Re: [PATCH 04/13] iommu coherency

[Mark McLoughlin <markmc@redhat.com>]

On Tue, 2008-12-02 at 22:22 +0800, Han, Weidong wrote:

> in dmar_domain, more than one iommus may be included in iommu_bmp. Due
> to "Coherency" capability may be different across iommus, set this
> variable to indicate iommu access is coherent or not. Only when all
> related iommus in a dmar_domain are all coherent, iommu access of this
> domain is coherent.
> 
> Signed-off-by: Weidong Han <weidong.han@intel.com>
> ---
>  drivers/pci/intel-iommu.c     |    6 ++++++
>  include/linux/dma_remapping.h |    2 ++
>  2 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
> index a18e0b4..fa1507b 100644
> --- a/drivers/pci/intel-iommu.c
> +++ b/drivers/pci/intel-iommu.c
> @@ -982,6 +982,12 @@ static struct dmar_domain * iommu_alloc_domain(struct intel_iommu *iommu)
>  	domain->id = num;
>  	memset(&domain->iommu_bmp, 0, sizeof(unsigned long));
>  	set_bit(iommu->seq_id, &domain->iommu_bmp);
> +
> +	if (ecap_coherent(iommu->ecap))
> +		domain->iommu_coherency = 1;
> +	else
> +		domain->iommu_coherency = 0;

If you allocate a non-coherent iommu, followed by a coherent iommu, then
iommu_coherency ends up as 1

In patch 6/13 you add domain_update_iommu_coherency(). It would make
more sense to add that function in this patch and use it here.

Cheers,
Mark.