Linux IOMMU Development
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From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Lu Baolu <baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: "Tian,
	Kevin" <kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"Raj, Ashok" <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Jean-Philippe Brucker
	<jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>,
	"Kumar,
	Sanjay K"
	<sanjay.k.kumar-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"Sun, Yi Y" <yi.y.sun-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"Pan,
	Jacob jun"
	<jacob.jun.pan-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH v5 02/12] iommu/vt-d: Manage scalalble mode PASID tables
Date: Wed, 5 Dec 2018 16:50:12 +0100	[thread overview]
Message-ID: <20181205155012.GC16835@8bytes.org> (raw)
In-Reply-To: <5c81008b-30e8-177d-0182-db366608562f-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

On Tue, Dec 04, 2018 at 01:58:06PM +0800, Lu Baolu wrote:
> This function is called in an unsleepable context.
> 
> spin_lock(&lock)
> [...]
> if (pasid_table_is_necessary)
> 	allocate_pasid_table(dev)
> [...]
> spin_unlock(&lock)
> 
> We can move it out of the lock range.
> 
> How about
> 
> if (pasid_table_is_necessary)
> 	pasid_table = allocate_pasid_table(dev)
> 
> spin_lock(&lock)
> [...]
> if (pasid_table_is_necessary)
> 	set_up_pasid_table(pasid_table)
> [...]
> spin_unlock(&lock)

Hmm, so when the IOMMU is configured in scalable mode we can just
allocate a pasid-table for the device when we set it up, right?

Scalable mode is a boot-time decision, so we know for sure whether we
need a pasid-table on device-setup time. And the device-setup code it
preemptable, so I think it this allocation should be outside of any
spin-locked section.


	Joerg

  parent reply	other threads:[~2018-12-05 15:50 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-28  3:54 [PATCH v5 00/12] iommu/vt-d: Add scalable mode support Lu Baolu
     [not found] ` <20181128035449.10226-1-baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-28  3:54   ` [PATCH v5 01/12] iommu/vt-d: Enumerate the scalable mode capability Lu Baolu
2018-11-28  3:54   ` [PATCH v5 03/12] iommu/vt-d: Move page table helpers into header Lu Baolu
2018-11-28  3:54 ` [PATCH v5 02/12] iommu/vt-d: Manage scalalble mode PASID tables Lu Baolu
2018-12-03 13:44   ` Joerg Roedel
     [not found]     ` <20181203134411.lejlkbnagxml54ro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-03 17:23       ` Liu, Yi L
2018-12-04  5:58         ` Lu Baolu
     [not found]           ` <5c81008b-30e8-177d-0182-db366608562f-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-12-05 15:50             ` Joerg Roedel [this message]
2018-12-06  1:13               ` Lu Baolu
2018-12-05 15:47         ` Joerg Roedel
2018-11-28  3:54 ` [PATCH v5 04/12] iommu/vt-d: Add 256-bit invalidation descriptor support Lu Baolu
2018-12-03 13:48   ` Joerg Roedel
2018-12-03 17:23     ` Liu, Yi L
     [not found]       ` <A2975661238FB949B60364EF0F2C257439D838AB-0J0gbvR4kTg/UvCtAeCM4rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-04  6:13         ` Lu Baolu
2018-12-05 15:56           ` Joerg Roedel
2018-12-06  1:19             ` Lu Baolu
2018-11-28  3:54 ` [PATCH v5 05/12] iommu/vt-d: Reserve a domain id for FL and PT modes Lu Baolu
2018-11-28  3:54 ` [PATCH v5 06/12] iommu/vt-d: Add second level page table interface Lu Baolu
2018-11-28  3:54 ` [PATCH v5 07/12] iommu/vt-d: Setup pasid entry for RID2PASID support Lu Baolu
2018-11-28  3:54 ` [PATCH v5 08/12] iommu/vt-d: Pass pasid table to context mapping Lu Baolu
2018-11-28  3:54 ` [PATCH v5 09/12] iommu/vt-d: Setup context and enable RID2PASID support Lu Baolu
2018-11-28  3:54 ` [PATCH v5 10/12] iommu/vt-d: Add first level page table interface Lu Baolu
2018-11-28  3:54 ` [PATCH v5 11/12] iommu/vt-d: Shared virtual address in scalable mode Lu Baolu
2018-11-28  3:54 ` [PATCH v5 12/12] iommu/vt-d: Remove deferred invalidation Lu Baolu

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