linux-stable.git/arch/mips/kernel/cpu-probe.c, branch v4.7.3

MIPS: Fix incomplete separation of XPA CPU feature

2016-05-28T10:35:03+00:00

Commit 12822570a29b ("MIPS: Separate XPA CPU feature into LPA and MVH")
wasn't fully applied, possibly due to a conflict with commit
f270d881fa55 ("MIPS: Detect MIPSr6 Virtual Processor support"). This
left decode_config5() referring to the non-existent MIPS_CPU_XPA, which
breaks the build when XPA is enabled:

arch/mips/kernel/cpu-probe.c In function ‘decode_config5’:
arch/mips/kernel/cpu-probe.c:838:17: error: ‘MIPS_CPU_XPA’ undeclared (first use in this function)
   c->options |= MIPS_CPU_XPA;
                    ^

Apply the missing hunk, dropping the CONFIG_XPA ifdef and setting the
MIPS_CPU_MVH option when Config5.MVH is set.

Fixes: 12822570a29b ("MIPS: Separate XPA CPU feature into LPA and MVH")
Signed-off-by: James Hogan 
Cc: Paul Burton 
Cc: linux-mips@linux-mips.org
Link: https://patchwork.linux-mips.org/patch/13112/
Patchwork: https://patchwork.linux-mips.org/patch/13277/
Signed-off-by: Ralf Baechle

MIPS: Add probing & defs for VZ & guest features

2016-05-13T13:30:25+00:00

Add a few new cpu-features.h definitions for VZ sub-features, namely the
existence of the CP0_GuestCtl0Ext, CP0_GuestCtl1, and CP0_GuestCtl2
registers, and support for GuestID to dialias TLB entries belonging to
different guests.

Also add certain features present in the guest, with the naming scheme
cpu_guest_has_*. These are added separately to the main options bitfield
since they generally parallel similar features in the root context. A
few of these (FPU, MSA, watchpoints, perf counters, CP0_[X]ContextConfig
registers, MAAR registers, and probably others in future) can be
dynamically configured in the guest context, for which the
cpu_guest_has_dyn_* macros are added.

[ralf@linux-mips.org: Resolve merge conflict.]

Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13231/
Signed-off-by: Ralf Baechle

MIPS: Avoid magic numbers probing kscratch_mask

2016-05-13T13:30:25+00:00

The decode_config4() function reads kscratch_mask from
CP0_Config4.KScrExist using a hard coded shift and mask. We already have
a definition for the mask in mipsregs.h, so add a definition for the
shift and make use of them.

Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13227/
Signed-off-by: Ralf Baechle

MIPS: Add perf counter feature

2016-05-13T13:30:25+00:00

Add CPU feature for standard MIPS r2 performance counters, as determined
by the Config1.PC bit. Both perf_events and oprofile probe this bit, so
lets combine the probing and change both to use cpu_has_perf.

This will also be used for VZ support in KVM to know whether performance
counters exist which can be exposed to guests.

[ralf@linux-mips.org: resolve conflict.]

Signed-off-by: James Hogan 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Robert Richter 
Cc: linux-mips@linux-mips.org
Cc: oprofile-list@lists.sf.net
Patchwork: https://patchwork.linux-mips.org/patch/13226/
Signed-off-by: Ralf Baechle

MIPS: Add defs & probing of [X]ContextConfig

2016-05-13T13:30:25+00:00

The CP0_[X]ContextConfig registers are present if CP0_Config3.CTXTC or
CP0_Config3.SM are set, and provide more control over which bits of
CP0_[X]Context are set to the faulting virtual address on a TLB
exception.

KVM/VZ will need to be able to save and restore these registers in the
guest context, so add the relevant definitions and probing of the
ContextConfig feature in the root context first.

[ralf@linux-mips.org: resolve merge conflict.]

Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13225/
Signed-off-by: Ralf Baechle

MIPS: Add defs & probing of BadInstr[P] registers

2016-05-13T13:30:25+00:00

The optional CP0_BadInstr and CP0_BadInstrP registers are written with
the encoding of the instruction that caused a synchronous exception to
occur, and the prior branch instruction if in a delay slot.

These will be useful for instruction emulation in KVM, and especially
for VZ support where reading guest virtual memory is a bit more awkward.

Add CPU option numbers and cpu_has_* definitions to indicate the
presence of each registers, and add code to probe for them using bits in
the CP0_Config3 register.

