The radix tree rework removed all code that uses the gmap_rmap
and gmap_pgtable data structures. Remove these outdated definitions.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Add an addressing limit to the gmap address spaces and only allocate
the page table levels that are needed for the given limit. The limit
is fixed and can not be changed after a gmap has been created.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Store the target address for the gmap segments in a radix tree
instead of using invalid segment table entries. gmap_translate
becomes a simple radix_tree_lookup, gmap_fault is split into the
address translation with gmap_translate and the part that does
the linking of the gmap shadow page table with the process page
table.
A second radix tree is used to keep the pointers to the segment
table entries for segments that are mapped in the guest address
space. On unmap of a segment the pointer is retrieved from the
radix tree and is used to carry out the segment invalidation in
the gmap shadow page table. As the radix tree can only store one
pointer, each host segment may only be mapped to exactly one
guest location.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Make the order of arguments for the gmap calls more consistent,
if the gmap pointer is passed it is always the first argument.
In addition distinguish between guest address and user address
by naming the variables gaddr for a guest address and vmaddr for
a user address.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Revert git commit c3a23b9874c1 ("remove unnecessary parameter from
gmap_do_ipte_notify").
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Revert git commit 1b7fd6952063 ("remove unecessary parameter from
pgste_ipte_notify")
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The large segment table entry format has block of bits for the
ACC/F values for the large page. These bits are valid only if
another bit (AV bit 0x10000) of the segment table entry is set.
The ACC/F bits do not have a meaning if the AV bit is off.
This allows to put the THP splitting bit, the segment young bit
and the new segment dirty bit into the ACC/F bits as long as
the AV bit stays off. The dirty and young information is only
available if the pmd is large.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

For live migration kvm needs to test and clear the dirty bit of guest pages.

That for is ptep_test_and_clear_user_dirty, to be sure we are not racing with
other code, we protect the pte. This needs to be done within
the architecture memory management code.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Switch the user dirty bit detection used for migration from the hardware
provided host change-bit in the pgste to a fault based detection method.
This reduced the dependency of the host from the storage key to a point
where it becomes possible to enable the RCP bypass for KVM guests.

The fault based dirty detection will only indicate changes caused
by accesses via the guest address space. The hardware based method
can detect all changes, even those caused by I/O or accesses via the
kernel page table. The KVM/qemu code needs to take this into account.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Introduce a new function s390_enable_skey(), which enables storage key
handling via setting the use_skey flag in the mmu context.

This function is only useful within the context of kvm.

Note that enabling storage keys will cause a one-time hickup when
walking the page table; however, it saves us special effort for cases
like clear reset while making it possible for us to be architecture
conform.

s390_enable_skey() takes the page table lock to prevent reseting
storage keys triggered from multiple vcpus.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

For lazy storage key handling, we need a mechanism to track if the
process ever issued a storage key operation.

This patch adds the basic infrastructure for making the storage
key handling optional, but still leaves it enabled for now by default.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The zEC12 machines introduced the local-clearing control for the IDTE
and IPTE instruction. If the control is set only the TLB of the local
CPU is cleared of entries, either all entries of a single address space
for IDTE, or the entry for a single page-table entry for IPTE.
Without the local-clearing control the TLB flush is broadcasted to all
CPUs in the configuration, which is expensive.

The reset of the bit mask of the CPUs that need flushing after a
non-local IDTE is tricky. As TLB entries for an address space remain
in the TLB even if the address space is detached a new bit field is
required to keep track of attached CPUs vs. CPUs in the need of a
flush. After a non-local flush with IDTE the bit-field of attached CPUs
is copied to the bit-field of CPUs in need of a flush. The ordering
of operations on cpu_attach_mask, attach_count and mm_cpumask(mm) is
such that an underindication in mm_cpumask(mm) is prevented but an
overindication in mm_cpumask(mm) is possible.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This patch enables Collaborative Memory Management (CMM) for kvm
on s390. CMM allows the guest to inform the host about page usage
(see arch/s390/mm/cmm.c). The host uses this information to avoid
swapping in unused pages in the page fault handler. Further, a CPU
provided list of unused invalid pages is processed to reclaim swap
space of not yet accessed unused pages.

