linux-kernel - Re: [PATCH 9/9] x86/iommu: use dma_ops_list in get_dma

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Date:	Fri, 26 Sep 2008 13:00:04 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Amit Shah <amit.shah@...hat.com>
CC:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	iommu@...ts.linux-foundation.org,
	David Woodhouse <dwmw2@...radead.org>,
	Muli Ben-Yehuda <muli@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Subject: Re: [PATCH 9/9] x86/iommu: use dma_ops_list in get_dma_ops

On Fri, Sep 26, 2008 at 01:26:19PM +0530, Amit Shah wrote:
> * On Monday 22 Sep 2008 23:51:21 Joerg Roedel wrote:
> > This patch enables stackable dma_ops on x86. To do this, it also enables
> > the per-device dma_ops on i386.
> >
> > Signed-off-by: Joerg Roedel <joerg.roedel@....com>
> > ---
> >  arch/x86/kernel/pci-dma.c     |   26 ++++++++++++++++++++++++++
> >  include/asm-x86/device.h      |    6 +++---
> >  include/asm-x86/dma-mapping.h |   14 +++++++-------
> >  3 files changed, 36 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> > index b990fb6..2e517c2 100644
> > --- a/arch/x86/kernel/pci-dma.c
> > +++ b/arch/x86/kernel/pci-dma.c
> > @@ -82,6 +82,32 @@ void x86_register_dma_ops(struct dma_mapping_ops *ops,
> >  	write_unlock_irqrestore(&dma_ops_list_lock, flags);
> >  }
> >
> > +struct dma_mapping_ops *find_dma_ops_for_device(struct device *dev)
> > +{
> > +	int i;
> > +	unsigned long flags;
> > +	struct dma_mapping_ops *entry, *ops = NULL;
> > +
> > +	read_lock_irqsave(&dma_ops_list_lock, flags);
> > +
> > +	for (i = 0; i < DMA_OPS_TYPE_MAX; ++i)
> > +		list_for_each_entry(entry, &dma_ops_list[i], list) {
> > +			if (!entry->device_supported)
> > +				continue;
> > +			if (entry->device_supported(dev)) {
> > +				ops = entry;
> > +				goto out;
> > +			}
> > +		}
> > +out:
> > +	read_unlock_irqrestore(&dma_ops_list_lock, flags);
> 
> For PVDMA, we want the "native" dma_ops to succeed first, eg, nommu, and then 
> do our "PV DMA", which is just translating gpa  to hpa and then program the 

Btw, how will dma_masks be handled when PV DMA just translates gpa to
hpa?

Joerg

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