We walk over the whole P2M tree and construct a simplified view of
which PFN regions belong to what level and what type they are.

Only enabled if CONFIG_XEN_DEBUG_FS is set.

[v2: UNKN->UNKNOWN, use uninitialized_var]
[v3: Rebased on top of mmu->p2m code split]
[v4: Fixed the else if]
Reviewed-by: NIan Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We walk the E820 region and start at 0 (for PV guests we start
at ISA_END_ADDRESS) and skip any E820 RAM regions. For all other
regions and as well the gaps we set them to be identity mappings.

The reasons we do not want to set the identity mapping from 0->
ISA_END_ADDRESS when running as PV is b/c that the kernel would
try to read DMI information and fail (no permissions to read that).
There is a lot of gnarly code to deal with that weird region so
we won't try to do a cleanup in this patch.

This code ends up calling 'set_phys_to_identity' with the start
and end PFN of the the E820 that are non-RAM or have gaps.
On 99% of machines that means one big region right underneath the
4GB mark. Usually starts at 0xc0000 (or 0x80000) and goes to
0x100000.

[v2: Fix for E820 crossing 1MB region and clamp the start]
[v3: Squshed in code that does this over ranges]
[v4: Moved the comment to the correct spot]
[v5: Use the "raw" E820 from the hypervisor]
[v6: Added Review-by tag]
Reviewed-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The initial bootup code uses set_phys_to_machine quite a lot, and after
bootup it would be used by the balloon driver. The balloon driver does have
mutex lock so this should not be necessary - but just in case, add
a WARN_ON if we do hit this scenario. If we do fail this, it is OK
to continue as there is a backup mechanism (VM_IO) that can bypass
the P2M and still set the _PAGE_IOMAP flags.

[v2: Change from WARN to BUG_ON]
[v3: Rebased on top of xen->p2m code split]
[v4: Change from BUG_ON to WARN]
Reviewed-by: NIan Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

If we find that the PFN is within the P2M as an identity
PFN make sure to tack on the _PAGE_IOMAP flag.
Reviewed-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:

 idx: 0,  1,       2
 [0x290F, 0x290E, 0x290D, ..]

so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.

We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
 pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.

We add the possibility of setting 1-1 mappings on certain regions, so
that:
 pfn_to_mfn(0xc0000)=0xc0000

The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.

For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).

On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).

The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.

This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:

                   1GB                                           2GB
/-------------------+---------\/----\         /----------\    /---+-----\
| System RAM        | Sys RAM ||ACPI|         | reserved |    | Sys RAM |
\-------------------+---------/\----/         \----------/    \---+-----/
                              ^- 1029MB                       ^- 2001MB

[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]

And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).

When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn.  We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).

With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).

Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.

At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").

The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space.  At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier.  If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.

All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."

This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:

   p2m         /--------------\
 /-----\       | &mfn_list[0],|                           /-----------------\
 |  0  |------>| &mfn_list[1],|    /---------------\      | ~0, ~0, ..      |
 |-----|       |  ..., ~0, ~0 |    | ~0, ~0, [x]---+----->| IDENTITY [@256] |
 |  1  |---\   \--------------/    | [p2m_identity]+\     | IDENTITY [@257] |
 |-----|    \                      | [p2m_identity]+\\    | ....            |
 |  2  |--\  \-------------------->|  ...          | \\   \----------------/
 |-----|   \                       \---------------/  \\
 |  3  |\   \                                          \\  p2m_identity
 |-----| \   \-------------------->/---------------\   /-----------------\
 | ..  +->+                        | [p2m_identity]+-->| ~0, ~0, ~0, ... |
 \-----/ /                         | [p2m_identity]+-->| ..., ~0         |
        / /---------------\        | ....          |   \-----------------/
       /  | IDENTITY[@0]  |      /-+-[x], ~0, ~0.. |
      /   | IDENTITY[@256]|<----/  \---------------/
     /    | ~0, ~0, ....  |
    |     \---------------/
    |
    p2m_missing             p2m_missing
/------------------\     /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0    |
\------------------/     \------------/

where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: NIan Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

With this patch, we diligently set regions that will be used by the
balloon driver to be INVALID_P2M_ENTRY and under the ownership
of the balloon driver. We are OK using the __set_phys_to_machine
as we do not expect to be allocating any P2M middle or entries pages.
The set_phys_to_machine has the side-effect of potentially allocating
new pages and we do not want that at this stage.

