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From: "Luck, Tony" <tony.luck@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>
Cc: "Yu, Fenghua" <fenghua.yu@intel.com>,
	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>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Jiang, Dave" <dave.jiang@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>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>
Subject: RE: [PATCH 5/7] x86/mmu: Allocate/free PASID
Date: Tue, 28 Apr 2020 19:07:25 +0000	[thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F7F608BE9@ORSMSX115.amr.corp.intel.com> (raw)
In-Reply-To: <87tv13o306.fsf@nanos.tec.linutronix.de>

> If fd release cleans up then how should there be something in flight at
> the final mmdrop?

ENQCMD from the user is only synchronous in that it lets the user know their
request has been added to a queue (or not).  Execution of the request may happen
later (if the device is busy working on requests for other users).  The request will
take some time to complete. Someone told me the theoretical worst case once,
which I've since forgotten, but it can be a long time.

So the driver needs to use flush/drain operations to make sure all the in-flight
work has completed before releasing/re-using the PASID.

-Tony

  reply	other threads:[~2020-04-28 19:07 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-30 19:33 [PATCH 0/7] x86: tag application address space for devices Fenghua Yu
2020-03-30 19:33 ` [PATCH 1/7] docs: x86: Add a documentation for ENQCMD Fenghua Yu
2020-04-26 11:02   ` Thomas Gleixner
2020-04-27 20:13     ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 2/7] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu
2020-04-26 11:06   ` Thomas Gleixner
2020-04-27 20:17     ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 3/7] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature Fenghua Yu
2020-04-26 11:17   ` Thomas Gleixner
2020-04-27 20:33     ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 4/7] x86/msr-index: Define IA32_PASID MSR Fenghua Yu
2020-04-26 11:22   ` Thomas Gleixner
2020-04-27 20:50     ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 5/7] x86/mmu: Allocate/free PASID Fenghua Yu
2020-04-26 14:55   ` Thomas Gleixner
2020-04-27 22:18     ` Fenghua Yu
2020-04-27 23:44       ` Thomas Gleixner
2020-04-28 18:21     ` Jacob Pan (Jun)
2020-04-28 18:54       ` Thomas Gleixner
2020-04-28 19:07         ` Luck, Tony [this message]
2020-04-28 20:42           ` Jacob Pan (Jun)
2020-04-28 20:59             ` Luck, Tony
2020-04-28 22:13               ` Jacob Pan (Jun)
2020-04-28 22:32                 ` Luck, Tony
2020-04-28 20:40         ` Jacob Pan (Jun)
2020-04-28 20:57     ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 6/7] x86/traps: Fix up invalid PASID Fenghua Yu
2020-04-26 15:25   ` Thomas Gleixner
2020-04-27 20:11     ` Fenghua Yu
2020-04-28  0:13       ` Thomas Gleixner
2020-04-27 22:46     ` Raj, Ashok
2020-04-27 23:08       ` Luck, Tony
2020-04-28  0:20         ` Thomas Gleixner
2020-04-28  0:54       ` Thomas Gleixner
2020-04-28  1:08         ` Raj, Ashok
2020-03-30 19:33 ` [PATCH 7/7] x86/process: Clear PASID state for a newly forked/cloned thread Fenghua Yu
2020-04-22 20:41 ` [PATCH 0/7] x86: tag application address space for devices Fenghua Yu

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