io-mapping: Cleanup atomic iomap

Switch the atomic iomap implementation over to kmap_local and stick the
preempt/pagefault mechanics into the generic code similar to the
kmap_atomic variants.

Rename the x86 map function in preparation for a non-atomic variant.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095858.625310005@linutronix.de

x86/mm/highmem: Use generic kmap atomic implementation

Convert X86 to the generic kmap atomic implementation and make the
iomap_atomic() naming convention consistent while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201103095857.375127260@linutronix.de

x86/mm/pat: Rename <asm/pat.h> => <asm/memtype.h>

pat.h is a file whose main purpose is to provide the memtype_*() APIs.

PAT is the low level hardware mechanism - but the high level abstraction
is memtype.

So name the header <memtype.h> as well - this goes hand in hand with memtype.c
and memtype_interval.c.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/mm/pat: Standardize on memtype_*() prefix for APIs

Half of our memtype APIs are memtype_ prefixed, the other half are _memtype suffixed:

reserve_memtype()
free_memtype()
kernel_map_sync_memtype()
io_reserve_memtype()
io_free_memtype()

memtype_check_insert()
memtype_erase()
memtype_lookup()
memtype_copy_nth_element()

Use prefixes consistently, like most other modern kernel APIs:

reserve_memtype() => memtype_reserve()
free_memtype() => memtype_free()
kernel_map_sync_memtype() => memtype_kernel_map_sync()
io_reserve_memtype() => memtype_reserve_io()
io_free_memtype() => memtype_free_io()

memtype_check_insert() => memtype_check_insert()
memtype_erase() => memtype_erase()
memtype_lookup() => memtype_lookup()
memtype_copy_nth_element() => memtype_copy_nth_element()

Signed-off-by: Ingo Molnar <mingo@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86/mm: Do not auto-massage page protections

A PTE is constructed from a physical address and a pgprotval_t.
__PAGE_KERNEL, for instance, is a pgprot_t and must be converted
into a pgprotval_t before it can be used to create a PTE. This is
done implicitly within functions like pfn_pte() by massage_pgprot().

However, this makes it very challenging to set bits (and keep them
set) if your bit is being filtered out by massage_pgprot().

This moves the bit filtering out of pfn_pte() and friends. For
users of PAGE_KERNEL*, filtering will be done automatically inside
those macros but for users of __PAGE_KERNEL*, they need to do their
own filtering now.

Note that we also just move pfn_pte/pmd/pud() over to check_pgprot()
instead of massage_pgprot(). This way, we still *look* for
unsupported bits and properly warn about them if we find them. This
might happen if an unfiltered __PAGE_KERNEL* value was passed in,
for instance.

- printk format warning fix from: Arnd Bergmann <arnd@arndb.de>
- boot crash fix from: Tom Lendacky <thomas.lendacky@amd.com>
- crash bisected by: Mike Galbraith <efault@gmx.de>

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-and-fixed-by: Arnd Bergmann <arnd@arndb.de>
Fixed-by: Tom Lendacky <thomas.lendacky@amd.com>
Bisected-by: Mike Galbraith <efault@gmx.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205509.77E1D7F6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/mm: Audit and remove any unnecessary uses of module.h

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig. The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance
for the presence of either and replace accordingly where needed.

Note that some bool/obj-y instances remain since module.h is
the header for some exception table entry stuff, and for things
like __init_or_module (code that is tossed when MODULES=n).

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-3-paul.gortmaker@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/mm/pat: Remove pat_enabled() checks

Now that we emulate a PAT table when PAT is disabled, there's no
need for those checks anymore as the PAT abstraction will handle
those cases too.

Based on a conglomerate patch from Toshi Kani.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Elliott@hp.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arnd@arndb.de
Cc: hch@lst.de
Cc: hmh@hmh.eng.br
Cc: jgross@suse.com
Cc: konrad.wilk@oracle.com
Cc: linux-mm <linux-mm@kvack.org>
Cc: linux-nvdimm@lists.01.org
Cc: stefan.bader@canonical.com
Cc: yigal@plexistor.com
Link: http://lkml.kernel.org/r/1433436928-31903-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/mm/pat: Wrap pat_enabled into a function API

We use pat_enabled in x86-specific code to see if PAT is enabled
or not but we're granting full access to it even though readers
do not need to set it. If, for instance, we granted access to it
to modules later they then could override the variable
setting... no bueno.

This renames pat_enabled to a new static variable __pat_enabled.
Folks are redirected to use pat_enabled() now.