We can do this because xen_build_mfn_list_list will have already
allocated all such pages up to xen_max_p2m_pfn.

We also move the check for auto translated physmap down the
stack so it is present in __set_phys_to_machine.

[v2: Rebased with mmu->p2m code split]
Reviewed-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

After changing the p2m mapping to a tree by

  commit 58e05027
    xen: convert p2m to a 3 level tree

and trying to boot a DomU with 615MB of memory, the following crash was
observed in the dump:

kernel direct mapping tables up to 26f00000 @ 1ec4000-1fff000
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c0107397>] xen_set_pte+0x27/0x60
*pdpt = 0000000000000000 *pde = 0000000000000000

Adding further debug statements showed that when trying to set up
pfn=0x26700 the returned mapping was invalid.

pfn=0x266ff calling set_pte(0xc1fe77f8, 0x6b3003)
pfn=0x26700 calling set_pte(0xc1fe7800, 0x3)

Although the last_pfn obtained from the startup info is 0x26700, which
should in turn not be hit, the additional 8MB which are added as extra
memory normally seem to be ok. This lead to looking into the initial
p2m tree construction, which uses the smaller value and assuming that
there is other code handling the extra memory.

When the p2m tree is set up, the leaves are directly pointed to the
array which the domain builder set up. But if the mapping is not on a
boundary that fits into one p2m page, this will result in the last leaf
being only partially valid. And as the invalid entries are not
initialized in that case, things go badly wrong.

I am trying to fix that by checking whether the current leaf is a
complete map and if not, allocate a completely new page and copy only
the valid pointers there. This may not be the most efficient or elegant
solution, but at least it seems to allow me booting DomUs with memory
assignments all over the range.

BugLink: http://bugs.launchpad.net/bugs/686692
[v2: Redid a bit of commit wording and fixed a compile warning]
Signed-off-by: NStefan Bader <stefan.bader@canonical.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option
is used to configure any non-standard kernel with a much larger scope than
only small devices.

This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes
references to the option throughout the kernel.  A new CONFIG_EMBEDDED
option is added that automatically selects CONFIG_EXPERT when enabled and
can be used in the future to isolate options that should only be
considered for embedded systems (RISC architectures, SLOB, etc).

Calling the option "EXPERT" more accurately represents its intention: only
expert users who understand the impact of the configuration changes they
are making should enable it.
Reviewed-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NDavid Woodhouse <david.woodhouse@intel.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Greg KH <gregkh@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix sparse warning for non-ANSI function declaration:

arch/x86/xen/irq.c:129:30: warning: non-ANSI function declaration of function 'xen_init_irq_ops'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc:	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized.  During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.

lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available.  While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Honor the kconfig menu hierarchy to remove kconfig dependency warnings:
VIRTIO and VIRTIO_RING are subordinate to VIRTUALIZATION.

warning: (LGUEST_GUEST) selects VIRTIO which has unmet direct dependencies (VIRTUALIZATION)
warning: (LGUEST_GUEST && VIRTIO_PCI && VIRTIO_BALLOON) selects VIRTIO_RING which has unmet direct dependencies (VIRTUALIZATION && VIRTIO)
Reported-by: NToralf F_rster <toralf.foerster@gmx.de>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

arch/x86/lguest/boot.c: In function ‘lguest_init_IRQ’:
arch/x86/lguest/boot.c:824: error: macro "__this_cpu_write" requires 2 arguments, but only 1 given
arch/x86/lguest/boot.c:824: error: ‘__this_cpu_write’ undeclared (first use in this function)
arch/x86/lguest/boot.c:824: error: (Each undeclared identifier is reported only once
arch/x86/lguest/boot.c:824: error: for each function it appears in.)

drivers/lguest/x86/core.c: In function ‘copy_in_guest_info’:
drivers/lguest/x86/core.c:94: error: lvalue required as left operand of assignment
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Use this_cpu_ops in a couple of places in lguest.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

In order to be able to suppress the use of SRAT tables that
32-bit Linux can't deal with (in one case known to lead to a
non-bootable system, unless disabling ACPI altogether), move the
"numa=" option handling to common code.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Reviewed-by: NThomas Renninger <trenn@suse.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Renninger <trenn@suse.de>
LKML-Reference: <4D36B581020000780002D0FF@vpn.id2.novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit 86b1e8dd ("x86: Make relocatable kernel work with
new binutils").

