The THP code in KVM/ARM is a bit restrictive in not allowing a THP
to be used if the VMA is not 2MB aligned. Actually, it is not so much
the VMA that matters, but the associated memslot:
A process can perfectly mmap a region with no particular alignment
restriction, and then pass a 2MB aligned address to KVM. In this
case, KVM will only use this 2MB aligned region, and will ignore
the range between vma->vm_start and memslot->userspace_addr.
It can also choose to place this memslot at whatever alignment it
wants in the IPA space. In the end, what matters is the relative
alignment of the user space and IPA mappings with respect to a
2M page. They absolutely must be the same if you want to use THP.
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The arch-generic KVM code expects the cpu field of a vcpu to be -1 if
the vcpu is no longer assigned to a cpu. This is used for the optimized
make_all_cpus_request path and will be used by the vgic code to check
that no vcpus are running.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Support setting the distributor and cpu interface base addresses in the
VM physical address space through the KVM_{SET,GET}_DEVICE_ATTR API
in addition to the ARM specific API.
This has the added benefit of being able to share more code in user
space and do things in a uniform manner.
Also deprecate the older API at the same time, but backwards
compatibility will be maintained.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Support creating the ARM VGIC device through the KVM_CREATE_DEVICE
ioctl, which can then later be leveraged to use the
KVM_{GET/SET}_DEVICE_ATTR, which is useful both for setting addresses in
a more generic API than the ARM-specific one and is useful for
save/restore of VGIC state.
Adds KVM_CAP_DEVICE_CTRL to ARM capabilities.
Note that we change the check for creating a VGIC from bailing out if
any VCPUs were created, to bailing out if any VCPUs were ever run. This
is an important distinction that shouldn't break anything, but allows
creating the VGIC after the VCPUs have been created.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Rework the VGIC initialization slightly to allow initialization of the
vgic cpu-specific state even if the irqchip (the VGIC) hasn't been
created by user space yet. This is safe, because the vgic data
structures are already allocated when the CPU is allocated if VGIC
support is compiled into the kernel. Further, the init process does not
depend on any other information and the sacrifice is a slight
performance degradation for creating VMs in the no-VGIC case.
The reason is that the new device control API doesn't mandate creating
the VGIC before creating the VCPU and it is unreasonable to require user
space to create the VGIC before creating the VCPUs.
At the same time move the irqchip_in_kernel check out of
kvm_vcpu_first_run_init and into the init function to make the per-vcpu
and global init functions symmetric and add comments on the exported
functions making it a bit easier to understand the init flow by only
looking at vgic.c.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
For migration to work we need to save (and later restore) the state of
each core's virtual generic timer.
Since this is per VCPU, we can use the [gs]et_one_reg ioctl and export
the three needed registers (control, counter, compare value).
Though they live in cp15 space, we don't use the existing list, since
they need special accessor functions and the arch timer is optional.
Acked-by: Marc Zynger <marc.zyngier@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Initialize the cntvoff at kvm_init_vm time, not before running the VCPUs
at the first time because that will overwrite any potentially restored
values from user space.
Cc: Andre Przywara <andre.przywara@linaro.org>
Acked-by: Marc Zynger <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The current KVM implementation of PSCI returns INVALID_PARAMETERS if the
waitqueue for the corresponding CPU is not active. This does not seem
correct, since KVM should not care what the specific thread is doing,
for example, user space may not have called KVM_RUN on this VCPU yet or
the thread may be busy looping to user space because it received a
signal; this is really up to the user space implementation. Instead we
should check specifically that the CPU is marked as being turned off,
regardless of the VCPU thread state, and if it is, we shall
simply clear the pause flag on the CPU and wake up the thread if it
happens to be blocked for us.
Further, the implementation seems to be racy when executing multiple
VCPU threads. There really isn't a reasonable user space programming
scheme to ensure all secondary CPUs have reached kvm_vcpu_first_run_init
before turning on the boot CPU.
Therefore, set the pause flag on the vcpu at VCPU init time (which can
reasonably be expected to be completed for all CPUs by user space before
running any VCPUs) and clear both this flag and the feature (in case the
feature can somehow get set again in the future) and ping the waitqueue
on turning on a VCPU using PSCI.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Upon CPU shutdown and consequent warm-reboot, the hypervisor CPU state
must be re-initialized. This patch implements a CPU PM notifier that
upon warm-boot calls a KVM hook to reinitialize properly the hypervisor
state so that the CPU can be safely resumed.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
KVM initialisation fails on architectures implementing virt_to_idmap()
because virt_to_phys() on such architectures won't fetch you the correct
idmap page.
So update the KVM ARM code to use the virt_to_idmap() to fix the issue.
Since the KVM code is shared between arm and arm64, we create
kvm_virt_to_phys() and handle the redirection in respective headers.