[ralf@linux-mips.org: resolve merge conflict.]

Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13224/
Signed-off-by: Ralf Baechle

MIPS: Add defs & probing of extended CP0_EBase

2016-05-13T13:30:25+00:00

The CP0_EBase register may optionally have a write gate (WG) bit to
allow the upper bits to be written, i.e. bits 31:30 on MIPS32 since r3
(to allow for an exception base outside of KSeg0/KSeg1 when segmentation
control is in use) and bits 63:30 on MIPS64 (which also implies the
extension of CP0_EBase to 64 bits long).

The presence of this feature will need to be known about for VZ support
in order to correctly save and restore all the bits of the guest
CP0_EBase register, so add CPU feature definition and probing for this
feature.

Probing the WG bit on MIPS64 can be a bit fiddly, since 64-bit COP0
register access instructions were UNDEFINED for 32-bit registers prior
to MIPS r6, and it'd be nice to be able to probe without clobbering the
existing state, so there are 3 potential paths:

- If we do a 32-bit read of CP0_EBase and the WG bit is already set, the
  register must be 64-bit.

- On MIPS r6 we can do a 64-bit read-modify-write to set CP0_EBase.WG,
  since the upper bits will read 0 and be ignored on write if the
  register is 32-bit.

- On pre-r6 cores, we do a 32-bit read-modify-write of CP0_EBase. This
  avoids the potentially UNDEFINED behaviour, but will clobber the upper
  32-bits of CP0_EBase if it isn't a simple sign extension (which also
  requires us to ensure BEV=1 or modifying the exception base would be
  UNDEFINED too). It is hopefully unlikely a bootloader would set up
  CP0_EBase to a 64-bit segment and leave WG=0.

[ralf@linux-mips.org: Resolved merge conflict.]

Signed-off-by: James Hogan 
Tested-by: Matt Redfearn 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13223/
Signed-off-by: Ralf Baechle

MIPS: BMIPS: BMIPS4380 and BMIPS5000 support RIXI

2016-05-13T13:30:25+00:00

Make BMIPS4380 and BMIPS5000 advertise support for RIXI through
cpu_probe_broadcom(). bmips_cpu_setup() needs to be called shortly after that,
during prom_init() in order to enable the proper Broadcom-specific register to
turn on RIXI and the "rotr" instruction.

Signed-off-by: Florian Fainelli 
Cc: john@phrozen.org
Cc: cernekee@gmail.com
Cc: jon.fraser@broadcom.com
Cc: pgynther@google.com
Cc: paul.burton@imgtec.com
Cc: ddaney.cavm@gmail.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12507/
Signed-off-by: Ralf Baechle

MIPS: Move RIXI exception enabling after vendor-specific cpu_probe

2016-05-13T13:30:25+00:00

Some processors may not have the RIXI bit advertised in the Config3 register,
not being a MIPS32R2 or R6 core, yet, they might be supporting it through a
different way, which is overriden during vendor-specific cpu_probe().

Move the RIXI exceptions enabling after the vendor-specific cpu_probe()
function has had a change to run and override the current CPU's options with
MIPS_CPU_RIXI.

Signed-off-by: Florian Fainelli 
Cc: john@phrozen.org
Cc: cernekee@gmail.com
Cc: jon.fraser@broadcom.com
Cc: pgynther@google.com
Cc: paul.burton@imgtec.com
Cc: ddaney.cavm@gmail.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12506/
Signed-off-by: Ralf Baechle

MIPS: Separate XPA CPU feature into LPA and MVH

2016-05-13T12:02:24+00:00

XPA (eXtended Physical Addressing) should be detected as a combination
of two architectural features:
- Large Physical Address (as per Config3.LPA). With XPA this will be set
  on MIPS32r5 cores, but it may also be set for MIPS64r2 cores too.
- MTHC0/MFHC0 instructions (as per Config5.MVH). With XPA this will be
  set, but it may also be set in VZ guest context even when Config3.LPA
  in the guest context has been cleared by the hypervisor.

As such, XPA is only usable if both bits are set. Update CPU features to
separate these two features, with cpu_has_xpa requiring both to be set.

Signed-off-by: James Hogan 
Cc: Paul Burton 
Cc: Maciej W. Rozycki 
Cc: Joshua Kinard 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13112/
Signed-off-by: Paul Burton 
Signed-off-by: Ralf Baechle