linux-stable.git/arch/mips/kernel/cpu-probe.c, branch v5.8

KVM: MIPS: Enable KVM support for Loongson-3

2020-06-04T17:51:53+00:00

This patch enable KVM support for Loongson-3 by selecting HAVE_KVM, but
only enable KVM/VZ on Loongson-3A R4+ (because VZ of early processors
are incomplete). Besides, Loongson-3 support SMP guests, so we clear the
linked load bit of LLAddr in kvm_vz_vcpu_load() if the guest has more
than one VCPUs.

Acked-by: Thomas Bogendoerfer 
Reviewed-by: Aleksandar Markovic 
Signed-off-by: Huacai Chen 
Co-developed-by: Jiaxun Yang 
Message-Id: <1590220602-3547-15-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini

KVM: MIPS: Introduce and use cpu_guest_has_ldpte

2020-06-04T17:49:00+00:00

Loongson-3 has lddir/ldpte instructions and their related CP0 registers
are the same as HTW. So we introduce a cpu_guest_has_ldpte flag and use
it to indicate whether we need to save/restore HTW related CP0 registers
(PWBase, PWSize, PWField and PWCtl).

Acked-by: Thomas Bogendoerfer 
Reviewed-by: Aleksandar Markovic 
Signed-off-by: Huacai Chen 
Co-developed-by: Jiaxun Yang 
Message-Id: <1590220602-3547-7-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini

MIPS: emulate CPUCFG instruction on older Loongson64 cores

2020-05-24T07:26:55+00:00

CPUCFG is the instruction for querying processor characteristics on
newer Loongson processors, much like CPUID of x86. Since the instruction
is supposedly designed to provide a unified way to do feature detection
(without having to, for example, parse /proc/cpuinfo which is too
heavyweight), it is important to provide compatibility for older cores
without native support. Fortunately, most of the fields can be
synthesized without changes to semantics. Performance is not really big
a concern, because feature detection logic is not expected to be
invoked very often in typical userland applications.

The instruction can't be emulated on LOONGSON_2EF cores, according to
FlyGoat's experiments. Because the LWC2 opcode is assigned to other
valid instructions on 2E and 2F, no RI exception is raised for us to
intercept. So compatibility is only extended back furthest to
Loongson-3A1000. Loongson-2K is covered too, as it is basically a remix
of various blocks from the 3A/3B models from a kernel perspective.

This is lightly based on Loongson's work on their Linux 3.10 fork, for
being the authority on the right feature flags to fill in, where things
aren't otherwise discoverable.

Signed-off-by: WANG Xuerui 
Reviewed-by: Jiaxun Yang 
Cc: Huacai Chen 
Cc: Jiaxun Yang 
Cc: Tiezhu Yang 
Signed-off-by: Thomas Bogendoerfer

MIPS: Tidy up CP0.Config6 bits definition

2020-05-24T07:24:49+00:00

CP0.Config6 is a Vendor-defined register whose bits definitions are
different from one to another. Recently, Xuerui's Loongson-3 patch and
Serge's P5600 patch make the definitions inconsistency and unclear.

To make life easy, this patch tidy the definition up:
1, Add a _MTI_ infix for proAptiv/P5600 feature bits;
2, Add a _LOONGSON_ infix for Loongson-3 feature bits;
3, Add bit6/bit7 definition for Loongson-3 which will be used later.

All existing users of these macros are updated.

Cc: WANG Xuerui 
Cc: Serge Semin 
Signed-off-by: Huacai Chen 
Signed-off-by: Thomas Bogendoerfer

mips: Add CP0 Write Merge config support

2020-05-22T07:11:45+00:00

CP0 config register may indicate whether write-through merging
is allowed. Currently there are two types of the merging available:
SysAD Valid and Full modes. Whether each of them are supported by
the core is implementation dependent. Moreover whether the ability
to change the mode also depends on the chip family instance. Taking
into account all of this we created a dedicated mm_config() method
to detect and enable merging if it's supported. It is called for
MIPS-type processors at CPU-probe stage and attempts to detect whether
the write merging is available. If it's known to be supported and
switchable, then switch on the full mode. Otherwise just perform the
CP0.Config.MM field analysis.

In addition there are platforms like InterAptiv/ProAptiv, which do have
the MM bit field set by default, but having write-through cacheing
unsupported makes write-merging also unsupported. In this case we just
ignore the MM field value.

Co-developed-by: Alexey Malahov 
Signed-off-by: Alexey Malahov 
Signed-off-by: Serge Semin 
Cc: Thomas Bogendoerfer 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Arnd Bergmann 
Cc: Rob Herring 
Cc: devicetree@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer

mips: Add MIPS Release 5 support

2020-05-22T07:09:01+00:00

There are five MIPS32/64 architecture releases currently available:
from 1 to 6 except fourth one, which was intentionally skipped.
Three of them can be called as major: 1st, 2nd and 6th, that not only
have some system level alterations, but also introduced significant
core/ISA level updates. The rest of the MIPS architecture releases are
minor.

