lkml.org 
[lkml]   [2009]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [RFC patch] init default dma_ops to prepare intel_iommu_init failure
From
On Wed, 12 Aug 2009 11:17:22 -0700
Fenghua Yu <fenghua.yu@intel.com> wrote:

> > Hi there,
> >
> > On ia64 platform with dmar table and new upstream
> > kernel(config_dmar_default_on enabled),
> > if intel_iommu_init ends up without dma_ops initialized or other iommu
> > failures.
> > We got nothing to fall back. The following patch fixes it.
> >
> x86/x86-64 also needs this fix. Please check the pci_swiotlb_init for x86/64.

x86 falls back into nommu_dam_ops (though it would be better to use
swiotlb on x86_64).


> > Please review. If make sense, please apply.
> >
> > **The patch is enclosed in text attachment*
> > **Using web client to send the patch* *
> > **below is for review, please apply attached patch*/
> >
> > Thanks,
> > Luming
> >
> > Signed-off-by: Yu Luming <luming.yu@intel.com>
> >
> > arch/ia64/kernel/pci-swiotlb.c | 14 ++++++--------
> > 1 file changed, 6 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/ia64/kernel/pci-swiotlb.c b/arch/ia64/kernel/pci-swiotlb.c
> > index 223abb1..d5dcaf5 100644
> > --- a/arch/ia64/kernel/pci-swiotlb.c
> > +++ b/arch/ia64/kernel/pci-swiotlb.c
> > @@ -46,15 +46,13 @@ void __init swiotlb_dma_init(void)
> >
> > void __init pci_swiotlb_init(void)
> > {
> > - if (!iommu_detected || iommu_pass_through) {
>
> This check can not be removed. Otherwise, swiotlb_dma_ops will always override
> previous dma_ops value.

Yeah.


> I think you can change this check to something like:
> if (!dma_ops || iommu_pass_through) {

I don't think this work since pci_iommu_alloc() always sets up dma_ops
and calls pci_swiotlb_init().

All we need to do here is calling swiotlb_init() then we can use
swiotlb_dma_ops after intel_iommu_init() fails:

http://marc.info/?l=linux-kernel&m=125013354518721&w=2


> With this change, checking iommu_detected is unnecesary because checking dma_ops
> covers it.
>
> > #ifdef CONFIG_IA64_GENERIC
> > - swiotlb = 1;
> > - printk(KERN_INFO "PCI-DMA: Re-initialize machine vector.\n");
> > - machvec_init("dig");
> > - swiotlb_init();
> > - dma_ops = &swiotlb_dma_ops;
> > + swiotlb = 1;
> > + printk(KERN_INFO "PCI-DMA: Re-initialize machine vector.\n");
> > + machvec_init("dig");
> > + swiotlb_init();
> > + dma_ops = &swiotlb_dma_ops;
> > #else
> > - panic("Unable to find Intel IOMMU");
> > + panic("Unable to find Intel IOMMU");
> > #endif
> > - }
> > }
>
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/


\
 
 \ /
  Last update: 2009-08-13 06:53    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site