Add base code for supporting the MIPS SIMD Architecture (MSA) in MIPS
KVM guests. MSA cannot yet be enabled in the guest, we're just laying
the groundwork.
As with the FPU, whether the guest's MSA context is loaded is stored in
another bit in the fpu_inuse vcpu member. This allows MSA to be disabled
when the guest disables it, but keeping the MSA context loaded so it
doesn't have to be reloaded if the guest re-enables it.
New assembly code is added for saving and restoring the MSA context,
restoring only the upper half of the MSA context (for if the FPU context
is already loaded) and for saving/clearing and restoring MSACSR (which
can itself cause an MSA FP exception depending on the value). The MSACSR
is restored before returning to the guest if MSA is already enabled, and
the existing FP exception die notifier is extended to catch the possible
MSA FP exception and step over the ctcmsa instruction.
The helper function kvm_own_msa() is added to enable MSA and restore
the MSA context if it isn't already loaded, which will be used in a
later patch when the guest attempts to use MSA for the first time and
triggers an MSA disabled exception.
The existing FPU helpers are extended to handle MSA. kvm_lose_fpu()
saves the full MSA context if it is loaded (which includes the FPU
context) and both kvm_lose_fpu() and kvm_drop_fpu() disable MSA.
kvm_own_fpu() also needs to lose any MSA context if FR=0, since there
would be a risk of getting reserved instruction exceptions if CU1 is
enabled and we later try and save the MSA context. We shouldn't usually
hit this case since it will be handled when emulating CU1 changes,
however there's nothing to stop the guest modifying the Status register
directly via the comm page, which will cause this case to get hit.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add base code for supporting FPU in MIPS KVM guests. The FPU cannot yet
be enabled in the guest, we're just laying the groundwork.
Whether the guest's FPU context is loaded is stored in a bit in the
fpu_inuse vcpu member. This allows the FPU to be disabled when the guest
disables it, but keeping the FPU context loaded so it doesn't have to be
reloaded if the guest re-enables it.
An fpu_enabled vcpu member stores whether userland has enabled the FPU
capability (which will be wired up in a later patch).
New assembly code is added for saving and restoring the FPU context, and
for saving/clearing and restoring FCSR (which can itself cause an FP
exception depending on the value). The FCSR is restored before returning
to the guest if the FPU is already enabled, and a die notifier is
registered to catch the possible FP exception and step over the ctc1
instruction.
The helper function kvm_lose_fpu() is added to save FPU context and
disable the FPU, which is used when saving hardware state before a
context switch or KVM exit (the vcpu_get_regs() callback).
The helper function kvm_own_fpu() is added to enable the FPU and restore
the FPU context if it isn't already loaded, which will be used in a
later patch when the guest attempts to use the FPU for the first time
and triggers a co-processor unusable exception.
The helper function kvm_drop_fpu() is added to discard the FPU context
and disable the FPU, which will be used in a later patch when the FPU
state will become architecturally UNPREDICTABLE (change of FR mode) to
force a reload of [stale] context in the new FR mode.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
When handling floating point exceptions (FPEs) and MSA FPEs the Cause
bits of the appropriate control and status register (FCSR for FPEs and
MSACSR for MSA FPEs) are read and cleared before enabling interrupts,
presumably so that it doesn't have to go through the pain of restoring
those bits if the process is pre-empted, since writing those bits would
cause another immediate exception while still in the kernel.
The bits aren't normally ever restored again, since userland never
expects to see them set.
However for virtualisation it is necessary for the kernel to be able to
restore these Cause bits, as the guest may have been interrupted in an
FP exception handler but before it could read the Cause bits. This can
be done by registering a die notifier, to get notified of the exception
when such a value is restored, and if the PC was at the instruction
which is used to restore the guest state, the handler can step over it
and continue execution. The Cause bits can then remain set without
causing further exceptions.
For this to work safely a few changes are made:
- __build_clear_fpe and __build_clear_msa_fpe no longer clear the Cause
bits, and now return from exception level with interrupts disabled
instead of enabled.
- do_fpe() now clears the Cause bits and enables interrupts after
notify_die() is called, so that the notifier can chose to return from
exception without this happening.
- do_msa_fpe() acts similarly, but now actually makes use of the second
argument (msacsr) and calls notify_die() with the new DIE_MSAFP,
allowing die notifiers to be informed of MSA FPEs too.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
This reverts commit 02987633df.
