Currently we have struct kvm_exit_mmio for encapsulating MMIO abort
data to be passed on from syndrome decoding all the way down to the
VGIC register handlers. Now as we switch the MMIO handling to be
routed through the KVM MMIO bus, it does not make sense anymore to
use that structure already from the beginning. So we keep the data in
local variables until we put them into the kvm_io_bus framework.
Then we fill kvm_exit_mmio in the VGIC only, making it a VGIC private
structure. On that way we replace the data buffer in that structure
with a pointer pointing to a single location in a local variable, so
we get rid of some copying on the way.
With all of the virtual GIC emulation code now being registered with
the kvm_io_bus, we can remove all of the old MMIO handling code and
its dispatching functionality.

I didn't bother to rename kvm_exit_mmio (to vgic_mmio or something),
because that touches a lot of code lines without any good reason.

This is based on an original patch by Nikolay.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Cc: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Currently we use a lot of VGIC specific code to do the MMIO
dispatching.
Use the previous reworks to add kvm_io_bus style MMIO handlers.

Those are not yet called by the MMIO abort handler, also the actual
VGIC emulator function do not make use of it yet, but will be enabled
with the following patches.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

The vgic_find_range() function in vgic.c takes a struct kvm_exit_mmio
argument, but actually only used the length field in there. Since we
need to get rid of that structure in that part of the code anyway,
let's rework the function (and it's callers) to pass the length
argument to the function directly.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

The name "kvm_mmio_range" is a bit bold, given that it only covers
the VGIC's MMIO ranges. To avoid confusion with kvm_io_range, rename
it to vgic_io_range.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Migrating active interrupts causes the active state to be lost
completely. This implements some additional bitmaps to track the active
state on the distributor and export this to user space.
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

This helps re-factor away some of the repetitive code and makes the code
flow more nicely.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

This patch enables irqfd on arm/arm64.

Both irqfd and resamplefd are supported. Injection is implemented
in vgic.c without routing.

This patch enables CONFIG_HAVE_KVM_EVENTFD and CONFIG_HAVE_KVM_IRQFD.

KVM_CAP_IRQFD is now advertised. KVM_CAP_IRQFD_RESAMPLE capability
automatically is advertised as soon as CONFIG_HAVE_KVM_IRQFD is set.

Irqfd injection is restricted to SPI. The rationale behind not
supporting PPI irqfd injection is that any device using a PPI would
be a private-to-the-CPU device (timer for instance), so its state
would have to be context-switched along with the VCPU and would
require in-kernel wiring anyhow. It is not a relevant use case for
irqfds.
Signed-off-by: NEric Auger <eric.auger@linaro.org>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

To prepare for irqfd addition, coarse grain locking is removed at
kvm_vgic_sync_hwstate level and finer grain locking is introduced in
vgic_process_maintenance only.
Signed-off-by: NEric Auger <eric.auger@linaro.org>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Several dts only list "arm,cortex-a7-gic" or "arm,gic-400" in their GIC
compatible list, and while this is correct (and supported by the GIC
driver), KVM will fail to detect that it can support these cases.

This patch adds the missing strings to the VGIC code. The of_device_id
entries are padded to keep the probe function data aligned.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Michal Simek <monstr@monstr.eu>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Although the GIC architecture requires us to map the MMIO regions
only at page aligned addresses, we currently do not enforce this from
the kernel side.
Restrict any vGICv2 regions to be 4K aligned and any GICv3 regions
to be 64K aligned. Document this requirement.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

With all of the GICv3 code in place now we allow userland to ask the
kernel for using a virtual GICv3 in the guest.
Also we provide the necessary support for guests setting the memory
addresses for the virtual distributor and redistributors.
This requires some userland code to make use of that feature and
explicitly ask for a virtual GICv3.
Document that KVM_CREATE_IRQCHIP only works for GICv2, but is
considered legacy and using KVM_CREATE_DEVICE is preferred.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

With all the necessary GICv3 emulation code in place, we can now
connect the code to the GICv3 backend in the kernel.
The LR register handling is different depending on the emulated GIC
model, so provide different implementations for each.
Also allow non-v2-compatible GICv3 implementations (which don't
provide MMIO regions for the virtual CPU interface in the DT), but
restrict those hosts to support GICv3 guests only.
If the device tree provides a GICv2 compatible GICV resource entry,
but that one is faulty, just disable the GICv2 emulation and let the
user use at least the GICv3 emulation for guests.
To provide proper support for the legacy KVM_CREATE_IRQCHIP ioctl,
note virtual GICv2 compatibility in struct vgic_params and use it
on creating a VGICv2.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

With everything separated and prepared, we implement a model of a
GICv3 distributor and redistributors by using the existing framework
to provide handler functions for each register group.