Markus Trippelsdorf reported a boot failure caused by this patch.

The real solution to the original patch will likely involve an
arch-generic solution to define an overlaid jiffies_64 and jiffies
variables.

Until that's done and tested on all architectures revert this commit to
solve the regression.
Reported-and-bisected-by: NMarkus Trippelsdorf <markus@trippelsdorf.de>
Acked-by: N"H. Peter Anvin" <hpa@zytor.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: "Lu, Hongjiu" <hongjiu.lu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <4D36A759.60704@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Mathias Merz reported that v2.6.37 failed to boot on his
system.

Make sure that the thread_info part of the irqstack is
initialized to zeroes.
Reported-and-Tested-by: NMatthias Merz <linux@merz-ka.de>
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Acked-by: NPekka Enberg <penberg@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <AANLkTimyKXfJ1x8tgwrr1hYnNLrPfgE1NTe4z7L6tUDm@mail.gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The CONFIG_RELOCATABLE=y option is broken with new binutils, which will make
boot panic.

According to Lu Hongjiu, the affected binutils are from 2.20.51.0.12 to
2.21.51.0.3, which are release since Oct 22 this year. At least ubuntu 10.10 is
using such binutils. See:

    http://sourceware.org/bugzilla/show_bug.cgi?id=12327

The reason of the boot panic is that we have 'jiffies = jiffies_64;' in
vmlinux.lds.S. The jiffies isn't in any section. In kernel build, there is
warning saying jiffies is an absolute address and can't be relocatable. At
runtime, jiffies will have virtual address 0.

Signed-off-by: Shaohua Li<shaohua.li@intel.com>
Cc: Lu Hongjiu<hongjiu.lu@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
LKML-Reference: <1295312269.1949.725.camel@sli10-conroe>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fixes this build error:

 ERROR: "arbitrary_virt_to_machine" [drivers/xen/xen-gntdev.ko] undefined!
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

OLPC uses select for OLPC_OPENFIRMWARE, which means OLPC has to
enforce the dependencies for OLPC_OPENFIRMWARE.  Make sure it does so.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: Daniel Drake <dsd@laptop.org>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
LKML-Reference: <20100923162846.D8D409D401B@zog.reactivated.net>
Cc: <stable@kernel.org> 2.6.37

Offlining the secondary CPU causes the timer irq affinity to be set to
CPU 0. When the secondary CPU is back online again, the wrong irq
affinity will be used.

This patch ensures secondary per CPU timer always has the correct
IRQ affinity when enabled.
Signed-off-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
LKML-Reference: <1294963604-18111-1-git-send-email-jacob.jun.pan@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org> 2.6.37

Konrad Wilk reported that the new delayed calibration crashes with a
divide by zero on Xen. The reason is that Xen sets the pmtimer
address, but reading from it returns 0xffffff. That results in the
ref_start and ref_stop value being the same, so the delta is zero
which causes the divide by zero later in the calculation.

The conditional (!hpet && !ref_start && !ref_stop) which sanity checks
the calibration reference values doesn't really make sense. If the
refs are null, but hpet is on, we still want to break out.

The div by zero would be possible to trigger by chance if both reads
from the hardware provided the exact same value (due to hardware
wrapping).

So checking if both the ref values are the same should handle if we
don't have hardware (both null) or if they are the same value (either by
invalid hardware, or by chance), avoiding the div by zero issue.

[ tglx: Applied the same fix to native_calibrate_tsc() where this
  	check was copied from ]
Reported-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <1295024788-15619-1-git-send-email-johnstul@us.ibm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This functionality is known to be incomplete, so discourage its use in
general-purpose kernels.

