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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	iommu@lists.linux-foundation.org,
	LKML <linux-kernel@vger.kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Yi Liu <yi.l.liu@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Christoph Hellwig <hch@infradead.org>,
	Jonathan Cameron <jic23@kernel.org>,
	Eric Auger <eric.auger@redhat.com>
Subject: Re: [PATCH 07/10] iommu/ioasid: Use mutex instead of spinlock
Date: Wed, 1 Apr 2020 15:58:48 +0200	[thread overview]
Message-ID: <20200401135848.GH882512@myrica> (raw)
In-Reply-To: <1585158931-1825-8-git-send-email-jacob.jun.pan@linux.intel.com>

On Wed, Mar 25, 2020 at 10:55:28AM -0700, Jacob Pan wrote:
> Each IOASID or set could have multiple users with its own HW context
> to maintain. Often times access to the HW context requires thread context.
> For example, consumers of IOASIDs can register notification blocks to
> sync up its states. Having an atomic notifier is not feasible for these
> update operations.
> 
> This patch converts allocator lock from spinlock to mutex in preparation
> for IOASID notifier.

Unfortunately this doesn't work for SVA, which needs to call ioasid_free()
from the RCU callback of mmu_notifier_put(), which cannot sleep. We're
relying on MMU notifers this way to ensure that there is a single IOASID
per mm.

Thanks,
Jean

WARNING: multiple messages have this Message-ID (diff)
From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org,
	Alex Williamson <alex.williamson@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH 07/10] iommu/ioasid: Use mutex instead of spinlock
Date: Wed, 1 Apr 2020 15:58:48 +0200	[thread overview]
Message-ID: <20200401135848.GH882512@myrica> (raw)
In-Reply-To: <1585158931-1825-8-git-send-email-jacob.jun.pan@linux.intel.com>

On Wed, Mar 25, 2020 at 10:55:28AM -0700, Jacob Pan wrote:
> Each IOASID or set could have multiple users with its own HW context
> to maintain. Often times access to the HW context requires thread context.
> For example, consumers of IOASIDs can register notification blocks to
> sync up its states. Having an atomic notifier is not feasible for these
> update operations.
> 
> This patch converts allocator lock from spinlock to mutex in preparation
> for IOASID notifier.

Unfortunately this doesn't work for SVA, which needs to call ioasid_free()
from the RCU callback of mmu_notifier_put(), which cannot sleep. We're
relying on MMU notifers this way to ensure that there is a single IOASID
per mm.

Thanks,
Jean
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  parent reply	other threads:[~2020-04-01 13:59 UTC|newest]

