On Thu, Jul 01, 2010 at 05:24:32PM -0400, Tom Lyon wrote:
> This patch allows IOMMU users to determine whether the hardware and software
> support safe, isolated interrupt remapping. Not all Intel IOMMUs have the
> hardware, and the software for AMD is not there yet.
> Signed-off-by: Tom Lyon <pugs@xxxxxxxxx>
It does not make a lot of sense to check for this feature in the
IOMMU-API currently because there is no support for intr-remapping in
there. But it will be there when intr-remapping support for AMD IOMMU is
implemented. So this change can be considered as a first step in that
direction. Please repost with the change requested below an I'll add
this one to my tree.
> Version 2: previous ifdefs not needed.
>
> MST has convinced me that any user level driver for PCI master devices can't
> be safe unless there is an IOMMU protecting the APIC MSI/MSI-X interrupt
> addresses from device writes. This interrupt remapping is not present in all
> Intel IOMMUs and the code for the interrupt mapping in the AMD IOMMUs is not
> implemented yet.
>
> Needed by not-yet-accepted VFIO driver.
>
> diff -uprN linux-2.6.34/drivers/pci/intel-iommu.c iommuapi-linux-2.6.34/drivers/pci/intel-iommu.c
> --- linux-2.6.34/drivers/pci/intel-iommu.c 2010-05-16 14:17:36.000000000 -0700
> +++ iommuapi-linux-2.6.34/drivers/pci/intel-iommu.c 2010-06-30 15:47:10.000000000 -0700
> @@ -3705,6 +3705,10 @@ static int intel_iommu_domain_has_cap(st
>
> if (cap == IOMMU_CAP_CACHE_COHERENCY)
> return dmar_domain->iommu_snooping;
> + if (cap == IOMMU_CAP_SAFE_INTR_REMAP)
> + return intr_remapping_enabled;
>
> return 0;
> }
> diff -uprN linux-2.6.34/include/linux/iommu.h iommuapi-linux-2.6.34/include/linux/iommu.h
> --- linux-2.6.34/include/linux/iommu.h 2010-05-16 14:17:36.000000000 -0700
> +++ iommuapi-linux-2.6.34/include/linux/iommu.h 2010-06-30 15:47:34.000000000 -0700
> @@ -30,6 +30,7 @@ struct iommu_domain {
> };
>
> #define IOMMU_CAP_CACHE_COHERENCY 0x1
> +#define IOMMU_CAP_SAFE_INTR_REMAP 0x2 /* isolates device intrs */
I think the SAFE_ is not necessary in the name. It is misleading because
it indicates that there is an unsafe variant of intr-remapping available
when this capability is not set. Just call it IOMMU_CAP_INTR_REMAPPING.
Joerg
--
Joerg Roedel - AMD Operating System Research Center
Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632
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