The only reason to use this driver is to support PCI hotplug on CNB20LE-
based machines that don't have ACPI, and there are very few such
systems.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=665109Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The broadcom_bus.c quirk was written (without benefit of documentation)
to support PCI hotplug on an old system that doesn't have ACPI.  As
such, we should only use it when the system doesn't have ACPI.

If the system does have ACPI and we need the host bridge description, we
should get it from the ACPI _CRS method.  On machines older than 2008,
we currently ignore _CRS, but that doesn't mean we should use
broadcom_bus.c.  It means we should either (a) do what we've done in the
past and assume everything in the PCI gap is routed to bus 0 (so hotplug
may not work), or (b) arrange to use _CRS.  This patch does (a).

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=665109Acked-by: NIra W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

This patch enables pci=bfsort by default on future Dell systems.
It reads SMBIOS type 0xB1 vendor specific record and sets pci=bfsort
accordingly.

Offset  Name    Length  Value   Description

04      Flags0  Word    Varies  Bits 9-10
                                - 10:9 = 00  Unknown
                                - 10:9 = 01  Breadth First
                                - 10:9 = 10  Depth First
                                - 10:9 = 11  Reserved

1. Any time pci=bfsort has to be enabled on a system, we need to add the
   model number of the system to the white list. With this patch, that
   is not required.

2. Typically, model number has to be added to the white list when the
   system is under development. With this change, that is not required.
Signed-off-by: NJordan Hargrave <jordan_hargrave@dell.com>
Signed-off-by: NNarendra K <narendra_k@dell.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

The cs5535-mfd driver now takes care of the PCI BAR handling; this
means the olpc-xo1 driver shouldn't be touching the PCI device at all.

This patch uses both cs5535-acpi and cs5535-pms platform devices rather
than a single platform device because the cs5535-mfd driver may be used
by other CS5535 platform-specific drivers; OLPC doesn't get to dictate
that ACPI and PMS will always be used together.
Signed-off-by: NAndres Salomon <dilinger@queued.net>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

For GRU and EPT, we need gup-fast to set referenced bit too (this is why
it's correct to return 0 when shadow_access_mask is zero, it requires
gup-fast to set the referenced bit).  qemu-kvm access already sets the
young bit in the pte if it isn't zero-copy, if it's zero copy or a shadow
paging EPT minor fault we relay on gup-fast to signal the page is in
use...

We also need to check the young bits on the secondary pagetables for NPT
and not nested shadow mmu as the data may never get accessed again by the
primary pte.

Without this closer accuracy, we'd have to remove the heuristic that
avoids collapsing hugepages in hugepage virtual regions that have not even
a single subpage in use.

->test_young is full backwards compatible with GRU and other usages that
don't have young bits in pagetables set by the hardware and that should
nuke the secondary mmu mappings when ->clear_flush_young runs just like
EPT does.

Removing the heuristic that checks the young bit in
khugepaged/collapse_huge_page completely isn't so bad either probably but
I thought it was worth it and this makes it reliable.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Archs implementing Transparent Hugepage Support must implement a function
called has_transparent_hugepage to be sure the virtual or physical CPU
supports Transparent Hugepages.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add pmd_modify() for use with mprotect() on huge pmds.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add support for transparent hugepages to x86 32bit.

Share the same VM_ bitflag for VM_MAPPED_COPY.  mm/nommu.c will never
support transparent hugepages.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Lately I've been working to make KVM use hugepages transparently without
the usual restrictions of hugetlbfs.  Some of the restrictions I'd like to
see removed:

1) hugepages have to be swappable or the guest physical memory remains
   locked in RAM and can't be paged out to swap

2) if a hugepage allocation fails, regular pages should be allocated
   instead and mixed in the same vma without any failure and without
   userland noticing

3) if some task quits and more hugepages become available in the
   buddy, guest physical memory backed by regular pages should be
   relocated on hugepages automatically in regions under
   madvise(MADV_HUGEPAGE) (ideally event driven by waking up the
   kernel deamon if the order=HPAGE_PMD_SHIFT-PAGE_SHIFT list becomes
   not null)

