threads:[~2018-11-03 13:15 UTC|newest] Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-02 23:10 [PATCH v15 00/23] Intel SGX1 Jarkko Sakkinen 2018-11-02 23:10 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 01/23] x86/sgx: Update MAINTAINERS Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 02/23] x86/cpufeatures: Add Intel-defined SGX feature bit Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:33 ` Borislav Petkov 2018-11-02 23:33 ` Borislav Petkov 2018-11-02 23:55 ` Jarkko Sakkinen 2018-11-02 23:55 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 03/23] x86/cpufeatures: Add SGX sub-features (as Linux-defined bits) Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 04/23] x86/msr: Add IA32_FEATURE_CONTROL.SGX_ENABLE definition Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 05/23] x86/cpu/intel: Detect SGX support and update caps appropriately Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-03 13:05 ` Andy Shevchenko 2018-11-03 13:05 ` Andy Shevchenko 2018-11-05 14:09 ` Jarkko Sakkinen 2018-11-05 14:09 ` Jarkko Sakkinen 2018-11-05 14:11 ` Jarkko Sakkinen 2018-11-05 14:11 ` Jarkko Sakkinen 2018-11-05 14:31 ` Andy Shevchenko 2018-11-05 14:31 ` Andy Shevchenko 2018-11-02 23:11 ` [PATCH v15 06/23] x86/mm: x86/sgx: Add new 'PF_SGX' page fault error code bit Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 07/23] x86/mm: x86/sgx: Signal SIGSEGV for userspace #PFs w/ PF_SGX Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 08/23] x86/sgx: Define SGX1 and SGX2 ENCLS leafs Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 09/23] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 10/23] x86/sgx: Add SGX1 and SGX2 architectural data structures Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 11/23] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-03 13:11 ` Andy Shevchenko 2018-11-03 13:11 ` Andy Shevchenko 2018-11-05 14:35 ` Jarkko Sakkinen 2018-11-05 14:35 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 12/23] x86/cpufeatures: Add Intel-defined SGX_LC feature bit Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 13/23] x86/msr: Add SGX Launch Control MSR definitions Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 14/23] x86/cpu/intel: Clear SGX_LC capability if not enabled in FEATURE_CONTROL Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-03 13:15 ` Andy Shevchenko [this message] 2018-11-03 13:15 ` Andy Shevchenko 2018-11-05 14:37 ` Jarkko Sakkinen 2018-11-05 14:37 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 15/23] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-03 13:17 ` Andy Shevchenko 2018-11-03 13:17 ` Andy Shevchenko 2018-11-05 17:30 ` Jarkko Sakkinen 2018-11-05 17:30 ` Jarkko Sakkinen 2018-11-05 20:39 ` Andy Shevchenko 2018-11-05 20:39 ` Andy Shevchenko 2018-11-06 12:03 ` Jarkko Sakkinen 2018-11-06 12:03 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 16/23] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-03 1:07 ` Jethro Beekman 2018-11-03 1:07 ` Jethro Beekman 2018-11-05 17:31 ` Jarkko Sakkinen 2018-11-05 17:31 ` Jarkko Sakkinen 2018-11-03 13:22 ` Andy Shevchenko 2018-11-03 13:22 ` Andy Shevchenko 2018-11-05 17:35 ` Jarkko Sakkinen 2018-11-05 17:35 ` Jarkko Sakkinen 2018-11-06 12:10 ` Jarkko Sakkinen 2018-11-06 12:10 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 17/23] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 18/23] x86/sgx: Add sgx_einit() for initializing enclaves Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 19/23] platform/x86: Intel SGX driver Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 20/23] platform/x86: sgx: Add swapping functionality to the " Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 21/23] x86/sgx: Add a simple swapper for the EPC memory manager Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 22/23] platform/x86: ptrace() support for the SGX driver Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-02 23:11 ` [PATCH v15 23/23] x86/sgx: Driver documentation Jarkko Sakkinen 2018-11-02 23:11 ` Jarkko Sakkinen 2018-11-04 8:15 ` Mike Rapoport 2018-11-04 8:15 ` Mike Rapoport 2018-11-05 17:39 ` Jarkko Sakkinen 2018-11-05 17:39 ` Jarkko Sakkinen 2018-11-05 20:27 ` Dave Hansen 2018-11-05 20:27 ` Dave Hansen 2018-11-06 5:49 ` Jarkko Sakkinen 2018-11-06 5:49 ` Jarkko Sakkinen 2018-11-06 6:20 ` Jarkko Sakkinen 2018-11-06 6:20 ` Jarkko Sakkinen 2018-11-06 16:45 ` Dave Hansen 2018-11-06 16:45 ` Dave Hansen 2018-11-07 16:30 ` Jarkko Sakkinen 2018-11-07 16:30 ` Jarkko Sakkinen 2018-11-07 17:09 ` Dave Hansen 2018-11-07 17:09 ` Dave Hansen 2018-11-08 14:39 ` Jarkko Sakkinen 2018-11-08 14:39 ` Jarkko Sakkinen 2018-11-08 19:20 ` Jarkko Sakkinen 2018-11-08 19:20 ` Jarkko Sakkinen 2018-11-13 15:13 ` Jarkko Sakkinen 2018-11-06 6:26 ` Jarkko Sakkinen 2018-11-06 6:26 ` Jarkko Sakkinen
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