Code that sets this can only be internal to pat.c. Apart from
the early kernel parameter "nopat" to disable PAT, we also have
a few cases that disable it later and make use of a helper
pat_disable(). It is wrapped under an ifdef but since that code
cannot run unless PAT was enabled its not required to wrap it
with ifdefs, unwrap that. Likewise, since "nopat" doesn't really
change non-PAT systems just remove that ifdef as well.

Although we could add and use an early_param_off(), these
helpers don't use __read_mostly but we want to keep
__read_mostly for __pat_enabled as this is a hot path -- upon
boot, for instance, a simple guest may see ~4k accesses to
pat_enabled(). Since __read_mostly early boot params are not
that common we don't add a helper for them just yet.

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Walls <awalls@md.metrocast.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kyle McMartin <kyle@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1430425520-22275-3-git-send-email-mcgrof@do-not-panic.com
Link: http://lkml.kernel.org/r/1432628901-18044-13-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/preempt, mm/kmap: Explicitly disable/enable preemption in kmap_atomic_*

The existing code relies on pagefault_disable() implicitly disabling
preemption, so that no schedule will happen between kmap_atomic() and
kunmap_atomic().

Let's make this explicit, to prepare for pagefault_disable() not
touching preemption anymore.

Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-5-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86: Use new cache mode type in mm/iomap_32.c

Instead of directly using the cache mode bits in the pte switch to
using the cache mode type. This requires to change
io_reserve_memtype() as well.

Based-on-patch-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stefan.bader@canonical.com
Cc: xen-devel@lists.xensource.com
Cc: konrad.wilk@oracle.com
Cc: ville.syrjala@linux.intel.com
Cc: david.vrabel@citrix.com
Cc: jbeulich@suse.com
Cc: toshi.kani@hp.com
Cc: plagnioj@jcrosoft.com
Cc: tomi.valkeinen@ti.com
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1415019724-4317-9-git-send-email-jgross@suse.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

mm: fix race in kunmap_atomic()

Christoph reported a nice splat which illustrated a race in the new stack
based kmap_atomic implementation.

The problem is that we pop our stack slot before we're completely done
resetting its state -- in particular clearing the PTE (sometimes that's
CONFIG_DEBUG_HIGHMEM). If an interrupt happens before we actually clear
the PTE used for the last slot, that interrupt can reuse the slot in a
dirty state, which triggers a BUG in kmap_atomic().

Fix this by introducing kmap_atomic_idx() which reports the current slot
index without actually releasing it and use that to find the PTE and delay
the _pop() until after we're completely done.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: stack based kmap_atomic()

Keep the current interface but ignore the KM_type and use a stack based
approach.

The advantage is that we get rid of crappy code like:

#define __KM_PTE \
(in_nmi() ? KM_NMI_PTE : \
in_irq() ? KM_IRQ_PTE : \
KM_PTE0)

and in general can stop worrying about what context we're in and what kmap
slots might be appropriate for that.

The downside is that FRV kmap_atomic() gets more expensive.

For now we use a CPP trick suggested by Andrew:

#define kmap_atomic(page, args...) __kmap_atomic(page)

to avoid having to touch all kmap_atomic() users in a single patch.

[ not compiled on:
- mn10300: the arch doesn't actually build with highmem to begin with ]

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c]
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: Fix the address space annotations of iomap_atomic_prot_pfn()

This patch fixes the sparse warnings when the return pointer of
iomap_atomic_prot_pfn() is used as an argument of iowrite32()
and friends.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
LKML-Reference: <1283633804-11749-1-git-send-email-currojerez@riseup.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86, pat: Add PAT reserve free to io_mapping* APIs

io_mapping_* interfaces were added, mainly for graphics drivers.
Make this interface go through the PAT reserve/free, instead of
hardcoding WC mapping. This makes sure that there are no
aliases due to unconditional WC setting.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

mm: fix misuse of debug_kmap_atomic

Commit 7ca43e7564679604d86e9ed834e7bbcffd8a4a3f ("mm: use debug_kmap_atomic")
introduced some debug_kmap_atomic() in wrong places.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86: fix is_io_mapping_possible() build warning on i386 allnoconfig

i386 allnoconfig:

arch/x86/mm/iomap_32.c: In function 'is_io_mapping_possible':
arch/x86/mm/iomap_32.c:27: warning: comparison is always false due to limited range of data type

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86, mm: fix misuse of debug_kmap_atomic

