From: "Luck, Tony" <tony.luck@intel.com>
To: "Pan, Jacob jun" <jacob.jun.pan@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
"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>
Subject: RE: [PATCH 5/7] x86/mmu: Allocate/free PASID
Date: Tue, 28 Apr 2020 20:59:43 +0000 [thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F7F608EE2@ORSMSX115.amr.corp.intel.com> (raw)
In-Reply-To: <20200428134200.000010f7@intel.com>
>> 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.
>>
> Are you suggesting we should let driver also hold a reference of the
> PASID?
The sequence for bare metal is:
process is queuing requests to DSA
process exits (either deliberately, or crashes, or is killed)
kernel does exit processing
DSA driver is called as part of tear down of "mm"
issues drain/flush commands to ensure that all
queued operations on the PASID for this mm have
completed
PASID can be freed
There's a 1:1 map from "mm" to PASID ... so reference counting seems
like overkill. Once the kernel is in the "exit" path, we know that no more
work can be queued using this PASID.
-Tony
WARNING: multiple messages have this Message-ID (diff)
From: "Luck, Tony" <tony.luck@intel.com>
To: "Pan, Jacob jun" <jacob.jun.pan@intel.com>
Cc: "Yu, Fenghua" <fenghua.yu@intel.com>,
"Jiang, Dave" <dave.jiang@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
x86 <x86@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
David Woodhouse <dwmw2@infradead.org>
Subject: RE: [PATCH 5/7] x86/mmu: Allocate/free PASID
Date: Tue, 28 Apr 2020 20:59:43 +0000 [thread overview]
Message-ID: <3908561D78D1C84285E8C5FCA982C28F7F608EE2@ORSMSX115.amr.corp.intel.com> (raw)
In-Reply-To: <20200428134200.000010f7@intel.com>
>> 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.
>>
> Are you suggesting we should let driver also hold a reference of the
> PASID?
The sequence for bare metal is:
process is queuing requests to DSA
process exits (either deliberately, or crashes, or is killed)
kernel does exit processing
DSA driver is called as part of tear down of "mm"
issues drain/flush commands to ensure that all
queued operations on the PASID for this mm have
completed
PASID can be freed
There's a 1:1 map from "mm" to PASID ... so reference counting seems
like overkill. Once the kernel is in the "exit" path, we know that no more
work can be queued using this PASID.
-Tony
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2020-04-28 21:00 UTC|newest]
Thread overview: 74+ 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 ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 1/7] docs: x86: Add a documentation for ENQCMD Fenghua Yu
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 11:02 ` Thomas Gleixner
2020-04-26 11:02 ` Thomas Gleixner
2020-04-27 20:13 ` Fenghua Yu
2020-04-27 20:13 ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 2/7] x86/cpufeatures: Enumerate ENQCMD and ENQCMDS instructions Fenghua Yu
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 11:06 ` Thomas Gleixner
2020-04-26 11:06 ` Thomas Gleixner
2020-04-27 20:17 ` Fenghua Yu
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
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 11:17 ` Thomas Gleixner
2020-04-26 11:17 ` Thomas Gleixner
2020-04-27 20:33 ` Fenghua Yu
2020-04-27 20:33 ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 4/7] x86/msr-index: Define IA32_PASID MSR Fenghua Yu
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 11:22 ` Thomas Gleixner
2020-04-26 11:22 ` Thomas Gleixner
2020-04-27 20:50 ` Fenghua Yu
2020-04-27 20:50 ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 5/7] x86/mmu: Allocate/free PASID Fenghua Yu
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 14:55 ` Thomas Gleixner
2020-04-26 14:55 ` Thomas Gleixner
2020-04-27 22:18 ` Fenghua Yu
2020-04-27 22:18 ` Fenghua Yu
2020-04-27 23:44 ` Thomas Gleixner
2020-04-27 23:44 ` Thomas Gleixner
2020-04-28 18:21 ` Jacob Pan (Jun)
2020-04-28 18:21 ` Jacob Pan (Jun)
2020-04-28 18:54 ` Thomas Gleixner
2020-04-28 18:54 ` Thomas Gleixner
2020-04-28 19:07 ` Luck, Tony
2020-04-28 19:07 ` Luck, Tony
2020-04-28 20:42 ` Jacob Pan (Jun)
2020-04-28 20:42 ` Jacob Pan (Jun)
2020-04-28 20:59 ` Luck, Tony [this message]
2020-04-28 20:59 ` Luck, Tony
2020-04-28 22:13 ` Jacob Pan (Jun)
2020-04-28 22:13 ` Jacob Pan (Jun)
2020-04-28 22:32 ` Luck, Tony
2020-04-28 22:32 ` Luck, Tony
2020-04-28 20:40 ` Jacob Pan (Jun)
2020-04-28 20:40 ` Jacob Pan (Jun)
2020-04-28 20:57 ` Fenghua Yu
2020-04-28 20:57 ` Fenghua Yu
2020-03-30 19:33 ` [PATCH 6/7] x86/traps: Fix up invalid PASID Fenghua Yu
2020-03-30 19:33 ` Fenghua Yu
2020-04-26 15:25 ` Thomas Gleixner
2020-04-26 15:25 ` Thomas Gleixner
2020-04-27 20:11 ` Fenghua Yu
2020-04-27 20:11 ` Fenghua Yu
2020-04-28 0:13 ` Thomas Gleixner
2020-04-28 0:13 ` Thomas Gleixner
2020-04-27 22:46 ` Raj, Ashok
2020-04-27 22:46 ` Raj, Ashok
2020-04-27 23:08 ` Luck, Tony
2020-04-27 23:08 ` Luck, Tony
2020-04-28 0:20 ` Thomas Gleixner
2020-04-28 0:20 ` Thomas Gleixner
2020-04-28 0:54 ` Thomas Gleixner
2020-04-28 0:54 ` Thomas Gleixner
2020-04-28 1:08 ` Raj, Ashok
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
2020-03-30 19:33 ` Fenghua Yu
2020-04-22 20:41 ` [PATCH 0/7] x86: tag application address space for devices Fenghua Yu
2020-04-22 20:41 ` Fenghua Yu
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