Currently we limit the emulation to a model enforcing a single
security state, with SRE==1 (forcing system register access) and
ARE==1 (allowing more than 8 VCPUs).

We share some of the functions provided for GICv2 emulation, but take
the different ways of addressing (v)CPUs into account.
Save and restore is currently not implemented.

Similar to the split-off of the GICv2 specific code, the new emulation
code goes into a new file (vgic-v3-emul.c).
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

For a GICv2 there is always only one (v)CPU involved: the one that
does the access. On a GICv3 the access to a CPU redistributor is
memory-mapped, but not banked, so the (v)CPU affected is determined by
looking at the MMIO address region being accessed.
To allow passing the affected CPU into the accessors later, extend
struct kvm_exit_mmio to add an opaque private pointer parameter.
The current GICv2 emulation just does not use it.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

vgic.c is currently a mixture of generic vGIC emulation code and
functions specific to emulating a GICv2. To ease the addition of
GICv3, split off strictly v2 specific parts into a new file
vgic-v2-emul.c.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>

-------
As the diff isn't always obvious here (and to aid eventual rebases),
here is a list of high-level changes done to the code:
* added new file to respective arm/arm64 Makefiles
* moved GICv2 specific functions to vgic-v2-emul.c:
  - handle_mmio_misc()
  - handle_mmio_set_enable_reg()
  - handle_mmio_clear_enable_reg()
  - handle_mmio_set_pending_reg()
  - handle_mmio_clear_pending_reg()
  - handle_mmio_priority_reg()
  - vgic_get_target_reg()
  - vgic_set_target_reg()
  - handle_mmio_target_reg()
  - handle_mmio_cfg_reg()
  - handle_mmio_sgi_reg()
  - vgic_v2_unqueue_sgi()
  - read_set_clear_sgi_pend_reg()
  - write_set_clear_sgi_pend_reg()
  - handle_mmio_sgi_set()
  - handle_mmio_sgi_clear()
  - vgic_v2_handle_mmio()
  - vgic_get_sgi_sources()
  - vgic_dispatch_sgi()
  - vgic_v2_queue_sgi()
  - vgic_v2_map_resources()
  - vgic_v2_init()
  - vgic_v2_add_sgi_source()
  - vgic_v2_init_model()
  - vgic_v2_init_emulation()
  - handle_cpu_mmio_misc()
  - handle_mmio_abpr()
  - handle_cpu_mmio_ident()
  - vgic_attr_regs_access()
  - vgic_create() (renamed to vgic_v2_create())
  - vgic_destroy() (renamed to vgic_v2_destroy())
  - vgic_has_attr() (renamed to vgic_v2_has_attr())
  - vgic_set_attr() (renamed to vgic_v2_set_attr())
  - vgic_get_attr() (renamed to vgic_v2_get_attr())
  - struct kvm_mmio_range vgic_dist_ranges[]
  - struct kvm_mmio_range vgic_cpu_ranges[]
  - struct kvm_device_ops kvm_arm_vgic_v2_ops {}
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

vgic.c is currently a mixture of generic vGIC emulation code and
functions specific to emulating a GICv2. To ease the addition of
GICv3 later, we create new header file vgic.h, which holds constants
and prototypes of commonly used functions.
Rename some identifiers to avoid name space clutter.
I removed the long-standing comment about using the kvm_io_bus API
to tackle the GIC register ranges, as it wouldn't be a win for us
anymore.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>

-------
As the diff isn't always obvious here (and to aid eventual rebases),
here is a list of high-level changes done to the code:
* moved definitions and prototypes from vgic.c to vgic.h:
  - VGIC_ADDR_UNDEF
  - ACCESS_{READ,WRITE}_*
  - vgic_init()
  - vgic_update_state()
  - vgic_kick_vcpus()
  - vgic_get_vmcr()
  - vgic_set_vmcr()
  - struct mmio_range {} (renamed to struct kvm_mmio_range)
* removed static keyword and exported prototype in vgic.h:
  - vgic_bitmap_get_reg()
  - vgic_bitmap_set_irq_val()
  - vgic_bitmap_get_shared_map()
  - vgic_bytemap_get_reg()
  - vgic_dist_irq_set_pending()
  - vgic_dist_irq_clear_pending()
  - vgic_cpu_irq_clear()
  - vgic_reg_access()
  - handle_mmio_raz_wi()
  - vgic_handle_enable_reg()
  - vgic_handle_set_pending_reg()
  - vgic_handle_clear_pending_reg()
  - vgic_handle_cfg_reg()
  - vgic_unqueue_irqs()
  - find_matching_range() (renamed to vgic_find_range)
  - vgic_handle_mmio_range()
  - vgic_update_state()
  - vgic_get_vmcr()
  - vgic_set_vmcr()
  - vgic_queue_irq()
  - vgic_kick_vcpus()
  - vgic_init()
  - vgic_v2_init_emulation()
  - vgic_has_attr_regs()
  - vgic_set_common_attr()
  - vgic_get_common_attr()
  - vgic_destroy()
  - vgic_create()
* moved functions to vgic.h (static inline):
  - mmio_data_read()
  - mmio_data_write()
  - is_in_range()
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

vgic_set_attr() and vgic_get_attr() contain both code specific for
the emulated GIC as well as code for the userland facing, generic
part of the GIC.
Split the guest GIC facing code of from the generic part to allow
easier splitting later.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The MMIO accessors for GICD_I[CS]ENABLER, GICD_I[CS]PENDR and
GICD_ICFGR behave very similar for GICv2 and GICv3, although the way
the affected VCPU is determined differs.
Since we need them to access the registers from three different
places in the future, we factor out a generic, backend-facing
implementation and use small wrappers in the current GICv2 emulation.
This will ease adding GICv3 accessors later.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Currently the maximum number of vCPUs supported is a global value
limited by the used GIC model. GICv3 will lift this limit, but we
still need to observe it for guests using GICv2.
So the maximum number of vCPUs is per-VM value, depending on the
GIC model the guest uses.
Store and check the value in struct kvm_arch, but keep it down to
8 for now.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

To check whether the vGIC was already initialized, we currently check
the GICH base address for not being NULL. Since with GICv3 we may
get along without this address, lets use the irqchip_in_kernel()
function to detect an already initialized vGIC.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Currently we unconditionally register the GICv2 emulation device
during the host's KVM initialization. Since with GICv3 support we
may end up with only v2 or only v3 or both supported, we move the
registration into the GIC probing function, where we will later know
which combination is valid.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Currently we only have one virtual GIC model supported, so all guests
use the same emulation code. With the addition of another model we
end up with different guests using potentially different vGIC models,
so we have to split up some functions to be per VM.
Introduce a vgic_vm_ops struct to hold function pointers for those
functions that are different and provide the necessary code to
initialize them.
Also split up the vgic_init() function to separate out VGIC model
specific functionality into a separate function, which will later be
different for a GICv3 model.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Some GICv3 registers can and will be accessed as 64 bit registers.
Currently the register handling code can only deal with 32 bit
accesses, so we do two consecutive calls to cover this.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Currently we only need to deal with one MMIO region for the GIC
emulation (the GICv2 distributor), but we soon need to extend this.
Refactor the existing code to allow easier addition of different
ranges without code duplication.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

With the introduction of a second emulated GIC model we need to let
userspace specify the GIC model to use for each VM. Pass the
userspace provided value down into the vGIC code and store it there
to differentiate later.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Since the advent of VGIC dynamic initialization, this latter is
initialized quite late on the first vcpu run or "on-demand", when
injecting an IRQ or when the guest sets its registers.

This initialization could be initiated explicitly much earlier
by the users-space, as soon as it has provided the requested
dimensioning parameters.

This patch adds a new entry to the VGIC KVM device that allows
the user to manually request the VGIC init:
- a new KVM_DEV_ARM_VGIC_GRP_CTRL group is introduced.
- Its first attribute is KVM_DEV_ARM_VGIC_CTRL_INIT

The rationale behind introducing a group is to be able to add other
controls later on, if needed.
Signed-off-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

To be more explicit on vgic initialization failure, -ENODEV is
returned by vgic_init when no online vcpus can be found at init.
Signed-off-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Userspace assumes that it can wire up IRQ injections after having
created all VCPUs and after having created the VGIC, but potentially
before starting the first VCPU.  This can currently lead to lost IRQs
because the state of that IRQ injection is not stored anywhere and we
don't return an error to userspace.

We haven't seen this problem manifest itself yet, presumably because
guests reset the devices on boot, but this could cause issues with
migration and other non-standard startup configurations.
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Some code paths will need to check to see if the internal state of the
vgic has been initialized (such as when creating new VCPUs), so
introduce such a macro that checks the nr_cpus field which is set when
the vgic has been initialized.