Impact: fix CONFIG_DEBUG_HIGHMEM=y breakage

Commit 7ca43e756 ("mm: use debug_kmap_atomic") introduced some
debug_kmap_atomic() calls in the wrong places.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090402070126.GA3951@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

mm: use debug_kmap_atomic

Use debug_kmap_atomic in kmap_atomic, kmap_atomic_pfn, and
iomap_atomic_prot_pfn.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

x86/paravirt: remove lazy mode in interrupts

Impact: simplification, robustness

Make paravirt_lazy_mode() always return PARAVIRT_LAZY_NONE
when in an interrupt. This prevents interrupt code from
accidentally inheriting an outer lazy state, and instead
does everything synchronously. Outer batched operations
are left deferred.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>

x86, mm: remove unnecessary include file from iomap_32.c

asm/highmem.h inclusion is added to use kmap_atomic_prot_pfn()
by commit bb6d59ca927d855ffac567b35c0a790c67016103

Now kmap_atomic_prot_pfn is moved to iomap_32.c
by commit dd63fdcc63f0f853b116b52e56200a0e0227cf5f

So the asm/highmem.h inclusion in iomap_32.c is unnecessary now.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090315151517.GA29074@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: unify kmap_atomic_pfn() and iomap_atomic_prot_pfn(), fix

Impact: build fix

Move kmap_atomic_prot_pfn() to iomap_32.c. It is used on all 32-bit
kernels, while highmem_32.c is only built on highmem kernels.

( Note: the debug_kmap_atomic_prot() check is removed for now, that
problem is handled via another patch. )

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090311143317.GA22244@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: unify kmap_atomic_pfn() and iomap_atomic_prot_pfn()

kmap_atomic_pfn() and iomap_atomic_prot_pfn() are almost same
except pgprot. This patch removes the code duplication for these
two functions.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090311143317.GA22244@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Revert "gpu/drm, x86, PAT: PAT support for io_mapping_*"

This reverts commit 17581ad812a9abb0182260374ef2e52d4a808a64.

Sitsofe Wheeler reported that /dev/dri/card0 is MIA on his EeePC 900
and bisected it to this commit.

Graphics card is an i915 in an EeePC 900:

00:02.0 VGA compatible controller [0300]:
Intel Corporation Mobile 915GM/GMS/910GML
Express Graphics Controller [8086:2592] (rev 04)

( Most likely the ioremap() of the driver failed and hence the card
did not initialize. )

Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Bisected-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: i915 needs pgprot_writecombine() and is_io_mapping_possible()

Impact: build fix

Theodore Ts reported that the i915 driver needs these symbols:

ERROR: "pgprot_writecombine" [drivers/gpu/drm/i915/i915.ko] undefined!
ERROR: "is_io_mapping_possible" [drivers/gpu/drm/i915/i915.ko] undefined!

Reported-by: Theodore Ts'o <tytso@mit.edu> wrote:
Signed-off-by: Ingo Molnar <mingo@elte.hu>

gpu/drm, x86, PAT: PAT support for io_mapping_*, export symbols for modules

Impact: build fix

ERROR: "reserve_io_memtype_wc" [drivers/gpu/drm/i915/i915.ko] undefined!
ERROR: "free_io_memtype" [drivers/gpu/drm/i915/i915.ko] undefined!

Signed-off-by: Ingo Molnar <mingo@elte.hu>

gpu/drm, x86, PAT: PAT support for io_mapping_*

Make io_mapping_create_wc and io_mapping_free go through PAT to make sure
that there are no memory type aliases.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

gpu/drm, x86, PAT: io_mapping_create_wc and resource_size_t

io_mapping_create_wc should take a resource_size_t parameter in place of
unsigned long. With unsigned long, there will be no way to map greater than 4GB
address in i386/32 bit.

On x86, greater than 4GB addresses cannot be mapped on i386 without PAE. Return
error for such a case.

Patch also adds a structure for io_mapping, that saves the base, size and
type on HAVE_ATOMIC_IOMAP archs, that can be used to verify the offset on
io_mapping_map calls.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: work around PAGE_KERNEL_WC not getting WC in iomap_atomic_prot_pfn.

In the absence of PAT, PAGE_KERNEL_WC ends up mapping to a memory type that
gets UC behavior even in the presence of a WC MTRR covering the area in
question. By swapping to PAGE_KERNEL_UC_MINUS, we can get the actual
behavior the caller wanted (WC if you can manage it, UC otherwise).

This recovers the 40% performance improvement of using WC in the DRM
to upload vertex data.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86: add iomap_atomic*()/iounmap_atomic() on 32-bit using fixmaps

Impact: introduce new APIs, separate kmap code from CONFIG_HIGHMEM

This takes the code used for CONFIG_HIGHMEM memory mappings except that
it's designed for dynamic IO resource mapping.

These fixmaps are available even with CONFIG_HIGHMEM turned off.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>