[ Martin Schwidefsky: patch reordering and cleanup ]
Signed-off-by: NKonstantin Weitz <konstantin.weitz@gmail.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Git commit 050eef36 "[S390] fix tlb flushing vs. concurrent
/proc accesses" introduced the attach counter to avoid using the
mm_users value to decide between IPTE for every PTE and lazy TLB
flushing with IDTE. That fixed the problem with mm_users but it
introduced another subtle race, fortunately one that is very hard
to hit.
The background is the requirement of the architecture that a valid
PTE may not be changed while it can be used concurrently by another
cpu. The decision between IPTE and lazy TLB flushing needs to be
done while the PTE is still valid. Now if the virtual cpu is
temporarily stopped after the decision to use lazy TLB flushing but
before the invalid bit of the PTE has been set, another cpu can attach
the mm, find that flush_mm is set, do the IDTE, return to userspace,
and recreate a TLB that uses the PTE in question. When the first,
stopped cpu continues it will change the PTE while it is attached on
another cpu. The first cpu will do another IDTE shortly after the
modification of the PTE which makes the race window quite short.

To fix this race the CPU that wants to attach the address space of a
user space thread needs to wait for the end of the PTE modification.
The number of concurrent TLB flushers for an mm is tracked in the
upper 16 bits of the attach_count and finish_arch_post_lock_switch
is used to wait for the end of the flush operation if required.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

In the case of a fault, we will retry to exit sie64 but with gmap fault
indication for this thread set. This makes it possible to handle async
page faults.

Based on a patch from Martin Schwidefsky.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

For machines without enhanced supression on protection the software
dirty bit code forces the pte dirty bit and clears the page protection
bit in pgste_set_pte. This is done for all pte types, the check for
present ptes is missing. As a result swap ptes and other not-present
ptes can get corrupted.
Add a check for the _PAGE_PRESENT bit to pgste_set_pte before modifying
the pte value.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The last remaining use for the storage key of the s390 architecture
is reference counting. The alternative is to make page table entries
invalid while they are old. On access the fault handler marks the
pte/pmd as young which makes the pte/pmd valid if the access rights
allow read access. The pte/pmd invalidations required for software
managed reference bits cost a bit of performance, on the other hand
the RRBE/RRBM instructions to read and reset the referenced bits are
quite expensive as well.
Reviewed-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

For a single-threaded KVM guest ptep_modify_prot_start will not use
IPTE, the invalid bit will therefore not be set. If DEBUG_VM is set
pgste_set_key called by ptep_modify_prot_commit will complain about
the missing invalid bit. ptep_modify_prot_start should set the
invalid bit in all cases.

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Isolate the logic of IDTE vs. IPTE flushing of ptes in two functions,
ptep_flush_lazy and __tlb_flush_mm_lazy.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

ptep_modify_prot_start uses the pgste_set helper to store the pgste,
while ptep_modify_prot_commit uses its own pointer magic to retrieve
the value again. Add the pgste_get help function to keep things
symmetrical and improve readability.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

On process exit there is no more need for the pgste information.
Skip the expensive storage key operations which should speed up
termination of KVM processes.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Improve the encoding of the different pte types and the naming of the
page, segment table and region table bits. Due to the different pte
encoding the hugetlbfs primitives need to be adapted as well. To improve
compatability with common code make the huge ptes use the encoding of
normal ptes. The conversion between the pte and pmd encoding for a huge
pte is done with set_huge_pte_at and huge_ptep_get.
Overall the code is now easier to understand.
Reviewed-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Improve the code to upgrade the standard 2K page tables to 4K page tables
with PGSTEs to allow the operation to happen when the program is already
multi-threaded.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This will be later used by powerpc THP support.  In powerpc we want to use
pgtable for storing the hash index values.  So instead of adding them to
mm_context list, we would like to store them in the second half of pmd
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reviewed-by: NAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: NDavid Gibson <david@gibson.dropbear.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Getting and Releasing the pgste lock has lock semantics. Make the
code an explicit barrier.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