Even though they don't have as much ISA/system/core level changes
as the major ones with respect to the previous releases, they still
provide a set of updates (I'd say they were intended to be the
intermediate releases before a major one) that might be useful for the
kernel and user-level code, when activated by the kernel or compiler.
In particular the following features were introduced or ended up being
available at/after MIPS32/64 Release 5 architecture:
+ the last release of the misaligned memory access instructions,
+ virtualisation - VZ ASE - is optional component of the arch,
+ SIMD - MSA ASE - is optional component of the arch,
+ DSP ASE is optional component of the arch,
+ CP0.Status.FR=1 for CP1.FIR.F64=1 (pure 64-bit FPU general registers)
  must be available if FPU is implemented,
+ CP1.FIR.Has2008 support is required so CP1.FCSR.{ABS2008,NAN2008} bits
  are available.
+ UFR/UNFR aliases to access CP0.Status.FR from user-space by means of
  ctc1/cfc1 instructions (enabled by CP0.Config5.UFR),
+ CP0.COnfig5.LLB=1 and eretnc instruction are implemented to without
  accidentally clearing LL-bit when returning from an interrupt,
  exception, or error trap,
+ XPA feature together with extended versions of CPx registers is
  introduced, which needs to have mfhc0/mthc0 instructions available.

So due to these changes GNU GCC provides an extended instructions set
support for MIPS32/64 Release 5 by default like eretnc/mfhc0/mthc0. Even
though the architecture alteration isn't that big, it still worth to be
taken into account by the kernel software. Finally we can't deny that
some optimization/limitations might be found in future and implemented
on some level in kernel or compiler. In this case having even
intermediate MIPS architecture releases support would be more than
useful.

So the most of the changes provided by this commit can be split into
either compile- or runtime configs related. The compile-time related
changes are caused by adding the new CONFIG_CPU_MIPS32_R5/CONFIG_CPU_MIPSR5
configs and concern the code activating MIPSR2 or MIPSR6 already
implemented features (like eretnc/LLbit, mthc0/mfhc0). In addition
CPU_HAS_MSA can be now freely enabled for MIPS32/64 release 5 based
platforms as this is done for CPU_MIPS32_R6 CPUs. The runtime changes
concerns the features which are handled with respect to the MIPS ISA
revision detected at run-time by means of CP0.Config.{AT,AR} bits. Alas
these fields can be used to detect either r1 or r2 or r6 releases.
But since we know which CPUs in fact support the R5 arch, we can manually
set MIPS_CPU_ISA_M32R5/MIPS_CPU_ISA_M64R5 bit of c->isa_level and then
use cpu_has_mips32r5/cpu_has_mips64r5 where it's appropriate.

Since XPA/EVA provide too complex alterationss and to have them used with
MIPS32 Release 2 charged kernels (for compatibility with current platform
configs) they are left to be setup as a separate kernel configs.

Co-developed-by: Alexey Malahov 
Signed-off-by: Alexey Malahov 
Signed-off-by: Serge Semin 
Cc: Thomas Bogendoerfer 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Arnd Bergmann 
Cc: Rob Herring 
Cc: devicetree@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer

MIPS: Use fallthrough for arch/mips

2020-05-07T09:55:47+00:00

Convert the various /* fallthrough */ comments to the pseudo-keyword
fallthrough;

Done via script:
https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/

Signed-off-by: Liangliang Huang 
Reviewed-by: Huacai Chen 
Signed-off-by: Thomas Bogendoerfer

MIPS: Loongson64: Correct TLB type for Loongson-3 Classic

2020-05-02T10:05:43+00:00

Huacai just informed me that some early Loongson-3A2000 had wrong
TLB type in Config0 register. That means we have to correct it via
PRID.

It looks like I shoudn't drop MIPS_CPU_FTLB flag in PRID case for
Loongson-3 Classic.

Fixes: da1bd29742b1 ("MIPS: Loongson64: Probe CPU features via CPUCFG")
Signed-off-by: Jiaxun Yang 
Reported-by: Huacai Chen 
Signed-off-by: Thomas Bogendoerfer

MIPS: Loongson64: Probe CPU features via CPUCFG

2020-04-30T14:37:03+00:00

CPUCFG is a Loongson self-defined instruction used to mark CPU
features for Loongson processors started from Loongson-3A4000.

Slightly adjust cpu_probe_loongson function as well. Remove features
that already probed via decode_configs in processor's PRID case
and add a comment about TLBINV.

Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

MIPS: Kernel: Identify Loongson-2K processors

2020-04-26T16:29:01+00:00

Loongson-2K (Loongson64 Reduced) is a family of SoC shipped with
gs264e core.

Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer