Add new entry point to scan the device tree at boot in a guest,
looking for cxl devices.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The new flash.c file contains the logic to flash a new image on the
adapter, through a hcall. It is an iterative process, with chunks of
data of 1M at a time. There are also 2 phases: write and verify. The
flash operation itself is driven from a user-land tool.
Once flashing is successful, an rtas call is made to update the device
tree with the new properties values for the adapter and the AFU(s)

Add a new char device for the adapter, so that the flash tool can
access the card, even if there is no valid AFU on it.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Filter out a few adapter parameters which don't make sense in a guest.
Document the changes.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The new of.c file contains code to parse the device tree to find out
about cxl adapters and AFUs.

guest.c implements the guest-specific callbacks for the backend API.

The process element ID is not known until the context is attached, so
we have to separate the context ID assigned by the cxl driver from the
process element ID visible to the user applications. In bare-metal,
the 2 IDs match.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
[mpe: Fix SMP=n build, fix PSERIES=n build, minor whitespace fixes]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Introduce sub-structures containing the bare-metal specific fields in
the structures describing the adapter (struct cxl) and AFU (struct
cxl_afu).
Update all their references.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The hypervisor calls provide an interface with a coherent platform
facility and function. It matches version 0.16 of the 'PAPR changes'
document.

The following hcalls are supported:
H_ATTACH_CA_PROCESS    Attach a process element to a coherent platform
                       function.
H_DETACH_CA_PROCESS    Detach a process element from a coherent
                       platform function.
H_CONTROL_CA_FUNCTION  Allow the partition to manipulate or query
                       certain coherent platform function behaviors.
H_COLLECT_CA_INT_INFO  Collect interrupt info about a coherent.
                       platform function after an interrupt occurred
H_CONTROL_CA_FAULTS    Control the operation of a coherent platform
                       function after a fault occurs.
H_DOWNLOAD_CA_FACILITY Support for downloading a base adapter image to
                       the coherent platform facility, and for
                       validating the entire image after the download.
H_CONTROL_CA_FACILITY  Allow the partition to manipulate or query
                       certain coherent platform facility behaviors.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The hcalls introduced for cxl use a possible new value:
H_STATE (invalid state).
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The PSL interrupt cannot be multiplexed in a guest, as it is not
supported by the hypervisor. So an interrupt will be allocated
for it for each context. It will still be the first interrupt found in
the first interrupt range, but is treated almost like any other AFU
interrupt when creating/deleting the context. Only the handler is
different. Rework the code so that the range 0 is treated like the
other ranges.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The context parameter when calling cxl_irq() should be strongly typed.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

A few functions are mostly common between bare-metal and guest and
just need minor tuning. To avoid crowding the backend API, introduce a
few 'if' based on the CPU being in HV mode.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Rename a few functions, changing the 'cxl_' prefix to either
'cxl_pci_' or 'cxl_native_', to make clear that the implementation is
bare-metal specific.

Those functions will have an equivalent implementation for a guest in
a later patch.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The backend API (in cxl.h) lists some low-level functions whose
implementation is different on bare-metal and in a guest. Each
environment implements its own functions, and the common code uses
them through function pointers, defined in cxl_backend_ops
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

CXL kernel API was defining the process problem state area during
context initialization, making it possible to map the problem state
area before attaching the context. This won't work on a powerVM
guest. So force the logical behavior, like in userspace: attach first,
then map the problem state area.
Remove calls to cxl_assign_psn_space during init. The function is
already called on the attach paths.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Move a few functions around to better separate code specific to
bare-metal environment from code which will be commonly used between
guest and bare-metal.

Code specific to bare-metal is meant to be in native.c or pci.c
only. It's basically anything which touches the card p1 registers,
some p2 registers not needed from a guest and the PCI interface.
Co-authored-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Move around some functions which will be accessed from the bare-metal
and guest environments.
Code in native.c and pci.c is meant to be bare-metal specific.
Other files contain code which may be shared with guests.
Co-authored-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: NChristophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: NManoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

In eeh_pci_enable(), after making the request to set the new options, we
call eeh_ops->wait_state() to check that the request finished successfully.

