598841ca ([S390] use gmap address
spaces for kvm guest images) changed kvm to use a separate address
space for kvm guests. This address space was switched in __vcpu_run
In some cases (preemption, page fault) there is the possibility that
this address space switch is lost.
The typical symptom was a huge amount of validity intercepts or
random guest addressing exceptions.
Fix this by doing the switch in sie_loop and sie_exit and saving the
address space in the gmap structure itself. Also use the preempt
notifier.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

Add code that allows KVM to control the virtual memory layout that
is seen by a guest. The guest address space uses a second page table
that shares the last level pte-tables with the process page table.
If a page is unmapped from the process page table it is automatically
unmapped from the guest page table as well.

The guest address space mapping starts out empty, KVM can map any
individual 1MB segments from the process virtual memory to any 1MB
aligned location in the guest virtual memory. If a target segment in
the process virtual memory does not exist or is unmapped while a
guest mapping exists the desired target address is stored as an
invalid segment table entry in the guest page table.
The population of the guest page table is fault driven.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

KVM is not available for 31 bit but the KVM defines cause warnings:

arch/s390/include/asm/pgtable.h: In function 'ptep_test_and_clear_user_dirty':
arch/s390/include/asm/pgtable.h:817: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h:818: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h: In function 'ptep_test_and_clear_user_young':
arch/s390/include/asm/pgtable.h:837: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h:838: warning: integer constant is too large for 'unsigned long' type

Add 31 bit versions of the KVM defines to remove the warnings.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

page_get_storage_key() and page_set_storage_key() expect a page address
and not its page frame number. This got inconsistent with 2d42552d
"[S390] merge page_test_dirty and page_clear_dirty".

Result is that we read/write storage keys from random pages and do not
have a working dirty bit tracking at all.
E.g. SetPageUpdate() doesn't clear the dirty bit of requested pages, which
for example ext4 doesn't like very much and panics after a while.

Unable to handle kernel paging request at virtual user address (null)
Oops: 0004 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 1 Not tainted 2.6.39-07551-g139f37f5-dirty #152
Process flush-94:0 (pid: 1576, task: 000000003eb34538, ksp: 000000003c287b70)
Krnl PSW : 0704c00180000000 0000000000316b12 (jbd2_journal_file_inode+0x10e/0x138)
           R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0700000000000000
           0000000000316a62 000000003eb34cd0 0000000000000025 000000003c287b88
           0000000000000001 000000003c287a70 000000003f1ec678 000000003f1ec000
           0000000000000000 000000003e66ec00 0000000000316a62 000000003c287988
Krnl Code: 0000000000316b04: f0a0000407f4       srp     4(11,%r0),2036,0
           0000000000316b0a: b9020022           ltgr    %r2,%r2
           0000000000316b0e: a7740015           brc     7,316b38
          >0000000000316b12: e3d0c0000024       stg     %r13,0(%r12)
           0000000000316b18: 4120c010           la      %r2,16(%r12)
           0000000000316b1c: 4130d060           la      %r3,96(%r13)
           0000000000316b20: e340d0600004       lg      %r4,96(%r13)
           0000000000316b26: c0e50002b567       brasl   %r14,36d5f4
Call Trace:
([<0000000000316a62>] jbd2_journal_file_inode+0x5e/0x138)
 [<00000000002da13c>] mpage_da_map_and_submit+0x2e8/0x42c
 [<00000000002daac2>] ext4_da_writepages+0x2da/0x504
 [<00000000002597e8>] writeback_single_inode+0xf8/0x268
 [<0000000000259f06>] writeback_sb_inodes+0xd2/0x18c
 [<000000000025a700>] writeback_inodes_wb+0x80/0x168
 [<000000000025aa92>] wb_writeback+0x2aa/0x324
 [<000000000025abde>] wb_do_writeback+0xd2/0x274
 [<000000000025ae3a>] bdi_writeback_thread+0xba/0x1c4
 [<00000000001737be>] kthread+0xa6/0xb0
 [<000000000056c1da>] kernel_thread_starter+0x6/0xc
 [<000000000056c1d4>] kernel_thread_starter+0x0/0xc
INFO: lockdep is turned off.
Last Breaking-Event-Address:
 [<0000000000316a8a>] jbd2_journal_file_inode+0x86/0x138
Reported-by: NSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