The basic premise of the patch was incorrect since MSA context
(including FP state) is saved using st.d which stores two consecutive
64-bit words in memory rather than a single 128-bit word. This means
that even with big endian MSA, the FP state is still in the first 64-bit
word.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9168/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
If a ptracee has not used the FPU and the ptracer sets its FP context
using PTRACE_POKEUSR, PTRACE_SETFPREGS or PTRACE_SETREGSET then that
context will be discarded upon either the ptracee using the FPU or a
further write to the context via ptrace. Prevent this loss by recording
that the task has "used" math once its FP context has been written to.
The context initialisation code that was present for the PTRACE_POKEUSR
case is reused for the other 2 cases to provide consistent behaviour
for the different ptrace requests.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9166/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
When running the emulator to handle an instruction that raised an FP
unimplemented operation exception, the FCSR cause bits were being
cleared. This is done to ensure that the kernel does not take an FP
exception when later restoring FP context to registers. However, this
was not being done when the emulator is invoked in response to a
coprocessor unusable exception. This happens in 2 cases:
- There is no FPU present in the system. In this case things were
OK, since the FP context is never restored to hardware registers
and thus no FP exception may be raised when restoring FCSR.
- The FPU could not be configured to the mode required by the task.
In this case it would be possible for the emulator to set cause
bits which are later restored to hardware if the task migrates
to a CPU whose associated FPU does support its mode requirements,
or if the tasks FP mode requirements change.
Consistently clear the cause bits after invoking the emulator, by moving
the clearing to process_fpemu_return and ensuring this is always called
before the tasks FP context is restored. This will make it easier to
catch further paths invoking the emulator in future, as will be
introduced in further patches.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9165/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Much like for traditional scalar FP exceptions, the cause bits in the
MSACSR register need to be cleared following an MSA FP exception.
Without doing so the exception will simply be raised again whenever
the kernel restores MSACSR from a tasks saved context, leading to
undesirable spurious exceptions. Clear the cause bits from the
handle_msa_fpe function, mirroring the way handle_fpe clears the
cause bits in FCSR.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9164/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The {save,restore}_fp_context{,32} functions require that the assembler
allows the use of sdc instructions on any FP register, and this is
acomplished by setting the arch to mips64r2 or mips64r6
(using MIPS_ISA_ARCH_LEVEL_RAW).
However this has the effect of enabling the assembler to use mips64
instructions in the expansion of pseudo-instructions. This was done in
the (now-reverted) commit eec43a224c "MIPS: Save/restore MSA context
around signals" which led to my mistakenly believing that there was an
assembler bug, when in reality the assembler was just emitting mips64
instructions. Avoid the issue for future commits which will add code to
r4k_fpu.S by pushing the .set MIPS_ISA_ARCH_LEVEL_RAW directives into
the functions that require it, and remove the spurious assertion
declaring the assembler bug.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
[james.hogan@imgtec.com: Rebase on v4.0-rc1 and reword commit message to
reflect use of MIPS_ISA_ARCH_LEVEL_RAW]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9612/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Pull MIPS updates from Ralf Baechle:
"This is the main pull request for MIPS:
- a number of fixes that didn't make the 3.19 release.
- a number of cleanups.
- preliminary support for Cavium's Octeon 3 SOCs which feature up to
48 MIPS64 R3 cores with FPU and hardware virtualization.
- support for MIPS R6 processors.
Revision 6 of the MIPS architecture is a major revision of the MIPS
architecture which does away with many of original sins of the
architecture such as branch delay slots. This and other changes in
R6 require major changes throughout the entire MIPS core
architecture code and make up for the lion share of this pull
request.
- finally some preparatory work for eXtendend Physical Address
support, which allows support of up to 40 bit of physical address
space on 32 bit processors"
[ Ahh, MIPS can't leave the PAE brain damage alone. It's like
every CPU architect has to make that mistake, but pee in the snow
by changing the TLA. But whether it's called PAE, LPAE or XPA,
it's horrid crud - Linus ]
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (114 commits)
MIPS: sead3: Corrected get_c0_perfcount_int
MIPS: mm: Remove dead macro definitions
MIPS: OCTEON: irq: add CIB and other fixes
MIPS: OCTEON: Don't do acknowledge operations for level triggered irqs.
