Previously the emulation of the CPU timer was just enough to get a Linux
guest running but some shortcuts were taken:
- The guest timer interrupt was hard coded to always happen every 10 ms
rather than being timed to when CP0_Count would match CP0_Compare.
- The guest's CP0_Count register was based on the host's CP0_Count
register. This isn't very portable and fails on cores without a
CP_Count register implemented such as Ingenic XBurst. It also meant
that the guest's CP0_Cause.DC bit to disable the CP0_Count register
took no effect.
- The guest's CP0_Count register was emulated by just dividing the
host's CP0_Count register by 4. This resulted in continuity problems
when used as a clock source, since when the host CP0_Count overflows
from 0x7fffffff to 0x80000000, the guest CP0_Count transitions
discontinuously from 0x1fffffff to 0xe0000000.
Therefore rewrite & fix emulation of the guest timer based on the
monotonic kernel time (i.e. ktime_get()). Internally a 32-bit count_bias
value is added to the frequency scaled nanosecond monotonic time to get
the guest's CP0_Count. The frequency of the timer is initialised to
100MHz and cannot yet be changed, but a later patch will allow the
frequency to be configured via the KVM_{GET,SET}_ONE_REG ioctl
interface.
The timer can now be stopped via the CP0_Cause.DC bit (by the guest or
via the KVM_SET_ONE_REG ioctl interface), at which point the current
CP0_Count is stored and can be read directly. When it is restarted the
bias is recalculated such that the CP0_Count value is continuous.
Due to the nature of hrtimer interrupts any read of the guest's
CP0_Count register while it is running triggers a check for whether the
hrtimer has expired, so that the guest/userland cannot observe the
CP0_Count passing CP0_Compare without queuing a timer interrupt. This is
also taken advantage of when stopping the timer to ensure that a pending
timer interrupt is queued.
This replaces the implementation of:
- Guest read of CP0_Count
- Guest write of CP0_Count
- Guest write of CP0_Compare
- Guest write of CP0_Cause
- Guest read of HWR 2 (CC) with RDHWR
- Host read of CP0_Count via KVM_GET_ONE_REG ioctl interface
- Host write of CP0_Count via KVM_SET_ONE_REG ioctl interface
- Host write of CP0_Compare via KVM_SET_ONE_REG ioctl interface
- Host write of CP0_Cause via KVM_SET_ONE_REG ioctl interface
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The hrtimer callback for guest timer timeouts sets the guest's
CP0_Cause.TI bit to indicate to the guest that a timer interrupt is
pending, however there is no mutual exclusion implemented to prevent
this occurring while the guest's CP0_Cause register is being
read-modify-written elsewhere.
When this occurs the setting of the CP0_Cause.TI bit is undone and the
guest misses the timer interrupt and doesn't reprogram the CP0_Compare
register for the next timeout. Currently another timer interrupt will be
triggered again in another 10ms anyway due to the way timers are
emulated, but after the MIPS timer emulation is fixed this would result
in Linux guest time standing still and the guest scheduler not being
invoked until the guest CP0_Count has looped around again, which at
100MHz takes just under 43 seconds.
Currently this is the only asynchronous modification of guest registers,
therefore it is fixed by adjusting the implementations of the
kvm_set_c0_guest_cause(), kvm_clear_c0_guest_cause(), and
kvm_change_c0_guest_cause() macros which are used for modifying the
guest CP0_Cause register to use ll/sc to ensure atomic modification.
This should work in both UP and SMP cases without requiring interrupts
to be disabled.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Implement KVM_{GET,SET}_ONE_REG ioctl based access to the guest CP0
Count and Compare registers. These registers are special in that writing
to them has side effects (adjusting the time until the next timer
interrupt) and reading of Count depends on the time. Therefore add a
couple of callbacks so that different implementations (trap & emulate or
VZ) can implement them differently depending on what the hardware
provides.
