We have certain SIE features that we cannot support for now.
Let's add these features, so user space can directly prepare to enable
them, so we don't have to update yet another component.

In addition, add a comment block, telling why it is for now not possible to
forward/enable these features.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Whenever we want to wake up a VCPU (e.g. when injecting an IRQ), we
have to kick it out of vsie, so the request will be handled faster.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily enable ibs for guest 2, so he can use it for guest 3.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily enable cei for guest 2, so he can use it for guest 3.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily enable intervention bypass for guest 2, so it can use it
for guest 3.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily forward guest-storage-limit-suppression if available.

One thing to care about is keeping the prefix properly mapped when
gsls in toggled on/off or the mso changes in between. Therefore we better
remap the prefix on any mso changes just like we already do with the
prefix.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily forward the guest-PER-enhancement facility to guest 2 if
available.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

As we forward the whole SCA provided by guest 2, we can directly forward
SIIF if available.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's provide the 64-bit-SCAO facility to guest 2, so he can set up a SCA
for guest 3 that has a 64 bit address. Please note that we already require
the 64 bit SCAO for our vsie implementation, in order to forward the SCA
directly (by pinning the page).
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

As soon as guest 2 is allowed to use the vector facility (indicated via
STFLE), it can also enable it for guest 3. We have to take care of the
sattellite block that might be used when not relying on lazy vector
copying (not the case for KVM).
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

This patch adds basic support for nested virtualization on s390x, called
VSIE (virtual SIE) and allows it to be used by the guest if the necessary
facilities are supported by the hardware and enabled for the guest.

In order to make this work, we have to shadow the sie control block
provided by guest 2. In order to gain some performance, we have to
reuse the same shadow blocks as good as possible. For now, we allow
as many shadow blocks as we have VCPUs (that way, every VCPU can run the
VSIE concurrently).

We have to watch out for the prefix getting unmapped out of our shadow
gmap and properly get the VCPU out of VSIE in that case, to fault the
prefix pages back in. We use the PROG_REQUEST bit for that purpose.

This patch is based on an initial prototype by Tobias Elpelt.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Acked-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Nested virtualization will have to enable own gmaps. Current code
would enable the wrong gmap whenever scheduled out and back in,
therefore resulting in the wrong gmap being enabled.

This patch reenables the last enabled gmap, therefore avoiding having to
touch vcpu->arch.gmap when enabling a different gmap.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

It will be very helpful to have a mechanism to check without any locks
if a given gmap shadow is still valid and matches the given properties.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

For nested virtualization, we want to know if we are handling a protection
exception, because these can directly be forwarded to the guest without
additional checks.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can easily support real-space designation just like EDAT1 and EDAT2.
So guest2 can provide for guest3 an asce with the real-space control being
set.

We simply have to allocate the biggest page table possible and fake all
levels.

There is no protection to consider. If we exceed guest memory, vsie code
will inject an addressing exception (via program intercept). In the future,
we could limit the fake table level to the gmap page table.

As the top level page table can never go away, such gmap shadows will never
get unshadowed, we'll have to come up with another way to limit the number
of kept gmap shadows.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

If the guest is enabled for EDAT2, we can easily create shadows for
guest2 -> guest3 provided tables that make use of EDAT2.

If guest2 references a 2GB page, this memory looks consecutive for guest2,
but it does not have to be so for us. Therefore we have to create fake
segment and page tables.

This works just like EDAT1 support, so page tables are removed when the
parent table (r3t table entry) is changed.

We don't hve to care about:
- ACCF-Validity Control in RTTE
- Access-Control Bits in RTTE
- Fetch-Protection Bit in RTTE
- Common-Region Bit in RTTE

Just like for EDAT1, all bits might be dropped and there is no guaranteed
that they are active.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

If the guest is enabled for EDAT1, we can easily create shadows for
guest2 -> guest3 provided tables that make use of EDAT1.

If guest2 references a 1MB page, this memory looks consecutive for guest2,
but it might not be so for us. Therefore we have to create fake page tables.

We can easily add that to our existing infrastructure. The invalidation
mechanism will make sure that fake page tables are removed when the parent
table (sgt table entry) is changed.

As EDAT1 also introduced protection on all page table levels, we have to
also shadow these correctly.

We don't have to care about:
- ACCF-Validity Control in STE
- Access-Control Bits in STE
- Fetch-Protection Bit in STE
- Common-Segment Bit in STE

As all bits might be dropped and there is no guaranteed that they are
active ("unpredictable whether the CPU uses these bits", "may be used").
Without using EDAT1 in the shadow ourselfes (STE-format control == 0),
simply shadowing these bits would not be enough. They would be ignored.

Please note that we are using the "fake" flag to make this look consistent
with further changes (EDAT2, real-space designation support) and don't let
the shadow functions handle fc=1 stes.