Rework the architecture page table functions to access the bits in the
page table extension array (pgste). There are a number of changes:
1) Fix missing pgste update if the attach_count for the mm is <= 1.
2) For every operation that affects the invalid bit in the pte or the
   rcp byte in the pgste the pcl lock needs to be acquired. The function
   pgste_get_lock gets the pcl lock and returns the current pgste value
   for a pte pointer. The function pgste_set_unlock stores the pgste
   and releases the lock. Between these two calls the bits in the pgste
   can be shuffled.
3) Define two software bits in the pte _PAGE_SWR and _PAGE_SWC to avoid
   calling SetPageDirty and SetPageReferenced from pgtable.h. If the
   host reference backup bit or the host change backup bit has been
   set the dirty/referenced state is transfered to the pte. The common
   code will pick up the state from the pte.
4) Add ptep_modify_prot_start and ptep_modify_prot_commit for mprotect.
5) Remove pgd_populate_kernel, pud_populate_kernel, pmd_populate_kernel
   pgd_clear_kernel, pud_clear_kernel, pmd_clear_kernel and ptep_invalidate.
6) Rename kvm_s390_test_and_clear_page_dirty to
   ptep_test_and_clear_user_dirty and add ptep_test_and_clear_user_young.
7) Define mm_exclusive() and mm_has_pgste() helper to improve readability.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The page_clear_dirty primitive always sets the default storage key
which resets the access control bits and the fetch protection bit.
That will surprise a KVM guest that sets non-zero access control
bits or the fetch protection bit. Merge page_test_dirty and
page_clear_dirty back to a single function and only clear the
dirty bit from the storage key.

In addition move the function page_test_and_clear_dirty and
page_test_and_clear_young to page.h where they belong. This
requires to change the parameter from a struct page * to a page
frame number.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The noexec support on s390 does not rely on a bit in the page table
entry but utilizes the secondary space mode to distinguish between
memory accesses for instructions vs. data. The noexec code relies
on the assumption that the cpu will always use the secondary space
page table for data accesses while it is running in the secondary
space mode. Up to the z9-109 class machines this has been the case.
Unfortunately this is not true anymore with z10 and later machines.
The load-relative-long instructions lrl, lgrl and lgfrl access the
memory operand using the same addressing-space mode that has been
used to fetch the instruction.
This breaks the noexec mode for all user space binaries compiled
with march=z10 or later. The only option is to remove the current
noexec support.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Since we no longer need to provide KM_type, the whole pte_*map_nested()
API is now redundant, remove it.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NChris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.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>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All architectures besides s390 have pte_mkhuge() defined in pgtable.h.
So move the function to pgtable.h on s390 as well.
Fixes a compile error introduced with "hugetlb: hugepage migration core"
in linux-next which only happens on s390.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Improve performance of the sske operation by using the nonquiescing
variant if the affected page has no mappings established. On machines
with no support for the new sske variant the mask bit will be ignored.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Use the store indication bit in the translation exception code on
page faults to avoid the protection faults that immediatly follow
the page fault if the access has been a write.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Implement get_user_pages_fast without locking in the fastpath on s390.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

If the zero page is mapped to virtual user space addresses that differ
only in bit 2^12 or 2^13 we get L1 cache synonyms which can affect
performance. Follow the mips model and use multiple zero pages to avoid
the synonyms.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The tlb flushing code uses the mm_users field of the mm_struct to
decide if each page table entry needs to be flushed individually with
IPTE or if a global flush for the mm_struct is sufficient after all page
table updates have been done. The comment for mm_users says "How many
users with user space?" but the /proc code increases mm_users after it
found the process structure by pid without creating a new user process.
Which makes mm_users useless for the decision between the two tlb
flusing methods. The current code can be confused to not flush tlb
entries by a concurrent access to /proc files if e.g. a fork is in
progres. The solution for this problem is to make the tlb flushing
logic independent from the mm_users field.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The default size of the vmalloc area is currently 1 GB. The memory resource
controller uses about 10 MB of vmalloc space per gigabyte of memory. That
turns a system with more than ~100 GB memory unbootable with the default
vmalloc size. It costs us nothing to increase the default size to some
more adequate value, e.g. 128 GB.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

On VIVT ARM, when we have multiple shared mappings of the same file
in the same MM, we need to ensure that we have coherency across all
copies.  We do this via make_coherent() by making the pages
uncacheable.

This used to work fine, until we allowed highmem with highpte - we
now have a page table which is mapped as required, and is not available
for modification via update_mmu_cache().