Thread overview: 114+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 17:55 [PATCH 00/10] IOASID extensions for guest SVA Jacob Pan
2020-03-25 17:55 ` Jacob Pan
2020-03-25 17:55 ` [PATCH 01/10] iommu/ioasid: Introduce system-wide capacity Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  8:07   ` Tian, Kevin
2020-03-27  8:07     ` Tian, Kevin
2020-03-27 16:08     ` Jacob Pan
2020-03-27 16:08       ` Jacob Pan
2020-04-01 13:45   ` Jean-Philippe Brucker
2020-04-01 13:45     ` Jean-Philippe Brucker
2020-04-01 22:50     ` Jacob Pan
2020-04-01 22:50       ` Jacob Pan
2020-03-25 17:55 ` [PATCH 02/10] iommu/vt-d: Set IOASID capacity when SVM is enabled Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  8:08   ` Tian, Kevin
2020-03-27  8:08     ` Tian, Kevin
2020-03-25 17:55 ` [PATCH 03/10] iommu/ioasid: Introduce per set allocation APIs Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-26  2:12   ` Lu Baolu
2020-03-26  2:12     ` Lu Baolu
2020-03-26 21:30     ` Jacob Pan
2020-03-26 21:30       ` Jacob Pan
2020-03-27  8:38   ` Tian, Kevin
2020-03-27  8:38     ` Tian, Kevin
2020-03-27 16:59     ` Jacob Pan
2020-03-27 16:59       ` Jacob Pan
2020-03-28  6:32       ` Tian, Kevin
2020-03-28  6:32         ` Tian, Kevin
2020-04-01 13:47   ` Jean-Philippe Brucker
2020-04-01 13:47     ` Jean-Philippe Brucker
2020-04-06 20:02     ` Jacob Pan
2020-04-06 20:02       ` Jacob Pan
2020-04-07 11:01       ` Jean-Philippe Brucker
2020-04-07 11:01         ` Jean-Philippe Brucker
2020-04-21 21:51         ` Jacob Pan
2020-04-21 21:51           ` Jacob Pan
2020-03-25 17:55 ` [PATCH 04/10] iommu/ioasid: Rename ioasid_set_data to avoid confusion with ioasid_set Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  9:35   ` Tian, Kevin
2020-03-27  9:35     ` Tian, Kevin
2020-03-25 17:55 ` [PATCH 05/10] iommu/ioasid: Create an IOASID set for host SVA use Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  9:41   ` Tian, Kevin
2020-03-27  9:41     ` Tian, Kevin
2020-03-27 17:28     ` Jacob Pan
2020-03-27 17:28       ` Jacob Pan
2020-03-28  6:33       ` Tian, Kevin
2020-03-28  6:33         ` Tian, Kevin
2020-04-01 13:53   ` Jean-Philippe Brucker
2020-04-01 13:53     ` Jean-Philippe Brucker
2020-04-06 15:33     ` Jacob Pan
2020-04-06 15:33       ` Jacob Pan
2020-04-07 11:01       ` Jean-Philippe Brucker
2020-04-07 11:01         ` Jean-Philippe Brucker
2020-04-13 22:06         ` Jacob Pan
2020-04-13 22:06           ` Jacob Pan
2020-04-15 15:10           ` Jean-Philippe Brucker
2020-04-15 15:10             ` Jean-Philippe Brucker
2020-03-25 17:55 ` [PATCH 06/10] iommu/ioasid: Convert to set aware allocations Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  9:54   ` Tian, Kevin
2020-03-27  9:54     ` Tian, Kevin
2020-03-27 17:41     ` Jacob Pan
2020-03-27 17:41       ` Jacob Pan
2020-03-28  6:40       ` Tian, Kevin
2020-03-28  6:40         ` Tian, Kevin
2020-04-06 20:07         ` Jacob Pan
2020-04-06 20:07           ` Jacob Pan
2020-04-01 13:55   ` Jean-Philippe Brucker
2020-04-01 13:55     ` Jean-Philippe Brucker
2020-04-01 22:45     ` Jacob Pan
2020-04-01 22:45       ` Jacob Pan
2020-03-25 17:55 ` [PATCH 07/10] iommu/ioasid: Use mutex instead of spinlock Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27  9:55   ` Tian, Kevin
2020-03-27  9:55     ` Tian, Kevin
2020-04-01 13:58   ` Jean-Philippe Brucker [this message]
2020-04-01 13:58     ` Jean-Philippe Brucker
2020-03-25 17:55 ` [PATCH 08/10] iommu/ioasid: Introduce notifier APIs Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27 10:03   ` Tian, Kevin
2020-03-27 10:03     ` Tian, Kevin
2020-03-27 18:36     ` Jacob Pan
2020-03-27 18:36       ` Jacob Pan
2020-03-28  6:43       ` Tian, Kevin
2020-03-28  6:43         ` Tian, Kevin
2020-03-31 15:13         ` Jacob Pan
2020-03-31 15:13           ` Jacob Pan
2020-04-01 14:00   ` Jean-Philippe Brucker
2020-04-01 14:00     ` Jean-Philippe Brucker
2020-04-10 15:43     ` Jacob Pan
2020-04-10 15:43       ` Jacob Pan
2020-03-25 17:55 ` [PATCH 09/10] iommu/ioasid: Support ioasid_set quota adjustment Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27 10:09   ` Tian, Kevin
2020-03-27 10:09     ` Tian, Kevin
2020-03-27 23:30     ` Jacob Pan
2020-03-27 23:30       ` Jacob Pan
2020-03-28  6:44       ` Tian, Kevin
2020-03-28  6:44         ` Tian, Kevin
2020-03-25 17:55 ` [PATCH 10/10] iommu/vt-d: Register PASID notifier for status change Jacob Pan
2020-03-25 17:55   ` Jacob Pan
2020-03-27 10:22   ` Tian, Kevin
2020-03-27 10:22     ` Tian, Kevin
2020-03-27 23:47     ` Jacob Pan
2020-03-27 23:47       ` Jacob Pan
2020-04-01 14:03 ` [PATCH 00/10] IOASID extensions for guest SVA Jean-Philippe Brucker
2020-04-01 14:03   ` Jean-Philippe Brucker
2020-04-01 23:38   ` Jacob Pan
2020-04-01 23:38     ` Jacob Pan
2020-04-02 12:26     ` Jean-Philippe Brucker
2020-04-02 12:26       ` Jean-Philippe Brucker
2020-04-02 16:09       ` Jacob Pan
2020-04-02 16:09         ` Jacob Pan

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