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Using virt_to_phys on percpu mappings is horribly wrong as it may be
backed by vmalloc. Introduce kvm_kaddr_to_phys which translates both
types of valid kernel addresses to the corresponding physical address.
At the same time resolves a typing issue where we were storing the
physical address as a 32 bit unsigned long (on arm), truncating the
physical address for addresses above the 4GB limit. This caused
breakage on Keystone.
Cc: <stable@vger.kernel.org> [3.10+]
Reported-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Pull KVM changes from Paolo Bonzini:
"Here are the 3.13 KVM changes. There was a lot of work on the PPC
side: the HV and emulation flavors can now coexist in a single kernel
is probably the most interesting change from a user point of view.
On the x86 side there are nested virtualization improvements and a few
bugfixes.
ARM got transparent huge page support, improved overcommit, and
support for big endian guests.
Finally, there is a new interface to connect KVM with VFIO. This
helps with devices that use NoSnoop PCI transactions, letting the
driver in the guest execute WBINVD instructions. This includes some
nVidia cards on Windows, that fail to start without these patches and
the corresponding userspace changes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (146 commits)
kvm, vmx: Fix lazy FPU on nested guest
arm/arm64: KVM: PSCI: propagate caller endianness to the incoming vcpu
arm/arm64: KVM: MMIO support for BE guest
kvm, cpuid: Fix sparse warning
kvm: Delete prototype for non-existent function kvm_check_iopl
kvm: Delete prototype for non-existent function complete_pio
hung_task: add method to reset detector
pvclock: detect watchdog reset at pvclock read
kvm: optimize out smp_mb after srcu_read_unlock
srcu: API for barrier after srcu read unlock
KVM: remove vm mmap method
KVM: IOMMU: hva align mapping page size
KVM: x86: trace cpuid emulation when called from emulator
KVM: emulator: cleanup decode_register_operand() a bit
KVM: emulator: check rex prefix inside decode_register()
KVM: x86: fix emulation of "movzbl %bpl, %eax"
kvm_host: typo fix
KVM: x86: emulate SAHF instruction
MAINTAINERS: add tree for kvm.git
Documentation/kvm: add a 00-INDEX file
...
A handful of fixes for KVM/arm64:
- A couple a basic fixes for running BE guests on a LE host
- A performance improvement for overcommitted VMs (same as the equivalent
patch for ARM)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Conflicts:
arch/arm/include/asm/kvm_emulate.h
arch/arm64/include/asm/kvm_emulate.h
Updates for KVM/ARM, take 3 supporting more than 4 CPUs.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Conflicts:
arch/arm/kvm/reset.c [cpu_reset->reset_regs change; context only]
When booting a vcpu using PSCI, make sure we start it with the
endianness of the caller. Otherwise, secondaries can be pretty
unhappy to execute a BE kernel in LE mode...
This conforms to PSCI spec Rev B, 5.13.3.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Do the necessary byteswap when host and guest have different
views of the universe. Actually, the only case we need to take
care of is when the guest is BE. All the other cases are naturally
handled.
Also be careful about endianness when the data is being memcopy-ed
from/to the run buffer.
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This is the ARM part of Christoph's patchset cleaning up the various
uses of __get_cpu_var across the tree.
The idea is to convert __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations
that use the offset. Thereby address calculations are avoided and fewer
registers are used when code is generated.
[will: fixed debug ref counting checks and pcpu array accesses]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Updates for KVM/ARM, take 2 including:
- Transparent Huge Pages and hugetlbfs support for KVM/ARM
- Yield CPU when guest executes WFE to speed up CPU overcommit
The KVM PSCI code blindly assumes that vcpu_id and MPIDR are
the same thing. This is true when vcpus are organized as a flat
topology, but is wrong when trying to emulate any other topology
(such as A15 clusters).
Change the KVM PSCI CPU_ON code to look at the MPIDR instead
of the vcpu_id to pick a target CPU.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Now that the KVM/arm code knows about affinity, remove the hard
limit of 4 vcpus per VM.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The L2CTLR register contains the number of CPUs in this cluster.
Make sure the register content is actually relevant to the vcpu
that is being configured by computing the number of cores that are
part of its cluster.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
In order to be able to support more than 4 A7 or A15 CPUs,
we need to fix the MPIDR computing to reflect the fact that
both A15 and A7 can only exist in clusters of at most 4 CPUs.
Fix the MPIDR computing to allow virtual clusters to be exposed
to the guest.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Support transparent huge pages in KVM/ARM and KVM/ARM64. The
transparent_hugepage_adjust is not very pretty, but this is also how
it's solved on x86 and seems to be simply an artifact on how THPs
behave. This should eventually be shared across architectures if
possible, but that can always be changed down the road.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Support huge pages in KVM/ARM and KVM/ARM64. The pud_huge checking on
the unmap path may feel a bit silly as the pud_huge check is always
defined to false, but the compiler should be smart about this.
