From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: [PATCH V2] 2.6.34: simple IOMMU API extension to check safe interrupt remapping Date: Fri, 2 Jul 2010 11:26:46 +0200 Message-ID: <20100702092646.GF24084@amd.com> References: <4c2d0790.Bi9FugC8c/QW1Ike%pugs@cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "chrisw@sous-sol.org" , "mst@redhat.com" , "dwmw2@infradead.org" , "aafabbri@cisco.com" , "scofeldm@cisco.com" To: Tom Lyon Return-path: Content-Disposition: inline In-Reply-To: <4c2d0790.Bi9FugC8c/QW1Ike%pugs@cisco.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 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