In modify_prot_start we update the pgste value but never store it back
into the original location. Lets save the calculated result, since
modify_prot_commit will use the value of the pgste.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

When doing the transition invalid->valid in the host page table for
a guest, then the guest view of C/R is in the pgste. After validation
the view is pgste OR real key. We must zero out the real key C/R to
avoid guest over-indication for change (and reference).

Touching the real key is ok also for the host: The change bit is
tracked via write protection and the reference bit is also ok
because set_pte_at was called and  the page will be touched anyway
soon. Furthermore architecture defines reference as "substantially
accurate", over- and underindication are ok.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

pte_present might return true on PAGE_TYPE_NONE, even if
the invalid bit is on. Modify the existing check of the
pgste functions to avoid crashes.

[ Martin Schwidefsky: added ptep_modify_prot_[start|commit] bits ]
Reported-by: NMartin Schwidefky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
CC: stable@vger.kernel.org
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The guest prefix pages must be mapped writeable all the time
while SIE is running, otherwise the guest might see random
behaviour. (pinned at the pte level) Turns out that mlocking is
not enough, the page table entry (not the page) might change or
become r/o. This patch uses the gmap notifiers to kick guest
cpus out of SIE.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

The RCP byte is a part of the PGSTE value, the existing RCP_xxx names
are inaccurate. As the defines describe bits and pieces of the PGSTE,
the names should start with PGSTE_. The KVM_UR_BIT and KVM_UC_BIT are
part of the PGSTE as well, give them better names as well.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

Dont use the same bit as user referenced.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

Dont use the same bit as user referenced.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Add a notifier for kvm to get control before a page table entry is
invalidated. The notifier is only called for ptes of an address space
with pgstes that have been explicitly marked to require notification.
Kvm will use this to get control before prefix pages of virtual CPU
are unmapped.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Commit abf09bed ("s390/mm: implement software dirty bits")
introduced another difference in the pte layout vs.  the pmd layout on
s390, thoroughly breaking the s390 support for hugetlbfs.  This requires
replacing some more pte_xxx functions in mm/hugetlbfs.c with a
huge_pte_xxx version.

This patch introduces those huge_pte_xxx functions and their generic
implementation in asm-generic/hugetlb.h, which will now be included on
all architectures supporting hugetlbfs apart from s390.  This change
will be a no-op for those architectures.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>	[for !s390 parts]
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.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>

Implement gmap_translate() function which translates a guest absolute address
to a user space process address without establishing the guest page table
entries.

This is useful for kvm guest address translations where no memory access
is expected to happen soon (e.g. tprot exception handler).
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Commit b4cbb197 ("vm: add vm_iomap_memory() helper function") added
a helper function wrapper around io_remap_pfn_range(), and every other
architecture defined it in <asm/pgtable.h>.

The s390 choice of <asm/io.h> may make sense, but is not very convenient
for this case, and gratuitous differences like that cause unexpected errors like this:

   mm/memory.c: In function 'vm_iomap_memory':
   mm/memory.c:2439:2: error: implicit declaration of function 'io_remap_pfn_range' [-Werror=implicit-function-declaration]

Glory be the kbuild test robot who noticed this, bisected it, and
reported it to the guilty parties (ie me).

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All architectures need to provide a check_pgt_cache() function. The s390 one
got lost somewhere.
So reintroduce it to prevent future compile errors e.g. if Thomas Gleixner's
idle loop rework patches get merged.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>