powerpc: Max next_tb to prevent from replaying timer interrupt

With lazy interrupt, we always call __check_irq_replaysome with
decrementers_next_tb to check if we need to replay timer interrupt.
So in hotplug case we also need to set decrementers_next_tb as MAX
to make sure __check_irq_replay don't replay timer interrupt
when return as we expect, otherwise we'll trap here infinitely.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 689dfa894c57842a05bf6dc9f97e6bb71ec5f386)
powerpc: Fix a lazy irq related WARING in arch_local_irq_restore()

The pseries CPU hotplug code uses cede_processor without properly
synchronizing the SW and HW interrupt enable state. This fixes
it using the same helpers that were written for the idle code.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>

=======================
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit fb9125680d0e7c23eae7c6000acc91ea26acab9c)
powerpc: Define differences between doorbells on book3e and book3s

There are a few key differences between doorbells on server compared
with embedded that we care about on Linux, namely:

- We have a new msgsndp instruction for directed privileged doorbells.
  msgsnd is used for directed hypervisor doorbells.
- The tag we use in the instruction is the Thread Identification
  Register of the recipient thread (since server doorbells can only
  occur between threads within a single core), and is only 7 bits wide.
- A new message type is introduced for server doorbells (none of the
  existing book3e message types are currently supported on book3s).

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 42d02b81f265b77be39262666c888d50cb488fc5)

Conflicts:
	arch/powerpc/include/asm/ppc-opcode.h
powerpc: Add book3s hypervisor doorbell exception vectors

Directed Hypervisor Doorbell Interrupts come in at 0xe80 (or
0xc000000000004e80 if relocation on exceptions is enabled), so add
exception vectors at these locations.

If doorbell support is not compiled in we handle it as an
unknown_exception.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 655bb3f4e89225354b668dcef53fa39da02fb1d0)
powerpc: Add book3s privileged doorbell exception vectors

Directed Privileged Doorbell Interrupts come in at 0xa00 (or
0xc000000000004a00 if relocation on exception is enabled), so add
exception vectors at these locations.

If doorbell support is not compiled in we handle it as an
unknown_exception.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 1dbdafec5d63a1de6c83c89a3e953575d60fd393)
powerpc: Select either privileged or hypervisor doorbell when sending

On book3s we have two msgsnd instructions with differing privilege
levels. This patch selects the appropriate instruction to use whenever
we send a doorbell interrupt.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 919ca8681f48ce81848c76f0ed66edb1bb99209b)
powerpc: Add code to handle soft-disabled doorbells on server

This patch adds the logic to properly handle doorbells that come in when
interrupts have been soft disabled and to replay them when interrupts
are re-enabled:

- masked_##_H##interrupt is modified to leave interrupts enabled when a
  doorbell has come in since doorbells are edge sensitive and as such
  won't be automatically re-raised.

- __check_irq_replay now tests if a doorbell happened on book3s, and
  returns either 0xe80 or 0xa00 depending on whether we are the
  hypervisor or not.

- restore_check_irq_replay now tests for the two possible server
  doorbell vector numbers to replay.

- __replay_interrupt also adds tests for the two server doorbell vector
  numbers, and is modified to use a compare instruction rather than an
  andi. on the single bit difference between 0x500 and 0x900.

The last two use a CPU feature section to avoid needlessly testing
against the hypervisor vector if it is not the hypervisor, and vice
versa.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit fe9e1d54e3ea2e5134d7aaa233441f9229326ef6)
powerpc: Update Kconfig + Makefile to prepare for server doorbells

Move the rule to build doorbell support out of the Makefile and into a
new Kconfig boolean that platforms can select.

We will add doorbell support to pseries as well in the next patch.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit 440bc685532fd17c16ec2a3aae2c7877d30b7942)
powerpc: Hook up doorbells on server

This patch actually hooks up doorbell interrupts on POWER8:

- Select the PPC_DOORBELL Kconfig option from PPC_PSERIES

- Add the doorbell CPU feature bit to POWER8

- We define a new pSeries_cause_ipi_mux() function that issues a
  doorbell interrupt if the recipient is another thread within the same
  core as the sender. If the recipient is in a different core it falls
  back to using XICS to deliver the IPI as before.

- During pSeries_smp_probe() at boot, we check if doorbell interrupts
  are supported. If they are we set the cause_ipi function pointer to
  the above mentioned function, otherwise we leave it as whichever XICS
  cause_ipi function was determined by xics_smp_probe().

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(cherry picked from commit e5e84f0a66e0dedba92f881c2dec787dbd8619d5)