Note: This deals only with VMAs marked as huge which are allocated by
users through hugetlbfs only. Transparent huge pages can only be
detected by looking at the underlying pages (or the page tables
themselves) and this patch so far simply maps these on a page-by-page
level in the Stage-2 page tables.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Update comments to reflect what is really going on and add the TWE bit
to the comments in kvm_arm.h.
Also renames the function to kvm_handle_wfx like is done on arm64 for
consistency and uber-correctness.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
On an (even slightly) oversubscribed system, spinlocks are quickly
becoming a bottleneck, as some vcpus are spinning, waiting for a
lock to be released, while the vcpu holding the lock may not be
running at all.
This creates contention, and the observed slowdown is 40x for
hackbench. No, this isn't a typo.
The solution is to trap blocking WFEs and tell KVM that we're
now spinning. This ensures that other vpus will get a scheduling
boost, allowing the lock to be released more quickly. Also, using
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT slightly improves the performance
when the VM is severely overcommited.
Quick test to estimate the performance: hackbench 1 process 1000
2xA15 host (baseline): 1.843s
2xA15 guest w/o patch: 2.083s
4xA15 guest w/o patch: 80.212s
8xA15 guest w/o patch: Could not be bothered to find out
2xA15 guest w/ patch: 2.102s
4xA15 guest w/ patch: 3.205s
8xA15 guest w/ patch: 6.887s
So we go from a 40x degradation to 1.5x in the 2x overcommit case,
which is vaguely more acceptable.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This patch adds support for running Cortex-A7 guests on Cortex-A7 hosts.
As Cortex-A7 is architecturally compatible with A15, this patch is largely just
generalising existing code. Areas where 'implementation defined' behaviour
is identical for A7 and A15 is moved to allow it to be used by both cores.
The check to ensure that coprocessor register tables are sorted correctly is
also moved in to 'common' code to avoid each new cpu doing its own check
(and possibly forgetting to do so!)
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
KVM does not have a notion of multiple clusters for CPUs, just a linear
array of CPUs. When using a system with cores in more than one cluster, the
current method for calculating the virtual MPIDR will leak the (physical)
cluster information into the virtual MPIDR. One effect of this is that
Linux under KVM fails to boot multiple CPUs that aren't in the 0th cluster.
This patch does away with exposing the real MPIDR fields in favour of simply
using the virtual CPU number (but preserving the U bit, as before).
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
For implementing CPU=host, we need a mechanism for querying
preferred VCPU target type on underlying Host.
This patch implements KVM_ARM_PREFERRED_TARGET vm ioctl which
returns struct kvm_vcpu_init instance containing information
about preferred VCPU target type and target specific features
available for it.
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This patch implements kvm_vcpu_preferred_target() function for
KVM ARM which will help us implement KVM_ARM_PREFERRED_TARGET ioctl
for user space.
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Very minor typo in comments of inject_abt() when we update fault status
register for injecting prefetch abort.
Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Pull ARM updates from Russell King:
"This set includes adding support for Neon acceleration of RAID6 XOR
code from Ard Biesheuvel, cache flushing and barrier updates from Will
Deacon, and a cleanup to the ARM debug code which reduces the amount
of code by about 500 lines.
A few other cleanups, such as constifying the machine descriptors
which already shouldn't be written to, cleaning up the printing of the
L2 cache size"
* 'for-linus' of git://git.linaro.org/people/rmk/linux-arm: (55 commits)
ARM: 7826/1: debug: support debug ll on hisilicon soc
ARM: 7830/1: delay: don't bother reporting bogomips in /proc/cpuinfo
ARM: 7829/1: Add ".text.unlikely" and ".text.hot" to arm unwind tables
ARM: 7828/1: ARMv7-M: implement restart routine common to all v7-M machines
ARM: 7827/1: highbank: fix debug uart virtual address for LPAE
ARM: 7823/1: errata: workaround Cortex-A15 erratum 773022
ARM: 7806/1: allow DEBUG_UNCOMPRESS for Tegra
ARM: 7793/1: debug: use generic option for ep93xx PL10x debug port
ARM: debug: move SPEAr debug to generic PL01x code
ARM: debug: move davinci debug to generic 8250 code
ARM: debug: move keystone debug to generic 8250 code
ARM: debug: remove DEBUG_ROCKCHIP_UART
ARM: debug: provide generic option choices for 8250 and PL01x ports
ARM: debug: move PL01X debug include into arch/arm/include/debug/
ARM: debug: provide PL01x debug uart phys/virt address configuration options
ARM: debug: add support for word accesses to debug/8250.S
ARM: debug: move 8250 debug include into arch/arm/include/debug/
ARM: debug: provide 8250 debug uart phys/virt address configuration options
ARM: debug: provide 8250 debug uart register shift configuration option
ARM: debug: provide 8250 debug uart flow control configuration option
...
