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From: Andy Lutomirski <luto@amacapital.net>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Yu, Fenghua" <fenghua.yu@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	H Peter Anvin <hpa@zytor.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	Joerg Roedel <joro@8bytes.org>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	"Yu, Yu-cheng" <yu-cheng.yu@intel.com>,
	"Mehta, Sohil" <sohil.mehta@intel.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	amd-gfx <amd-gfx@lists.freedesktop.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v2 12/12] x86/traps: Fix up invalid PASID
Date: Mon, 15 Jun 2020 14:18:39 -0700	[thread overview]
Message-ID: <E39A5DE2-5615-41FF-9953-4F4C4E8499D8@amacapital.net> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28F7F66C849@ORSMSX115.amr.corp.intel.com>



> On Jun 15, 2020, at 1:56 PM, Luck, Tony <tony.luck@intel.com> wrote:
> 
> 
>> 
>> Are we planning to keep PASID live once a task has used it once or are we going to swap it lazily?  If the latter, a percpu variable might be better.
> 
> Current plan is "touch it once and the task owns it until exit(2)"
> 
> Maybe someday in the future when we have data on how applications
> actually use accelerators we could look at something more complex
> if usage patterns look like it would be beneficial.
> 
> 

So what’s the RDMSR for?  Surely you
have some state somewhere that says “this task has a PASID.”  Can’t you just make sure that stays in sync with the MSR?  Then, on #GP, if the task already has a PASID, you know the MSR is set.

  reply	other threads:[~2020-06-15 21:18 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-13  0:41 [PATCH v2 00/12] x86: tag application address space for devices Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 01/12] iommu: Change type of pasid to unsigned int Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 02/12] ocxl: " Fenghua Yu
2020-06-18  8:05   ` Frederic Barrat
2020-06-18 15:37     ` Fenghua Yu
2020-06-18 16:56       ` Frederic Barrat
2020-06-13  0:41 ` [PATCH v2 03/12] iommu/vt-d: Change flags type to unsigned int in binding mm Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 04/12] docs: x86: Add documentation for SVA (Shared Virtual Addressing) Fenghua Yu
2020-06-13 12:17   ` Lu Baolu
2020-06-15 23:16     ` Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 05/12] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 06/12] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 07/12] x86/msr-index: Define IA32_PASID MSR Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 08/12] mm: Define pasid in mm Fenghua Yu
2020-06-16  8:28   ` Jean-Philippe Brucker
2020-06-16 15:11     ` Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 09/12] fork: Clear PASID for new mm Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 10/12] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu
2020-06-13  0:41 ` [PATCH v2 11/12] x86/mmu: Allocate/free PASID Fenghua Yu
2020-06-13 13:07   ` Lu Baolu
2020-06-15  2:13   ` Lu Baolu
2020-06-13  0:41 ` [PATCH v2 12/12] x86/traps: Fix up invalid PASID Fenghua Yu
2020-06-15  7:53   ` Peter Zijlstra
2020-06-15  7:56   ` Peter Zijlstra
2020-06-15 15:48     ` Fenghua Yu
2020-06-15 16:03       ` Peter Zijlstra
2020-06-15 17:11         ` Luck, Tony
2020-06-15 18:12         ` Fenghua Yu
2020-06-15 18:31           ` Peter Zijlstra
2020-06-15 18:55             ` Fenghua Yu
2020-06-15 19:09               ` Peter Zijlstra
2020-06-15 20:17                 ` Fenghua Yu
2020-06-15 20:51                   ` Andy Lutomirski
2020-06-15 20:56                     ` Luck, Tony
2020-06-15 21:18                       ` Andy Lutomirski [this message]
2020-06-15 21:24                         ` Luck, Tony
2020-06-15 21:53                   ` Peter Zijlstra
2020-06-16 23:23                 ` Fenghua Yu
2020-06-17  8:31                   ` Peter Zijlstra
2020-06-15 18:19         ` Raj, Ashok
2020-06-15 18:32           ` Peter Zijlstra
2020-06-15  7:52 ` [PATCH v2 00/12] x86: tag application address space for devices Peter Zijlstra
2020-06-15 14:53   ` Fenghua Yu

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