Ralf Beache suggested getting rid of the PTE value passed to
update_mmu_cache():

  On MIPS update_mmu_cache() calls __update_tlb() which walks pagetables
  to construct a pointer to the pte again.  Passing a pte_t * is much
  more elegant.  Maybe we might even replace the pte argument with the
  pte_t?

Ben Herrenschmidt would also like the pte pointer for PowerPC:

  Passing the ptep in there is exactly what I want.  I want that
  -instead- of the PTE value, because I have issue on some ppc cases,
  for I$/D$ coherency, where set_pte_at() may decide to mask out the
  _PAGE_EXEC.

So, pass in the mapped page table pointer into update_mmu_cache(), and
remove the PTE value, updating all implementations and call sites to
suit.

Includes a fix from Stephen Rothwell:

  sparc: fix fallout from update_mmu_cache API change
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We dont need the dirty bit if a write access is done via the kernel
mapping. In that case SetPageDirty and friends are used anyway, no
need to do that a second time. We can use the change-recording
overide function for the kernel mapping, if available.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

With the kernel parameter 'vmalloc=<size>' the size of the vmalloc area
can be specified. This can be used to increase or decrease the size of
the area. Works in the same way as on some other architectures.
This can be useful for features which make excessive use of vmalloc and
wouldn't work otherwise.
The default sizes remain unchanged: 96MB for 31 bit kernels and 1GB for
64 bit kernels.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

When running several kvm processes with lots of memory overcommitment,
we have seen an oops during process shutdown:
------------[ cut here ]------------
Kernel BUG at 0000000000193434 [verbose debug info unavailable]
addressing exception: 0005 [#1] PREEMPT SMP
Modules linked in: kvm sunrpc qeth_l2 dm_mod qeth ccwgroup
CPU: 10 Not tainted 2.6.28-rc4-kvm-bigiron-00521-g0ccca08-dirty #8
Process kuli (pid: 14460, task: 0000000149822338, ksp: 0000000024f57650)
Krnl PSW : 0704e00180000000 0000000000193434 (unmap_vmas+0x884/0xf10)
R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 EA:3
Krnl GPRS: 0000000000000002 0000000000000000 000000051008d000 000003e05e6034e0
           00000000001933f6 00000000000001e9 0000000407259e0a 00000002be88c400
           00000200001c1000 0000000407259608 0000000407259e08 0000000024f577f0
           0000000407259e09 0000000000445fa8 00000000001933f6 0000000024f577f0
Krnl Code: 0000000000193426: eb22000c000d sllg %r2,%r2,12
           000000000019342c: a7180000 lhi %r1,0
           0000000000193430: b2290012 iske %r1,%r2
          >0000000000193434: a7110002 tmll %r1,2
           0000000000193438: a7840006 brc 8,193444
           000000000019343c: 9602c000 oi 0(%r12),2
           0000000000193440: 96806000 oi 0(%r6),128
           0000000000193444: a7110004 tmll %r1,4
Call Trace:
([<00000000001933f6>] unmap_vmas+0x846/0xf10)
[<0000000000199680>] exit_mmap+0x210/0x458
[<000000000012a8f8>] mmput+0x54/0xfc
[<000000000012f714>] exit_mm+0x134/0x144
[<000000000013120c>] do_exit+0x240/0x878
[<00000000001318dc>] do_group_exit+0x98/0xc8
[<000000000013e6b0>] get_signal_to_deliver+0x30c/0x358
[<000000000010bee0>] do_signal+0xec/0x860
[<0000000000112e30>] sysc_sigpending+0xe/0x22
[<000002000013198a>] 0x2000013198a
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<00000000001a68d0>] free_swap_and_cache+0x1a0/0x1a4
<4>---[ end trace bc19f1d51ac9db7c ]---