MIPS: OCTEON: More OCTEONIII support
MIPS: OCTEON: Remove setting of processor specific CVMCTL icache bits.
MIPS: OCTEON: Core-15169 Workaround and general CVMSEG cleanup.
MIPS: OCTEON: Update octeon-model.h code for new SoCs.
MIPS: OCTEON: Implement DCache errata workaround for all CN6XXX
MIPS: OCTEON: Add little-endian support to asm/octeon/octeon.h
MIPS: OCTEON: Implement the core-16057 workaround
MIPS: OCTEON: Delete unused COP2 saving code
MIPS: OCTEON: Use correct instruction to read 64-bit COP0 register
MIPS: OCTEON: Save and restore CP2 SHA3 state
MIPS: OCTEON: Fix FP context save.
MIPS: OCTEON: Save/Restore wider multiply registers in OCTEON III CPUs
MIPS: boot: Provide more uImage options
MIPS: Remove unneeded #ifdef __KERNEL__ from asm/processor.h
MIPS: ip22-gio: Remove legacy suspend/resume support
mips: pci: Add ifdef around pci_proc_domain
...
The wide multiplier is twice as wide, so we need to save twice as much
state. Detect the multiplier type (CPU type) at start up and install
model specific handlers.
[aleksey.makarov@auriga.com:
conflict resolution,
support for old compilers]
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Leonid Rosenboim <lrosenboim@caviumnetworks.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8933/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Export the _save_msa asm function used by the lose_fpu(1) macro to GPL
modules so that KVM can make use of it when it is built as a module.
This fixes the following build error when CONFIG_KVM=m and
CONFIG_CPU_HAS_MSA=y due to commit f798217dfd ("KVM: MIPS: Don't leak
FPU/DSP to guest"):
ERROR: "_save_msa" [arch/mips/kvm/kvm.ko] undefined!
Fixes: f798217dfd (KVM: MIPS: Don't leak FPU/DSP to guest)
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.15+
Patchwork: https://patchwork.linux-mips.org/patch/9261/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Export the _save_fp asm function used by the lose_fpu(1) macro to GPL
modules so that KVM can make use of it when it is built as a module.
This fixes the following build error when CONFIG_KVM=m due to commit
f798217dfd ("KVM: MIPS: Don't leak FPU/DSP to guest"):
ERROR: "_save_fp" [arch/mips/kvm/kvm.ko] undefined!
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Fixes: f798217dfd (KVM: MIPS: Don't leak FPU/DSP to guest)
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.10+
Patchwork: https://patchwork.linux-mips.org/patch/9260/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The previous implementation did not cover all possible FPU combinations
and it silently allowed ABI incompatible objects to be loaded with the
wrong ABI. For example, the previous logic would set the FP_64 ABI as
the matching ABI for an FP_XX object combined with an FP_64A object.
This was wrong, and the matching ABI should have been FP_64A.
The previous logic is now replaced with a new one which determines
the appropriate FPU mode to be used rather than the FP ABI. This has
the advantage that the entire logic is much simpler since it is the FPU
mode we are interested in rather than the FP ABI resulting to code
simplifications. This also removes the now obsolete FP32XX_HYBRID_FPRS
option.
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
A prctl() call to set FR=0 for MIPS R6 should not be allowed
since FR=1 is the only option for R6 cores.
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The ERETNC instruction, introduced in MIPS R5, is similar to the ERET
one, except it does not clear the LLB bit in the LLADDR register.
This feature is necessary to safely emulate R2 LL/SC instructions.
However, on context switches, we need to clear the LLAddr/LLB bit
in order to make sure that an SC instruction from the new thread
will never succeed if it happens to interrupt an LL operation on the
same address from the previous thread.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 removed quite a few R2 instructions. However, there
is plenty of <R6 userland code so we add an in-kernel emulator
so we can still be able to execute all R2 userland out there.
The emulator comes with a handy debugfs under /mips/ directory
(r2-emul-stats) to provide some basic statistics of the
instructions that are being emulated.