In the future, with huge pages in the host, gmap_shadow_pgt() could simply
try to map a huge host page if "fake" is set to one and indicate via return
value that no lower fake tables / shadow ptes are required.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

In preparation for EDAT1/EDAT2 support for gmap shadows, we have to store
the requested edat level in the gmap shadow.

The edat level used during shadow translation is a property of the gmap
shadow. Depending on that level, the gmap shadow will look differently for
the same guest tables. We have to store it internally in order to support
it later.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Before any thread is allowed to use a gmap_shadow, it has to be fully
initialized. However, for invalidation to work properly, we have to
register the new gmap_shadow before we protect the parent gmap table.

Because locking is tricky, and we have to avoid duplicate gmaps, let's
introduce an initialized field, that signalizes other threads if that
gmap_shadow can already be used or if they have to retry.

Let's properly return errors using ERR_PTR() instead of simply returning
NULL, so a caller can properly react on the error.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We really want to avoid manually handling protection for nested
virtualization. By shadowing pages with the protection the guest asked us
for, the SIE can handle most protection-related actions for us (e.g.
special handling for MVPG) and we can directly forward protection
exceptions to the guest.

PTEs will now always be shadowed with the correct _PAGE_PROTECT flag.
Unshadowing will take care of any guest changes to the parent PTE and
any host changes to the host PTE. If the host PTE doesn't have the
fitting access rights or is not available, we have to fix it up.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

For a nested KVM guest the outer KVM host needs to create shadow
page tables for the nested guest. This patch adds the basic support
to the guest address space (gmap) code.

For each guest address space the inner KVM host creates, the first
outer KVM host needs to create shadow page tables. The address space
is identified by the ASCE loaded into the control register 1 at the
time the inner SIE instruction for the second nested KVM guest is
executed. The outer KVM host creates the shadow tables starting with
the table identified by the ASCE on a on-demand basis. The outer KVM
host will get repeated faults for all the shadow tables needed to
run the second KVM guest.

While a shadow page table for the second KVM guest is active the access
to the origin region, segment and page tables needs to be restricted
for the first KVM guest. For region and segment and page tables the first
KVM guest may read the memory, but write attempt has to lead to an
unshadow.  This is done using the page invalid and read-only bits in the
page table of the first KVM guest. If the first guest re-accesses one of
the origin pages of a shadow, it gets a fault and the affected parts of
the shadow page table hierarchy needs to be removed again.

PGSTE tables don't have to be shadowed, as all interpretation assist can't
deal with the invalid bits in the shadow pte being set differently than
the original ones provided by the first KVM guest.

Many bug fixes and improvements by David Hildenbrand.
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's use a reference counter mechanism to control the lifetime of
gmap structures. This will be needed for further changes related to
gmap shadows.
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The current gmap pte notifier forces a pte into to a read-write state.
If the pte is invalidated the gmap notifier is called to inform KVM
that the mapping will go away.

Extend this approach to allow read-write, read-only and no-access
as possible target states and call the pte notifier for any change
to the pte.

This mechanism is used to temporarily set specific access rights for
a pte without doing the heavy work of a true mprotect call.
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The gmap notifier list and the gmap list in the mm_struct change rarely.
Use RCU to optimize the reader of these lists.
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Pass an address range to the page table invalidation notifier
for KVM. This allows to notify changes that affect a larger
virtual memory area, e.g. for 1MB pages.
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Without the storage-key facility, SIE won't interpret SSKE, ISKE and
RRBE for us. So let's add proper interception handlers that will be called
if lazy sske cannot be enabled.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's correctly detect that facility.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We already indicate that facility but don't implement it in our pfmf
interception handler. Let's add a new storage key handling function for
conditionally setting the guest storage key.

As we will reuse this function later on, let's directly implement returning
the old key via parameter and indicating if any change happened via rc.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's just split returning the key and reporting errors. This makes calling
code easier and avoids bugs as happened already.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Commit 1e133ab2 ("s390/mm: split arch/s390/mm/pgtable.c") changed
the return value of get_guest_storage_key to an unsigned char, resulting
in -EFAULT getting interpreted as a valid storage key.

Cc: stable@vger.kernel.org # 4.6+
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect that facility.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect that facility.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect if we have that facility.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect if we have the intervention bypass facility installed.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

If guest-storage-limit-suppression is not available, we would for now
have a valid guest address space with size 0. So let's simply set the
origin to 0 and the limit to hamax.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect that facility.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect the Collaborative-memory-management-interpretation facility,
aka CMM assist, so we can correctly enable cmma later.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's detect that facility, so we can correctly handle its abscence.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's correctly detect that facility, so we can correctly handle its
abscence later on.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>