The faulting instruction is the storage key operation (iske) in
ptep_rcp_copy (called by pte_clear, called by unmap_vmas). iske
reads dirty and reference bit information for a physical page and
requires a valid physical address. Since we are in pte_clear, we
cannot rely on the pte containing a valid address. Fortunately we
dont need these information in pte_clear - after all there is no
mapping. The best fix is to remove the needless call to ptep_rcp_copy
that contains the iske.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The current enable_sie code sets the mm->context.pgstes bit to tell
dup_mm that the new mm should have extended page tables. This bit is also
used by the s390 specific page table primitives to decide about the page
table layout - which means context.pgstes has two meanings. This can cause
any kind of bugs. For example  - e.g. shrink_zone can call
ptep_clear_flush_young while enable_sie is running. ptep_clear_flush_young
will test for context.pgstes. Since enable_sie changed that value of the old
struct mm without changing the page table layout ptep_clear_flush_young will
do the wrong thing.
The solution is to split pgstes into two bits
- one for the allocation
- one for the current state
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This patch defines a dirty bit in the PGSTE that can be used to implement
dirty pages logging for KVM's live migration. The bit is set in the
ptep_rcp_copy function, which is called to save dirty and referenced information
from the storage key in the PGSTE. The bit can be tested and reset by KVM using
the kvm_s390_test_and_clear_page_dirty function that is introduced by this patch.
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NFlorian Funke <ffunke@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Some macros in pgtable.h access members from struct task_struct.
Currently always works since sched.h seems always to be included
before asm/pgtable.h. Unfortunately that is not anymore true with
Jeremy Fitzhardinge's ptep_modify_prot transaction abstraction patch.
So fix this.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Stop mprotect's pte_modify from wiping out the s390 pte_special bit, which
caused oops thereafter when vm_normal_page thought X's abnormal was normal.
Debugged-by: NRyan Hope <rmh3093@gmail.com>
Debugged-by: NZan Lynx <zlynx@acm.org>
Acked-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Convert s390 to SPARSEMEM and SPARSEMEM_VMEMMAP. We do a select
of SPARSEMEM_VMEMMAP since it is configurable. This is because
SPARSEMEM without SPARSEMEM_VMEMMAP gives us a hell of broken
include dependencies that I don't want to fix.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This adds hugetlbfs support on System z, using both hardware large page
support if available and software large page emulation on older hardware.
Shared (large) page tables are implemented in software emulation mode,
by using page->index of the first tail page from a compound large page
to store page table information.
Signed-off-by: NGerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Convert XIP to support non-struct page backed memory, using VM_MIXEDMAP for
the user mappings.

This requires the get_xip_page API to be changed to an address based one.
Improve the API layering a little bit too, while we're here.

This is required in order to support XIP filesystems on memory that isn't
backed with struct page (but memory with struct page is still supported too).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory
model (which is more dynamic than most).  Instead, they had proposed to
implement it with an additional path through vm_normal_page(), using a bit in
the pte to determine whether or not the page should be refcounted:

vm_normal_page()
{
	...
        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
                if (vma->vm_flags & VM_MIXEDMAP) {
#ifdef s390
			if (!mixedmap_refcount_pte(pte))
				return NULL;
#else
                        if (!pfn_valid(pfn))
                                return NULL;
#endif
                        goto out;
                }
	...
}

This is fine, however if we are allowed to use a bit in the pte to determine
refcountedness, we can use that to _completely_ replace all the vma based
schemes.  So instead of adding more cases to the already complex vma-based
scheme, we can have a clearly seperate and simple pte-based scheme (and get
slightly better code generation in the process):

vm_normal_page()
{
#ifdef s390
	if (!mixedmap_refcount_pte(pte))
		return NULL;
	return pte_page(pte);
#else
	...
#endif
}

And finally, we may rather make this concept usable by any architecture rather
than making it s390 only, so implement a new type of pte state for this.
Unfortunately the old vma based code must stay, because some architectures may
not be able to spare pte bits.  This makes vm_normal_page a little bit more
ugly than we would like, but the 2 cases are clearly seperate.

So introduce a pte_special pte state, and use it in mm/memory.c.  It is
currently a noop for all architectures, so this doesn't actually result in any
compiled code changes to mm/memory.o.

BTW:
I haven't put vm_normal_page() into arch code as-per an earlier suggestion.
The reason is that, regardless of where vm_normal_page is actually
implemented, the *abstraction* is still exactly the same. Also, while it
depends on whether the architecture has pte_special or not, that is the
only two possible cases, and it really isn't an arch specific function --
the role of the arch code should be to provide primitive functions and
accessors with which to build the core code; pte_special does that. We do
not want architectures to know or care about vm_normal_page itself, and
we definitely don't want them being able to invent something new there
out of sight of mm/ code. If we made vm_normal_page an arch function, then
we have to make vm_insert_mixed (next patch) an arch function too. So I
don't think moving it to arch code fundamentally improves any abstractions,
while it does practically make the code more difficult to follow, for both
mm and arch developers, and easier to misuse.