4) avoidance of reservation and maximization of use of hugepages whenever
   possible. Reservation (needed to avoid runtime fatal faliures) may be ok for
   1 machine with 1 database with 1 database cache with 1 database cache size
   known at boot time. It's definitely not feasible with a virtualization
   hypervisor usage like RHEV-H that runs an unknown number of virtual machines
   with an unknown size of each virtual machine with an unknown amount of
   pagecache that could be potentially useful in the host for guest not using
   O_DIRECT (aka cache=off).

hugepages in the virtualization hypervisor (and also in the guest!) are
much more important than in a regular host not using virtualization,
becasue with NPT/EPT they decrease the tlb-miss cacheline accesses from 24
to 19 in case only the hypervisor uses transparent hugepages, and they
decrease the tlb-miss cacheline accesses from 19 to 15 in case both the
linux hypervisor and the linux guest both uses this patch (though the
guest will limit the addition speedup to anonymous regions only for
now...).  Even more important is that the tlb miss handler is much slower
on a NPT/EPT guest than for a regular shadow paging or no-virtualization
scenario.  So maximizing the amount of virtual memory cached by the TLB
pays off significantly more with NPT/EPT than without (even if there would
be no significant speedup in the tlb-miss runtime).

The first (and more tedious) part of this work requires allowing the VM to
handle anonymous hugepages mixed with regular pages transparently on
regular anonymous vmas.  This is what this patch tries to achieve in the
least intrusive possible way.  We want hugepages and hugetlb to be used in
a way so that all applications can benefit without changes (as usual we
leverage the KVM virtualization design: by improving the Linux VM at
large, KVM gets the performance boost too).

The most important design choice is: always fallback to 4k allocation if
the hugepage allocation fails!  This is the _very_ opposite of some large
pagecache patches that failed with -EIO back then if a 64k (or similar)
allocation failed...

Second important decision (to reduce the impact of the feature on the
existing pagetable handling code) is that at any time we can split an
hugepage into 512 regular pages and it has to be done with an operation
that can't fail.  This way the reliability of the swapping isn't decreased
(no need to allocate memory when we are short on memory to swap) and it's
trivial to plug a split_huge_page* one-liner where needed without
polluting the VM.  Over time we can teach mprotect, mremap and friends to
handle pmd_trans_huge natively without calling split_huge_page*.  The fact
it can't fail isn't just for swap: if split_huge_page would return -ENOMEM
(instead of the current void) we'd need to rollback the mprotect from the
middle of it (ideally including undoing the split_vma) which would be a
big change and in the very wrong direction (it'd likely be simpler not to
call split_huge_page at all and to teach mprotect and friends to handle
hugepages instead of rolling them back from the middle).  In short the
very value of split_huge_page is that it can't fail.

The collapsing and madvise(MADV_HUGEPAGE) part will remain separated and
incremental and it'll just be an "harmless" addition later if this initial
part is agreed upon.  It also should be noted that locking-wise replacing
regular pages with hugepages is going to be very easy if compared to what
I'm doing below in split_huge_page, as it will only happen when
page_count(page) matches page_mapcount(page) if we can take the PG_lock
and mmap_sem in write mode.  collapse_huge_page will be a "best effort"
that (unlike split_huge_page) can fail at the minimal sign of trouble and
we can try again later.  collapse_huge_page will be similar to how KSM
works and the madvise(MADV_HUGEPAGE) will work similar to
madvise(MADV_MERGEABLE).

The default I like is that transparent hugepages are used at page fault
time.  This can be changed with
/sys/kernel/mm/transparent_hugepage/enabled.  The control knob can be set
to three values "always", "madvise", "never" which mean respectively that
hugepages are always used, or only inside madvise(MADV_HUGEPAGE) regions,
or never used.  /sys/kernel/mm/transparent_hugepage/defrag instead
controls if the hugepage allocation should defrag memory aggressively
"always", only inside "madvise" regions, or "never".