At the moment, if eeh_ops->wait_state() returns 0, we return 0 without
checking that it reflects the expected outcome. This can lead to callers
further up the chain incorrectly assuming the slot has been successfully
unfrozen and continuing to attempt recovery.

On powernv, this will occur if pnv_eeh_get_pe_state() or
pnv_eeh_get_phb_state() return 0, which in turn occurs if the relevant OPAL
call returns OPAL_EEH_STOPPED_MMIO_DMA_FREEZE or
OPAL_EEH_PHB_ERROR respectively.

On pseries, this will occur if pseries_eeh_get_state() returns 0, which in
turn occurs if RTAS reports that the PE is in the MMIO Stopped and DMA
Stopped states.

Obviously, none of these cases represent a successful completion of a
request to thaw MMIO or DMA.

Fix the check so that a wait_state() return value of 0 won't be considered
successful for the EEH_OPT_THAW_MMIO or EEH_OPT_THAW_DMA cases.
Signed-off-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NDaniel Axtens <dja@axtens.net>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

When eeh_dump_pe_log() is only called by eeh_slot_error_detail(),
we already have the check that the PE isn't in PCI config blocked
state in eeh_slot_error_detail(). So we needn't the duplicated
check in eeh_dump_pe_log().

This removes the duplicated check in eeh_dump_pe_log(). No logical
changes introduced.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

When passing through SRIOV VFs to guest, we possibly encounter EEH
error on PF. In this case, the VF PEs are put into frozen state.
The error could be reported to guest before it's captured by the
host. That means the guest could attempt to recover errors on VFs
before host gets chance to recover errors on PFs. The VFs won't be
recovered successfully.

This enforces the recovery order for above case: the recovery on
child PE in guest is hold until the recovery on parent PE in host
is completed.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NRussell Currey <ruscur@russell.cc>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

When we have partial hotplug as part of the error recovery on PF,
the VFs that are bound with vfio-pci driver will experience hotplug.
That's not allowed.

This checks if the VF PE is passed or not. If it does, we leave
the VF without removing it.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NRussell Currey <ruscur@russell.cc>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

When EEH error happened to the parent PE of those PEs that have
been passed through to guest, the error is propagated to guest
domain and the VFIO driver's error handlers are called. It's not
correct as the error in the host domain shouldn't be propagated
to guests and affect them.

This adds one more limitation when calling EEH error handlers.
If the PE has been passed through to guest, the error handlers
won't be called.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NRussell Currey <ruscur@russell.cc>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

PFs are enumerated on PCI bus, while VFs are created by PF's driver.

In EEH recovery, it has two cases:
1. Device and driver is EEH aware, error handlers are called.
2. Device and driver is not EEH aware, un-plug the device and plug it again
by enumerating it.

The special thing happens on the second case. For a PF, we could use the
original pci core to enumerate the bus, while for VF we need to record the
VFs which aer un-plugged then plug it again.

Also The patch caches the VF index in pci_dn, which can be used to
calculate VF's bus, device and function number. Those information helps to
locate the VF's PCI device instance when doing hotplug during EEH recovery
if necessary.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

After PE reset, OPAL API opal_pci_reinit() is called on all devices
contained in the PE to reinitialize them. While skiboot is not aware of
VFs, we have to implement the function in kernel to reinitialize VFs after
reset on PE for VFs.

In this patch, two functions pnv_pci_fixup_vf_mps() and
pnv_eeh_restore_vf_config() both manipulate the MPS of the VF, since for a
VF it has three cases.

1. Normal creation for a VF
   In this case, pnv_pci_fixup_vf_mps() is called to make the MPS a proper
   value compared with its parent.
2. EEH recovery without VF removed
   In this case, MPS is stored in pci_dn and pnv_eeh_restore_vf_config() is
   called to restore it and reinitialize other part.
3. EEH recovery with VF removed
   In this case, VF will be removed then re-created. Both functions are
   called. First pnv_pci_fixup_vf_mps() is called to store the proper MPS
   to pci_dn and then pnv_eeh_restore_vf_config() is called to do proper
   thing.

