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0444ad93ea
This patch set adds a mechanism to "modularize" the IOMMUs we have on X86. Currently the count of IOMMUs is up to six and they have a complex relationship that requires careful execution order. 'pci_iommu_alloc' does that today, but most folks are unhappy with how it does it. This patch set addresses this and also paves a mechanism to jettison unused IOMMUs during run-time. For details that sparked this, please refer to: http://lkml.org/lkml/2010/8/2/282 The first solution that comes to mind is to convert wholesale the IOMMU detection routines to be called during initcall time frame. Unfortunately that misses the dependency relationship that some of the IOMMUs have (for example: for AMD-Vi IOMMU to work, GART detection MUST run first, and before all of that SWIOTLB MUST run). The second solution would be to introduce a registration call wherein the IOMMU would provide its detection/init routines and as well on what MUST run before it. That would work, except that the 'pci_iommu_alloc' which would run through this list, is called during mem_init. This means we don't have any memory allocator, and it is so early that we haven't yet started running through the initcall_t list. This solution borrows concepts from the 2nd idea and from how MODULE_INIT works. A macro is provided that each IOMMU uses to define it's detect function and early_init (before the memory allocate is active), and as well what other IOMMU MUST run before us. Since most IOMMUs depend on having SWIOTLB run first ("pci_swiotlb_detect") a convenience macro to depends on that is also provided. This macro is similar in design to MODULE_PARAM macro wherein we setup a .iommu_table section in which we populate it with the values that match a struct iommu_table_entry. During bootup we will sort through the array so that the IOMMUs that MUST run before us are first elements in the array. And then we just iterate through them calling the detection routine and if appropiate, the init routines. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> LKML-Reference: <1282845485-8991-2-git-send-email-konrad.wilk@oracle.com> CC: H. Peter Anvin <hpa@zytor.com> CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp> CC: Thomas Gleixner <tglx@linutronix.de> CC: Ingo Molnar <mingo@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> |
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