The pmd_trans_splitting/pmd_trans_huge locking is very solid.  The
put_page (from get_user_page users that can't use mmu notifier like
O_DIRECT) that runs against a __split_huge_page_refcount instead was a
pain to serialize in a way that would result always in a coherent page
count for both tail and head.  I think my locking solution with a
compound_lock taken only after the page_first is valid and is still a
PageHead should be safe but it surely needs review from SMP race point of
view.  In short there is no current existing way to serialize the O_DIRECT
final put_page against split_huge_page_refcount so I had to invent a new
one (O_DIRECT loses knowledge on the mapping status by the time gup_fast
returns so...).  And I didn't want to impact all gup/gup_fast users for
now, maybe if we change the gup interface substantially we can avoid this
locking, I admit I didn't think too much about it because changing the gup
unpinning interface would be invasive.

If we ignored O_DIRECT we could stick to the existing compound refcounting
code, by simply adding a get_user_pages_fast_flags(foll_flags) where KVM
(and any other mmu notifier user) would call it without FOLL_GET (and if
FOLL_GET isn't set we'd just BUG_ON if nobody registered itself in the
current task mmu notifier list yet).  But O_DIRECT is fundamental for
decent performance of virtualized I/O on fast storage so we can't avoid it
to solve the race of put_page against split_huge_page_refcount to achieve
a complete hugepage feature for KVM.

Swap and oom works fine (well just like with regular pages ;).  MMU
notifier is handled transparently too, with the exception of the young bit
on the pmd, that didn't have a range check but I think KVM will be fine
because the whole point of hugepages is that EPT/NPT will also use a huge
pmd when they notice gup returns pages with PageCompound set, so they
won't care of a range and there's just the pmd young bit to check in that
case.

NOTE: in some cases if the L2 cache is small, this may slowdown and waste
memory during COWs because 4M of memory are accessed in a single fault
instead of 8k (the payoff is that after COW the program can run faster).
So we might want to switch the copy_huge_page (and clear_huge_page too) to
not temporal stores.  I also extensively researched ways to avoid this
cache trashing with a full prefault logic that would cow in 8k/16k/32k/64k
up to 1M (I can send those patches that fully implemented prefault) but I
concluded they're not worth it and they add an huge additional complexity
and they remove all tlb benefits until the full hugepage has been faulted
in, to save a little bit of memory and some cache during app startup, but
they still don't improve substantially the cache-trashing during startup
if the prefault happens in >4k chunks.  One reason is that those 4k pte
entries copied are still mapped on a perfectly cache-colored hugepage, so
the trashing is the worst one can generate in those copies (cow of 4k page
copies aren't so well colored so they trashes less, but again this results
in software running faster after the page fault).  Those prefault patches
allowed things like a pte where post-cow pages were local 4k regular anon
pages and the not-yet-cowed pte entries were pointing in the middle of
some hugepage mapped read-only.  If it doesn't payoff substantially with
todays hardware it will payoff even less in the future with larger l2
caches, and the prefault logic would blot the VM a lot.  If one is
emebdded transparent_hugepage can be disabled during boot with sysfs or
with the boot commandline parameter transparent_hugepage=0 (or
transparent_hugepage=2 to restrict hugepages inside madvise regions) that
will ensure not a single hugepage is allocated at boot time.  It is simple
enough to just disable transparent hugepage globally and let transparent
hugepages be allocated selectively by applications in the MADV_HUGEPAGE
region (both at page fault time, and if enabled with the
collapse_huge_page too through the kernel daemon).

This patch supports only hugepages mapped in the pmd, archs that have
smaller hugepages will not fit in this patch alone.  Also some archs like
power have certain tlb limits that prevents mixing different page size in
the same regions so they will not fit in this framework that requires
"graceful fallback" to basic PAGE_SIZE in case of physical memory
fragmentation.  hugetlbfs remains a perfect fit for those because its
software limits happen to match the hardware limits.  hugetlbfs also
remains a perfect fit for hugepage sizes like 1GByte that cannot be hoped
to be found not fragmented after a certain system uptime and that would be
very expensive to defragment with relocation, so requiring reservation.
hugetlbfs is the "reservation way", the point of transparent hugepages is
not to have any reservation at all and maximizing the use of cache and
hugepages at all times automatically.

