As a mechanism to detect whether SWIOTLB is enabled or not.
We also fix the spelling - it was swioltb instead of
swiotlb.

CC: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
[v1: Ripped out swiotlb_enabled]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Things like THIS_MODULE and EXPORT_SYMBOL were simply everywhere
because module.h was also everywhere.  But we are fixing the latter.
So we need to call out the real users in advance.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

The process to swizzle a Machine Frame Number (MFN) is not always
necessary. Especially if we know that we actually do not have to do it.
In this patch we check the MFN against the device's coherent
DMA mask and if the requested page(s) are contingous. If it all checks
out we will just return the bus addr without doing the memory
swizzle.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Fix printk() and panic() args [swap them] to fix build warnings:

drivers/xen/swiotlb-xen.c:201: warning: format '%s' expects type 'char *', but argument 2 has type 'int'
drivers/xen/swiotlb-xen.c:201: warning: format '%d' expects type 'int', but argument 3 has type 'char *'
drivers/xen/swiotlb-xen.c:202: warning: format '%s' expects type 'char *', but argument 2 has type 'int'
drivers/xen/swiotlb-xen.c:202: warning: format '%d' expects type 'int', but argument 3 has type 'char *'
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Propagate the baremetal git commit "swiotlb: fix wrong panic"
(fba99fa3) in the Xen-SWIOTLB version.
wherein swiotlb's map_page wrongly calls panic() when it can't find
a buffer fit for device's dma mask.  It should return an error instead.

Devices with an odd dma mask (i.e.  under 4G) like b44 network card hit
this bug (the system crashes):

http://marc.info/?l=linux-kernel&m=129648943830106&w=2

If xen-swiotlb returns an error, b44 driver can use the own bouncing
mechanism.

CC: stable@kernel.org
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We can fail seting up Xen-SWIOTLB if:
 - The host does not have enough contiguous DMA32 memory available
   (can happen on a machine that has fragmented memory from starting,
   stopping many guests).
 - Not enough low memory (almost never happens).

We retry allocating and exchanging the swath of contiguous memory
up to three times. Each time we decrease the amount we need  - the
minimum being of 2MB.

If we compleltly fail, we will print the reason for failure on the Xen
console on top of doing it to earlyprintk=xen console.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

By default the io_tlb_nslabs is set to zero, and gets set to
whatever value is passed in via swiotlb_init_with_tbl function.
The default value passed in is 64MB. However, if the user provides
the 'swiotlb=<nslabs>' the default value is ignored and
the value provided by the user is used... Except when the SWIOTLB
is used under Xen - there the default value of 64MB is used and
the Xen-SWIOTLB has no mechanism to get the 'io_tlb_nslabs' filled
out by setup_io_tlb_npages functions. This patch provides a function
for the Xen-SWIOTLB to call to see if the io_tlb_nslabs is set
and if so use that value.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NJustin P. Mattock <justinmattock@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This patchset:

PV guests under Xen are running in an non-contiguous memory architecture.

When PCI pass-through is utilized, this necessitates an IOMMU for
translating bus (DMA) to virtual and vice-versa and also providing a
mechanism to have contiguous pages for device drivers operations (say DMA
operations).

Specifically, under Xen the Linux idea of pages is an illusion. It
assumes that pages start at zero and go up to the available memory. To
help with that, the Linux Xen MMU provides a lookup mechanism to
translate the page frame numbers (PFN) to machine frame numbers (MFN)
and vice-versa. The MFN are the "real" frame numbers. Furthermore
memory is not contiguous. Xen hypervisor stitches memory for guests
from different pools, which means there is no guarantee that PFN==MFN
and PFN+1==MFN+1. Lastly with Xen 4.0, pages (in debug mode) are
allocated in descending order (high to low), meaning the guest might
never get any MFN's under the 4GB mark.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Albert Herranz <albert_herranz@yahoo.es>
Cc: Ian Campbell <Ian.Campbell@citrix.com>