Pull KVM updates from Gleb Natapov:
"The highlights of the release are nested EPT and pv-ticketlocks
support (hypervisor part, guest part, which is most of the code, goes
through tip tree). Apart of that there are many fixes for all arches"
Fix up semantic conflicts as discussed in the pull request thread..
* 'next' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (88 commits)
ARM: KVM: Add newlines to panic strings
ARM: KVM: Work around older compiler bug
ARM: KVM: Simplify tracepoint text
ARM: KVM: Fix kvm_set_pte assignment
ARM: KVM: vgic: Bump VGIC_NR_IRQS to 256
ARM: KVM: Bugfix: vgic_bytemap_get_reg per cpu regs
ARM: KVM: vgic: fix GICD_ICFGRn access
ARM: KVM: vgic: simplify vgic_get_target_reg
KVM: MMU: remove unused parameter
KVM: PPC: Book3S PR: Rework kvmppc_mmu_book3s_64_xlate()
KVM: PPC: Book3S PR: Make instruction fetch fallback work for system calls
KVM: PPC: Book3S PR: Don't corrupt guest state when kernel uses VMX
KVM: x86: update masterclock when kvmclock_offset is calculated (v2)
KVM: PPC: Book3S: Fix compile error in XICS emulation
KVM: PPC: Book3S PR: return appropriate error when allocation fails
arch: powerpc: kvm: add signed type cast for comparation
KVM: x86: add comments where MMIO does not return to the emulator
KVM: vmx: count exits to userspace during invalid guest emulation
KVM: rename __kvm_io_bus_sort_cmp to kvm_io_bus_cmp
kvm: optimize away THP checks in kvm_is_mmio_pfn()
...
The panic strings are hard to read and on narrow terminals some
characters are simply truncated off the panic message.
Make is slightly prettier with a newline in the Hyp panic strings.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
THe L_PTE_USER actually has nothing to do with stage 2 mappings and the
L_PTE_S2_RDWR value sets the readable bit, which was what L_PTE_USER
was used for before proper handling of stage 2 memory defines.
Changelog:
[v3]: Drop call to kvm_set_s2pte_writable in mmu.c
[v2]: Change default mappings to be r/w instead of r/o, as per Marc
Zyngier's suggestion.
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
When flushing the TLB at PL2 in response to remapping at stage-2 or VMID
rollover, we have a dsb instruction to ensure completion of the command
before continuing.
Since we only care about other processors for TLB invalidation, use the
inner-shareable variant of the dsb instruction instead.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The 'len' variable was declared an unsigned and then checked for less
than 0, which results in warnings on some compilers. Since len is
assigned an int, make it an int.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
When using 64kB pages, we only have two levels of page tables,
meaning that PGD, PUD and PMD are fused. In this case, trying
to refcount PUDs and PMDs independently is a a complete disaster,
as they are the same.
We manage to get it right for the allocation (stage2_set_pte uses
{pmd,pud}_none), but the unmapping path clears both pud and pmd
refcounts, which fails spectacularly with 2-level page tables.
The fix is to avoid calling clear_pud_entry when both the pmd and
pud pages are empty. For this, and instead of introducing another
pud_empty function, consolidate both pte_empty and pmd_empty into
page_empty (the code is actually identical) and use that to also
test the validity of the pud.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The unmap_range function did not properly cover the case when the start
address was not aligned to PMD_SIZE or PUD_SIZE and an entire pte table
or pmd table was cleared, causing us to leak memory when incrementing
the addr.
The fix is to always move onto the next page table entry boundary
instead of adding the full size of the VA range covered by the
corresponding table level entry.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
The PAR was exported as CRn == 7 and CRm == 0, but in fact the primary
coprocessor register number was determined by CRm for 64-bit coprocessor
registers as the user space API was modeled after the coprocessor
access instructions (see the ARM ARM rev. C - B3-1445).
However, just changing the CRn to CRm breaks the sorting check when
booting the kernel, because the internal kernel logic always treats CRn
as the primary register number, and it makes the table sorting
impossible to understand for humans.
Alternatively we could change the logic to always have CRn == CRm, but
that becomes unclear in the number of ways we do look up of a coprocessor
register. We could also have a separate 64-bit table but that feels
somewhat over-engineered. Instead, keep CRn the primary representation
of the primary coproc. register number in-kernel and always export the
primary number as CRm as per the existing user space ABI.
Note: The TTBR registers just magically worked because they happened to
follow the CRn(0) regs and were considered CRn(0) in the in-kernel
representation.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
