From: Borislav Petkov <bp@alien8.de>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
Peter Zijlstra <peterz@infradead.org>, x86 <x86@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Dave Hansen <dave.hansen@intel.com>,
iommu@lists.linux-foundation.org, Ingo Molnar <mingo@redhat.com>,
Christoph Hellwig <hch@infradeed.org>,
Jacob Jun Pan <jacob.jun.pan@intel.com>,
H Peter Anvin <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH v4 12/12] x86/traps: Fix up invalid PASID
Date: Fri, 26 Jun 2020 20:15:50 +0200 [thread overview]
Message-ID: <20200626181550.GF27151@zn.tnic> (raw)
In-Reply-To: <20200626181000.GA22833@agluck-desk2.amr.corp.intel.com>
On Fri, Jun 26, 2020 at 11:10:00AM -0700, Luck, Tony wrote:
> Do we have a standard way of coding for a feature that depends on multiple
> other features? For this case the system needs to both suport the ENQCMD
> instruction, and also have kernel code that programs the IOMMU.
Yes, you need both. Consider distros enabling everything so that they
can ship a single kernel image.
> And/or guidance on when to use each of the very somewhat simlar looking
> boot_cpu_has()
> static_cpu_has()
See the comment over _static_cpu_has() in arch/x86/include/asm/cpufeature.h
In the exception path you should use the static_ variant.
> IS_ENABLED()
This is testing CONFIG_ settings, i.e., build time.
> cpu_feature_enabled()
This too, indirectly. See
arch/x86/include/asm/disabled-features.h
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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next prev parent reply other threads:[~2020-06-26 18:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 20:17 [PATCH v4 00/12] x86: tag application address space for devices Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 01/12] iommu: Change type of pasid to u32 Fenghua Yu
2020-06-26 1:13 ` Lu Baolu
2020-06-25 20:17 ` [PATCH v4 02/12] iommu/vt-d: Change flags type to unsigned int in binding mm Fenghua Yu
2020-06-26 1:14 ` Lu Baolu
2020-06-25 20:17 ` [PATCH v4 03/12] docs: x86: Add documentation for SVA (Shared Virtual Addressing) Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 04/12] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 05/12] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 06/12] x86/msr-index: Define IA32_PASID MSR Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 07/12] mm: Define pasid in mm Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 08/12] fork: Clear PASID for new mm Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 09/12] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 10/12] x86/mmu: Allocate/free PASID Fenghua Yu
2020-06-26 1:42 ` Lu Baolu
2020-06-25 20:17 ` [PATCH v4 11/12] sched: Define and initialize a flag to identify valid PASID in the task Fenghua Yu
2020-06-25 20:17 ` [PATCH v4 12/12] x86/traps: Fix up invalid PASID Fenghua Yu
2020-06-26 1:46 ` Lu Baolu
2020-06-26 9:44 ` Peter Zijlstra
2020-06-26 18:10 ` Luck, Tony
2020-06-26 18:15 ` Borislav Petkov [this message]
2020-06-26 18:23 ` Dave Hansen
2020-06-26 18:35 ` Fenghua Yu
2020-06-26 18:16 ` Fenghua Yu
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