Some performance result:

vmx andrea # LD_PRELOAD=/usr/lib64/libhugetlbfs.so HUGETLB_MORECORE=yes HUGETLB_PATH=/mnt/huge/ ./largep
ages3
memset page fault 1566023
memset tlb miss 453854
memset second tlb miss 453321
random access tlb miss 41635
random access second tlb miss 41658
vmx andrea # LD_PRELOAD=/usr/lib64/libhugetlbfs.so HUGETLB_MORECORE=yes HUGETLB_PATH=/mnt/huge/ ./largepages3
memset page fault 1566471
memset tlb miss 453375
memset second tlb miss 453320
random access tlb miss 41636
random access second tlb miss 41637
vmx andrea # ./largepages3
memset page fault 1566642
memset tlb miss 453417
memset second tlb miss 453313
random access tlb miss 41630
random access second tlb miss 41647
vmx andrea # ./largepages3
memset page fault 1566872
memset tlb miss 453418
memset second tlb miss 453315
random access tlb miss 41618
random access second tlb miss 41659
vmx andrea # echo 0 > /proc/sys/vm/transparent_hugepage
vmx andrea # ./largepages3
memset page fault 2182476
memset tlb miss 460305
memset second tlb miss 460179
random access tlb miss 44483
random access second tlb miss 44186
vmx andrea # ./largepages3
memset page fault 2182791
memset tlb miss 460742
memset second tlb miss 459962
random access tlb miss 43981
random access second tlb miss 43988

============
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>

#define SIZE (3UL*1024*1024*1024)

int main()
{
	char *p = malloc(SIZE), *p2;
	struct timeval before, after;

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset page fault %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset second tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	for (p2 = p; p2 < p+SIZE; p2 += 4096)
		*p2 = 0;
	gettimeofday(&after, NULL);
	printf("random access tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	for (p2 = p; p2 < p+SIZE; p2 += 4096)
		*p2 = 0;
	gettimeofday(&after, NULL);
	printf("random access second tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	return 0;
}
============
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This should work for both hugetlbfs and transparent hugepages.

[akpm@linux-foundation.org: bring forward PageTransCompound() addition for bisectability]
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

split_huge_page_pmd compat code.  Each one of those would need to be
expanded to hundred of lines of complex code without a fully reliable
split_huge_page_pmd design.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

pte alloc routines must wait for split_huge_page if the pmd is not present
and not null (i.e.  pmd_trans_splitting).  The additional branches are
optimized away at compile time by pmd_trans_splitting if the config option
is off.  However we must pass the vma down in order to know the anon_vma
lock to wait for.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Force gup_fast to take the slow path and block if the pmd is splitting,
not only if it's none.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add needed pmd mangling functions with symmetry with their pte
counterparts.  pmdp_splitting_flush() is the only new addition on the pmd_
methods and it's needed to serialize the VM against split_huge_page.  It
simply atomically sets the splitting bit in a similar way
pmdp_clear_flush_young atomically clears the accessed bit.
pmdp_splitting_flush() also has to flush the tlb to make it effective
against gup_fast, but it wouldn't really require to flush the tlb too.
Just the tlb flush is the simplest operation we can invoke to serialize
pmdp_splitting_flush() against gup_fast.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These returns 0 at compile time when the config option is disabled, to
allow gcc to eliminate the transparent hugepage function calls at compile
time without additional #ifdefs (only the export of those functions have
to be visible to gcc but they won't be required at link time and
huge_memory.o can be not built at all).

_PAGE_BIT_UNUSED1 is never used for pmd, only on pte.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No paravirt version of set_pmd_at/pmd_update/pmd_update_defer.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Paravirt ops pmd_update/pmd_update_defer/pmd_set_at.  Not all might be
necessary (vmware needs pmd_update, Xen needs set_pmd_at, nobody needs
pmd_update_defer), but this is to keep full simmetry with pte paravirt
ops, which looks cleaner and simpler from a common code POV.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Used by paravirt and not paravirt set_pmd_at.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Alter compound get_page/put_page to keep references on subpages too, in
order to allow __split_huge_page_refcount to split an hugepage even while
subpages have been pinned by one of the get_user_pages() variants.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>