The header comments diverged a bit from the implementation. Lets
re-sync them.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <1286564028-2352-3-git-send-email-konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
In 'pci_swiotlb_detect' we used to do two different things:
a). If user provided 'iommu=soft' or 'swiotlb=force' we
would set swiotlb=1 and return 1 (and forcing pci-dma.c
to call pci_swiotlb_init() immediately).
b). If 4GB or more would be detected and if user did not specify
iommu=off, we would set 'swiotlb=1' and return whatever 'a)'
figured out.
We simplify this by splitting a) and b) in two different routines.
CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <1282845485-8991-5-git-send-email-konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
We are using a very simple sort routine which sorts the .iommu_table
array in the order of dependencies. Specifically each structure
of iommu_table_entry has a field 'depend' which contains the function
pointer to the IOMMU that MUST be run before us. We sort the array
of structures so that the struct iommu_table_entry with no
'depend' field are first, and then the subsequent ones are the
ones for which the 'depend' function has been already invoked
(in other words, precede us).
Using the kernel's version 'sort', which is a mergeheap is
feasible, but would require making the comparison operator
scan recursivly the array to satisfy the "heapify" process: setting the
levels properly. The end result would much more complex than it should
be an it is just much simpler to utilize this simple sort routine.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <1282845485-8991-4-git-send-email-konrad.wilk@oracle.com>
CC: H. Peter Anvin <hpa@zytor.com>
CC: Fujita Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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>
Konrad Rzeszutek Wilk