From: David Woodhouse <dwmw2@infradead.org>
To: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>, Yinghai Lu <yinghai@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Dan Williams <dan.j.williams@intel.com>,
Vinod Koul <vinod.koul@intel.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Tony Luck <tony.luck@intel.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
dmaengine@vger.kernel.org, iommu@lists.linux-foundation.org
Subject: Re: [Patch Part2 V2 15/17] iommu/vt-d, PCI: update DRHD/RMRR/ATSR device scope caches when PCI hotplug happens
Date: Thu, 06 Mar 2014 18:25:19 +0000 [thread overview]
Message-ID: <1394130319.9994.28.camel@i7.infradead.org> (raw)
In-Reply-To: <1392790057-32434-16-git-send-email-jiang.liu@linux.intel.com>
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On Wed, 2014-02-19 at 14:07 +0800, Jiang Liu wrote:
> Current Intel DMAR/IOMMU driver assumes that all PCI devices
> associated
> with DMAR/RMRR/ATSR device scope arrays are created at boot time and
> won't change at runtime, so it caches pointers of associated PCI
> device
> object. That assumption may be wrong now due to:
> 1) introduction of PCI host bridge hotplug
> 2) PCI device hotplug through sysfs interfaces.
...
> This patch introduces a new mechanism to update the DRHD/RMRR/ATSR
> device scope caches by hooking PCI bus notification.
Hm, this seems overly complex. Can't we just abandon the
dmaru->devices[] array completely? In dmar_find_matched_drhd_unit()
can't we just compare the path in the scope entries directly to the PCI
device we are trying to find a DRHD for?
We then cache the result in dev->archdata.iommu for ever (well, until
hot-unplug) anyway, so it shouldn't even be any less efficient to do it
on demand, right?
That's true at least for dmar_find_matched_drhd_unit(). Perhaps we'd
need to find a way to cache the result for
dmar_find_matched_atsr_unit()?
--
dwmw2
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next prev parent reply other threads:[~2014-03-06 18:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-19 6:07 [Patch Part2 V2 00/17] Enhance DMAR drivers to handle PCI/memory hotplug events Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 01/17] iommu/vt-d: avoid double free of g_iommus on error recovery path Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 02/17] iommu/vt-d: avoid caching stale domain_device_info and fix memory leak Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 03/17] iommu/vt-d: avoid caching stale domain_device_info when hot-removing PCI device Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 04/17] iommu/vt-d: factor out dmar_alloc_dev_scope() for later reuse Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 05/17] iommu/vt-d: move private structures and variables into intel-iommu.c Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 06/17] iommu/vt-d: simplify function get_domain_for_dev() Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 07/17] iommu/vt-d: free resources if failed to create domain for PCIe endpoint Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 08/17] iommu/vt-d: reduce duplicated code to handle virtual machine domains Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 09/17] iommu/vt-d: fix incorrect iommu_count for si_domain Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 10/17] iommu/vt-d: check for NULL pointer when freeing IOMMU data structure Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 11/17] iommu/vt-d: fix error in detect ATS capability Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 12/17] iommu/vt-d: introduce macro for_each_dev_scope() to walk device scope entries Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 13/17] iommu/vt-d: introduce a rwsem to protect global data structures Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 14/17] iommu/vt-d: use RCU to protect global resources in interrupt context Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 15/17] iommu/vt-d, PCI: update DRHD/RMRR/ATSR device scope caches when PCI hotplug happens Jiang Liu
2014-03-06 18:25 ` David Woodhouse [this message]
2014-03-10 8:46 ` Jiang Liu
2014-03-10 13:04 ` David Woodhouse
2014-02-19 6:07 ` [Patch Part2 V2 16/17] iommu/vt-d, PCI: unify the way to process DMAR device scope array Jiang Liu
2014-02-19 6:07 ` [Patch Part2 V2 17/17] iommu/vt-d: update IOMMU state when memory hotplug happens Jiang Liu
2014-03-05 7:48 ` [Patch Part2 V2 00/17] Enhance DMAR drivers to handle PCI/memory hotplug events Joerg Roedel
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