linux-kernel - Re: [PATCH kernel v12 17/34] powerpc/spapr: vfio: Switch from iommu_table to new iommu_table

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Message-ID: <20150609023632.GA11000@voom.redhat.com>
Date:	Tue, 9 Jun 2015 12:36:32 +1000
From:	David Gibson <david@...son.dropbear.id.au>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	Alex Williamson <alex.williamson@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Gavin Shan <gwshan@...ux.vnet.ibm.com>,
	Paul Mackerras <paulus@...ba.org>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernel v12 17/34] powerpc/spapr: vfio: Switch from
 iommu_table to new iommu_table_group

On Fri, Jun 05, 2015 at 04:35:09PM +1000, Alexey Kardashevskiy wrote:
> So far one TCE table could only be used by one IOMMU group. However
> IODA2 hardware allows programming the same TCE table address to
> multiple PE allowing sharing tables.
> 
> This replaces a single pointer to a group in a iommu_table struct
> with a linked list of groups which provides the way of invalidating
> TCE cache for every PE when an actual TCE table is updated. This adds pnv_pci_link_table_and_group() and pnv_pci_unlink_table_and_group() helpers to manage the list. However without VFIO, it is still going
> to be a single IOMMU group per iommu_table.
> 
> This changes iommu_add_device() to add a device to a first group
> from the group list of a table as it is only called from the platform
> init code or PCI bus notifier and at these moments there is only
> one group per table.
> 
> This does not change TCE invalidation code to loop through all
> attached groups in order to simplify this patch and because
> it is not really needed in most cases. IODA2 is fixed in a later
> patch.
> 
> This should cause no behavioural change.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
> [aw: for the vfio related changes]
> Acked-by: Alex Williamson <alex.williamson@...hat.com>
> Reviewed-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>

Reviewed-by: David Gibson <david@...son.dropbear.id.au>

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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