Messages in this thread | | | Date | Fri, 2 Jul 2010 11:26:46 +0200 | From | "Roedel, Joerg" <> | Subject | Re: [PATCH V2] 2.6.34: simple IOMMU API extension to check safe interrupt remapping |
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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@cisco.com>
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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