Messages in this thread | | | Date | Tue, 11 Sep 2007 10:22:57 -0700 | From | "Keshavamurthy, Anil S" <> | Subject | Re: [RFC][Intel-IOMMU] Fix for IOMMU early crash |
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On Sun, Sep 09, 2007 at 08:51:40PM +0300, Muli Ben-Yehuda wrote: > On Mon, Sep 10, 2007 at 08:43:59AM -0700, Keshavamurthy, Anil S wrote: > > On Sun, Sep 09, 2007 at 02:16:19PM +0300, Muli Ben-Yehuda wrote: > > > On Sat, Sep 08, 2007 at 01:05:24PM -0700, Keshavamurthy, Anil S wrote: > > > > > > > Subject: [RFC][Intel-IOMMU] Fix for IOMMU early crash > > > > > > This patch feels like a huge hack. See below. > > > > You seem to be jumping to conclusion without going in detail. The > > pci_dev struct contains pointer to sysdata, which in turn points to > > the copy of its parent's bus sysdata. So technically speaking we > > can eliminate sysdata pointer from pci_dev struct which is what one > > portion of this patch does. > > ... provided nothing relies on this relationship or the existence of > the pci_dev's sysdata. Have you audited every architecture's use of > the sysdata pointers? > > > > > This patch removes sysdata from pci_dev struct and creates a new > > > > field called sys_data which is exclusively used by IOMMU driver to > > > > keep its per device context pointer. > > > > > > Hmpf, why is this needed? with the pci_sysdata work that recently went > > > into mainline we have a void *iommu member in pci_sysdata which should > > > be all that's needed. Please elaborate if it's not enough for your > > > needs. > > > I looked at your patch and it was not suitable because I need to > > store iommu private pointer in pci_dev > > Could you elaborate on why you need this? I'm assuming it's for the > per-device IOMMU page tables? Yes, it is for per-device IOMMU domain information which internally holds info about the page tables. > > > and not in the pci_bus. So I have added a new member sys_data in the > > pci_dev struct. I can change the name from sys_dev to iomu_priv to > > clear the confusion. Do let me know. > > Well, you should be able to just use the pci_dev's ->sysdata (that's > what it's there for after all!) but you might need to make it point to > a structure if it's shared, the same way we did with the bus's > ->sysdata. How about adding a new field as I don't care about KABI for mainline?
>I agree that just having it point to the bus's ->sysdata is > not very useful *but* there may be code in the kernel that relies on > it (Calgary did until very recently...) so it would have to be audited > first. I still wonder copying bus's->sysdata to pci_dev's-> sysdata is any useful?
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