This introduces two functions: pnv_pci_fixup_vf_mps() to fixup the VF's
MPS to make sure it is equal to parent's and store this value in pci_dn
for future use. pnv_eeh_restore_vf_config() to re-initialize on VF by
restoring MPS, disabling completion timeout, enabling SERR, etc.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

PEs for VFs don't have primary bus. So they have to have their own reset
backend, which is used during EEH recovery. The patch implements the reset
backend for VF's PE by issuing FLR or AF FLR to the VFs, which are contained
in the PE.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This creates PEs for VFs in the weak function pcibios_bus_add_device().
Those PEs for VFs are identified with newly introduced flag EEH_PE_VF
so that we treat them differently during EEH recovery.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

VFs and their corresponding pdn are created and released dynamically
when their PF's SRIOV capability is enabled and disabled. This creates
and releases EEH devices for VFs when creating and releasing their pdn
instances, which means EEH devices and pdn instances have same life
cycle. Also, VF's EEH device is identified by (struct eeh_dev::physfn).
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This restricts the EEH address cache to use only the first 7 BARs. This
makes __eeh_addr_cache_insert_dev() ignore PCI bridge window and IOV BARs.
As the result of this change, eeh_addr_cache_get_dev() will return VFs from
VF's resource addresses instead of parent PFs.

This also removes PCI bridge check as we limit __eeh_addr_cache_insert_dev()
to 7 BARs and this effectively excludes PCI bridges from being cached.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

As commit ac205b7b ("PCI: make sriov work with hotplug remove")
indicates, VFs which is on the same PCI bus as their PF, should be
removed before the PF. Otherwise, we might run into kernel crash
at PCI unplugging time.

This applies the above pattern to powerpc PCI hotplug path.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This adds weak function pcibios_bus_add_device() for arch dependent
code could do proper setup. For example, powerpc could setup EEH
related resources for SRIOV VFs.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Reviewed-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

During EEH recovery, hotplug is applied to the devices which don't
have drivers or their drivers don't support EEH. However, the hotplug,
which was implemented based on PCI bus, can't be applied to VF directly.
Instead, we unplug and plug individual PCI devices (VFs).

This renames virtn_{add,remove}() and exports them so they can be used
in PCI hotplug during EEH recovery.
Signed-off-by: NWei Yang <weiyang@linux.vnet.ibm.com>
Reviewed-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The original implementation is ugly: unnecessary if statements and
"out" tag. This reworks the function to avoid above weaknesses. No
functional changes introduced.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

No code changes.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

No code changes.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We don't need to update linux page table entry with _PAGE_HASHPTE early
in hash pte fault. A parallel pte update will loop via _PAGE_BUSY
and look at _PAGE_HASHPTE for a required hpte flush only if
_PAGE_BUSY is cleared. That ensures a pte update will wait for a
parallel hpte insert to finish before looking at _PAGE_HASHPTE bit.

To avoid further confusion drop setting _PAGE_HASHPTE in cmpxchg in __hash_page_4K.

commit 41743a4e ("powerpc: Free a PTE bit on ppc64 with 64K pages")
did similar change for 64K config
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We are updating pte in those functions.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

With next generation power processor, we are having a new mmu model
[1] that require us to maintain a different linux page table format.

Inorder to support both current and future ppc64 systems with a single
kernel we need to make sure kernel can select between different page
table format at runtime. With the new MMU (radix MMU) added, we will
have two different pmd hugepage size 16MB for hash model and 2MB for
Radix model. Hence make HPAGE_PMD related values as a variable.

Actual conversion of HPAGE_PMD to a variable for ppc64 happens in a
followup patch.

[1] http://ibm.biz/power-isa3 (Needs registration).
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This is needed so that we can support both hash and radix page table
using single kernel. Radix kernel uses a 4 level table.

We now use physical address in upper page table tree levels. Even though
they are aligned to their size, for the masked bits we use the
bit positions as per PowerISA 3.0.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We remove real_pte_t out of STRICT_MM_TYPESCHECK.
Reviewed-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We move the page table accessors into a separate header. We will
later add a big endian variant of the table which is needed for radix.
No functionality change only code movement.
Reviewed-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This patch adds the ability to be able to save the VSX registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.
Signed-off-by: NCyril Bur <cyrilbur@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This patch adds the ability to be able to save the VEC registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU registers in the
thread copy path to avoid a possibly pointless reload of VEC state.
Signed-off-by: NCyril Bur <cyrilbur@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>