Below are some statistics from booting a minimal buildroot image:
Instruction Total BDslot
------------------------------
movs 236969 0
hilo 56686 0
muls 55279 0
divs 10941 0
dsps 0 0
bops 1 0
traps 0 0
fpus 0 0
loads 214981 17
stores 103364 0
llsc 56898 0
dsemul 150418 0
jr 370158
bltzl 43
bgezl 1594
bltzll 0
bgezll 0
bltzal 39
bgezal 39
beql 14503
bnel 138741
blezl 0
bgtzl 3988
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The LLBIT (bit 4) in the Config5 CP0 register indicates the software
availability of the Load-Linked bit. This bit is only set by hardware
and it has the following meaning:
0: LLB functionality is not supported
1: LLB functionality is supported. The following feature are also
supported:
- ERETNC instruction. Similar to ERET but it does not clear the LLB
bit in the LLAddr register.
- CP0 LLAddr/LLB bit must be set
- LLbit is software accessible through the LLAddr[0]
This will be used later on to emulate R2 LL/SC instructions.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 added the following four instructions which share the
BGTZ and BGTZL opcode:
BLTZALC: Compact branch-and-link if GPR rt is < to zero
BGTZALC: Compact branch-and-link if GPR rt is > to zero
BLTZL : Compact branch if GPR rt is < to zero
BGTZL : Compact branch if GPR rt is > to zero
BLTC : Compact branch if GPR rs is less than GPR rt
BLTUC : Similar to BLTC but unsigned
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 added the following four instructions which share the
BLEZ and BLEZL opcodes:
BLEZALC: Compact branch-and-link if GPR rt is <= to zero
BGEZALC: Compact branch-and-link if GPR rt is >= to zero
BLEZC : Compact branch if GPR rt is <= to zero
BGEZC : Compact branch if GPR rt is >= to zero
BGEC : Compact branch if GPR rs is less than or equal to GPR rt
BGEUC : Similar to BGEC but unsigned.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 introduced the following two branch instructions for COP1:
BC1EQZ: Branch if Cop1 (FPR) Register Bit 0 is Equal to Zero
BC1NEZ: Branch if Cop1 (FPR) Register Bit 0 is Not Equal to Zero
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 removed the BLTZL, BGEZL, BLTZAL, BGEZAL, BEQL, BNEL, BLEZL,
BGTZL branch likely instructions so we must not try to emulate them on
MIPS R6 if the R2-to-R6 emulator is not present.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The MIPS R6 JR instruction is an alias to the JALR one, so it may
need emulation for non-R6 userlands.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6 changed the opcodes for LL/SC instructions so we need to set
the appropriate ISA level.
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The load/store unaligned instructions have been removed in MIPS R6
so we need to re-implement the related macros using the regular
load/store instructions. Moreover, the load/store from coprocessor 2
instructions have been reallocated in Release 6 so we will handle them
in the emulator instead.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The "addi" instruction will trap on overflows which is not something
we need in this code, so we replace that with "addiu".
Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00430.html
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The jr instruction opcode has changed in R6 so make sure
the correct ISA level is set prior using that instruction.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add the MIPS R6 related preprocessor definitions for FPU signal
related functions. MIPS R6 only has FR=1 so avoid checking that
bit on the C0/Status register.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add the MIPS R6 related preprocessor definitions for save/restore
FPU related functions. We also set the appropriate ISA level
so the final return instruction "jr ra" will produce the correct
opcode on R6.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add MIPS R6 support to cache and ftlb exceptions, as well as
to the hwrena and ebase register configuration.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add MIPS R6 support when decoding the config0 c0 register.
Also add MIPS R6 support when examining the ebase c0 register
to get the core number and when getting the shadow set number
from the srsctl c0 register.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Just like MIPS R2, in MIPS R6 it is possible to determine if a
timer interrupt has happened or not.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The current HW bugs checked in cpu-bugs64, do not apply to R6 cores
and they cause compilation problems due to removed <R6 instructions,
so do not check for them for the time being.
Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
MIPS R6, just like MIPS R2, have scratch pad storage, so add a new
symbol which is selected by MIPS R2 and R6.
Link: http://www.linux-mips.org/archives/linux-mips/2015-01/msg00389.html
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
The following instructions have been removed from MIPS R6
ulw, ulh, swl, lwr, lwl, swr.
However, all of them are used in the MIPS specific checksum implementation.
As a result of which, we will use the generic checksum on MIPS R6
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add a case in cpu_probe_mips for the MIPS generic QEMU processor ID.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Add a CPU_QEMU_GENERIC case to various switch statements.
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
James Hogan