Also set nr_cpus = 0 in kvm_vgic_destroy, because the error path in
vgic_init() will call this function, and code should never errornously
assume the vgic to be properly initialized after an error.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The vgic_initialized() macro currently returns the state of the
vgic->ready flag, which indicates if the vgic is ready to be used when
running a VM, not specifically if its internal state has been
initialized.

Rename the macro accordingly in preparation for a more nuanced
initialization flow.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

VGIC initialization currently happens in three phases:
 (1) kvm_vgic_create() (triggered by userspace GIC creation)
 (2) vgic_init_maps() (triggered by userspace GIC register read/write
     requests, or from kvm_vgic_init() if not already run)
 (3) kvm_vgic_init() (triggered by first VM run)

We were doing initialization of some state to correspond with the
state of a freshly-reset GIC in kvm_vgic_init(); this is too late,
since it will overwrite changes made by userspace using the
register access APIs before the VM is run. Move this initialization
earlier, into the vgic_init_maps() phase.

This fixes a bug where QEMU could successfully restore a saved
VM state snapshot into a VM that had already been run, but could
not restore it "from cold" using the -loadvm command line option
(the symptoms being that the restored VM would run but interrupts
were ignored).

Finally rename vgic_init_maps to vgic_init and renamed kvm_vgic_init to
kvm_vgic_map_resources.

  [ This patch is originally written by Peter Maydell, but I have
    modified it somewhat heavily, renaming various bits and moving code
    around.  If something is broken, I am to be blamed. - Christoffer ]
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NEric Auger <eric.auger@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

If we detect another vCPU is running we just exit and return 0 as if we
succesfully created the VGIC, but the VGIC wouldn't actual be created.

This shouldn't break in-kernel behavior because the kernel will not
observe the failed the attempt to create the VGIC, but userspace could
be rightfully confused.

Cc: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When call kvm_vgic_inject_irq to inject interrupt, we can known which
vcpu the interrupt for by the irq_num and the cpuid. So we should just
kick this vcpu to avoid iterating through all.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NShannon Zhao <zhaoshenglong@huawei.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

When 'injecting' an edge-triggered interrupt with a falling edge we
shouldn't clear the pending state on the distributor.  In fact, we
don't, because the check in vgic_validate_injection would prevent us
from ever reaching this bit of code.

Remove the unreachable snippet.
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

When vgic_update_irq_pending with level-sensitive false, it is need to
deactivates an interrupt, and, it can go to out directly.
Here return a false value, because it will be not need to kick.
Signed-off-by: Nwanghaibin <wanghaibin.wang@huawei.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

The EIRSR and ELRSR registers are 32-bit registers on GICv2, and we
store these as an array of two such registers on the vgic vcpu struct.
However, we access them as a single 64-bit value or as a bitmap pointer
in the generic vgic code, which breaks BE support.

Instead, store them as u64 values on the vgic structure and do the
word-swapping in the assembly code, which already handles the byte order
for BE systems.
Tested-by: NVictor Kamensky <victor.kamensky@linaro.org>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

Add support for read-only MMIO passthrough mappings by adding a
'writable' parameter to kvm_phys_addr_ioremap. For the moment,
mappings will be read-write even if 'writable' is false, but once
the definition of PAGE_S2_DEVICE gets changed, those mappings will
be created read-only.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

The sgi values calculated in read_set_clear_sgi_pend_reg() and
write_set_clear_sgi_pend_reg() were horribly incorrectly multiplied by 4
with catastrophic results in that subfunctions ended up overwriting
memory not allocated for the expected purpose.

This showed up as bugs in kfree() and the kernel complaining a lot of
you turn on memory debugging.

This addresses: http://marc.info/?l=kvm&m=141164910007868&w=2Reported-by: NShannon Zhao <zhaoshenglong@huawei.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

In order to make the number of interrupts configurable, use the new
fancy device management API to add KVM_DEV_ARM_VGIC_GRP_NR_IRQS as
a VGIC configurable attribute.

Userspace can now specify the exact size of the GIC (by increments
of 32 interrupts).
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

It is now quite easy to delay the allocation of the vgic tables
until we actually require it to be up and running (when the first
vcpu is kicking around, or someones tries to access the GIC registers).

This allow us to allocate memory for the exact number of CPUs we
have. As nobody configures the number of interrupts just yet,
use a fallback to VGIC_NR_IRQS_LEGACY.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>