[akpm@linux-foundation.org: build fix]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no need to use interlocked updates when the rcp
lock is held. Therefore the simple bitops variants can be
used. This should improve performance.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

This patch changes the s390 memory management defintions to use the pgste field
for dirty and reference bit tracking of host and guest code. Usually on s390,
dirty and referenced are tracked in storage keys, which belong to the physical
page. This changes with virtualization: The guest and host dirty/reference bits
are defined to be the logical OR of the values for the mapping and the physical
page. This patch implements the necessary changes in pgtable.h for s390.

There is a common code change in mm/rmap.c, the call to
page_test_and_clear_young must be moved. This is a no-op for all
architecture but s390. page_referenced checks the referenced bits for
the physiscal page and for all mappings:
o The physical page is checked with page_test_and_clear_young.
o The mappings are checked with ptep_test_and_clear_young and friends.

Without pgstes (the current implementation on Linux s390) the physical page
check is implemented but the mapping callbacks are no-ops because dirty
and referenced are not tracked in the s390 page tables. The pgstes introduces
guest and host dirty and reference bits for s390 in the host mapping. These
mapping must be checked before page_test_and_clear_young resets the reference
bit.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

The SIE instruction on s390 uses the 2nd half of the page table page to
virtualize the storage keys of a guest. This patch offers the s390_enable_sie
function, which reorganizes the page tables of a single-threaded process to
reserve space in the page table:
s390_enable_sie makes sure that the process is single threaded and then uses
dup_mm to create a new mm with reorganized page tables. The old mm is freed
and the process has now a page status extended field after every page table.

Code that wants to exploit pgstes should SELECT CONFIG_PGSTE.

This patch has a small common code hit, namely making dup_mm non-static.

Edit (Carsten): I've modified Martin's patch, following Jeremy Fitzhardinge's
review feedback. Now we do have the prototype for dup_mm in
include/linux/sched.h. Following Martin's suggestion, s390_enable_sie() does now
call task_lock() to prevent race against ptrace modification of mm_users.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAvi Kivity <avi@qumranet.com>

Add support for different number of page table levels dependent
on the highest address used for a process. This will cause a 31 bit
process to use a two level page table instead of the four level page
table that is the default after the pud has been introduced. Likewise
a normal 64 bit process will use three levels instead of four. Only
if a process runs out of the 4 tera bytes which can be addressed with
a three level page table the fourth level is dynamically added. Then
the process can use up to 8 peta byte.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This patch implements 1K/2K page table pages for s390.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

With the new space saving spinlock_t and a non-debug configuration
the struct page only has 32 bytes for 31 bit s390. The causes an
overflow in the calculation of VMEM_MAX_PHYS which renders the
kernel unbootable.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Remove BUILD_BUG_ON() in vmem code since it causes build failures if
the size of struct page increases. Instead calculate at compile time
the address of the highest physical address that can be added to the
1:1 mapping.
This supposed to fix a build failure with the page owner tracking leak
detector patches as reported by akpm.

page-owner-tracking-leak-detector-broken-on-s390.patch can be removed
from -mm again when this is merged.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Currently the vmalloc area starts at a dynamic address depending on
the memory size. There was also an 8MB security hole after the
physical memory to catch out-of-bounds accesses.
We can simplify the code by putting the vmalloc area explicitely at
the top of the kernel mapping and setting the vmalloc size to a fixed
value of 128MB/128GB for 31bit/64bit systems. Part of the vmalloc
area will be used for the vmem_map. This leaves an area of 96MB/1GB
for normal vmalloc allocations.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Git commit 3610cce8 (yeah my own :-/)
introduced a bug in regard to pud/pmd table entries.
If the address of the page table refered to by a pud/pmd value happens
to have zeroes in the lower 32 bits, pud_present and pmd_present return
false. The obvious effect is that this triggers the BUG_ON in exit_mmap
because some ptes will not get released on process end.  Worse is that
the next fault for memory covered by that pud/pmd will allocate another
pmd/pte table and populate the pud/pmd entry. The old page table
entries hanging below this entry are lost!

The fix is simple, properly check against 0. The check is added for
pud_none/pmd_none as well even if these two functions work because
the invalid bit is in the lower 32 bits.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Get independent from asm-generic/4level-fixup.h
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

- De-confuse the defines for the address-space-control-elements
  and the segment/region table entries.
- Create out of line functions for page table allocation / freeing.
- Simplify get_shadow_xxx functions.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>