The trap & emulate versions mostly duplicate what happens when a T&E
guest reads or writes these registers, so it inherits the same
limitations which can be fixed in later patches.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: David Daney <david.daney@cavium.com>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MIPS KVM uses mips32_SyncICache to synchronise the icache with the
dcache after dynamically modifying guest instructions or writing guest
exception vector. However this uses rdhwr to get the SYNCI step, which
causes a reserved instruction exception on Ingenic XBurst cores.
It would seem to make more sense to use local_flush_icache_range()
instead which does the same thing but is more portable.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sometimes it's useful to let the user, while doing performance research,
know what in the IEEE754 exceptions has caused many times of FP emulation
when running a specific application. This patch adds 5 more files to
/sys/kernel/debug/mips/fpuemustats/, whose filenames begin with "ieee754".
These stats are in addition to the existing cp1ops, cp1xops, errors, loads
and stores, which may not be useful in understanding the reasons of ieee754
exceptions.
[ralf@linux-mips.org: Fixed reject due to other changes to the kernel
FP assist software.]
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Steven.Hill@imgtec.com
Cc: james.hogan@imgtec.com
Patchwork: http://patchwork.linux-mips.org/patch/7044/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Defines a macro intended to allow trivial use of the regular MIPS wait
instruction from cpuidle drivers, which may simply invoke the macro
within their array of states.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch adds code to generate entry & exit code for various low power
states available on systems based around the MIPS Coherent Processing
System architecture (ie. those with a Coherence Manager, Global
Interrupt Controller & for >=CM2 a Cluster Power Controller). States
supported are:
- Non-coherent wait. This state first leaves the coherent domain and
then executes a regular MIPS wait instruction. Power savings are
found from the elimination of coherency interventions between the
core and any other coherent requestors in the system.
- Clock gated. This state leaves the coherent domain and then gates
the clock input to the core. This removes all dynamic power from the
core but leaves the core at the mercy of another to restart its
clock. Register state is preserved, but the core can not service
interrupts whilst its clock is gated.
- Power gated. This deepest state removes all power input to the core.
All register state is lost and the core will restart execution from
its BEV when another core powers it back up. Because register state
is lost this state requires cooperation with the CONFIG_MIPS_CPS SMP
implementation in order for the core to exit the state successfully.
The code will detect which states are available on the current system
during boot & generate the entry/exit code for those states. This will
be used by cpuidle & hotplug implementations.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
The core power down state for cpuidle will require that the CPS SMP
implementation is in use. This patch provides a mips_cps_smp_in_use
function which determines whether or not the CPS SMP implementation is
currently in use.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
When hotplug and/or a powered down idle state are supported cases will
arise where a non-zero VPE must be brought online without VPE 0, and it
where multiple VPEs must be onlined simultaneously. This patch prepares
for that by:
- Splitting struct boot_config into core & VPE boot config structures,
allocated one per core or VPE respectively. This allows for multiple
VPEs to be onlined simultaneously without clobbering each others
configuration.
- Indicating which VPEs should be online within a core at any given
time using a bitmap. This allows multiple VPEs to be brought online
simultaneously and also indicates to VPE 0 whether it should halt
after starting any non-zero VPEs that should be online within the
core. For example if all VPEs within a core are offlined via hotplug
and the user onlines the second VPE within that core:
1) The core will be powered up.
2) VPE 0 will run from the BEV (ie. mips_cps_core_entry) to
initialise the core.
3) VPE 0 will start VPE 1 because its bit is set in the cores
bitmap.
4) VPE 0 will halt itself because its bit is clear in the cores
bitmap.
- Moving the core & VPE initialisation to assembly code which does not
make any use of the stack. This is because if a non-zero VPE is to
be brought online in a powered down core then when VPE 0 of that
core runs it may not have a valid stack, and even if it did then
it's messy to run through parts of generic kernel code on VPE 0
before starting the correct VPE.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch allows use of the MT ASE yield instruction from uasm. It will
be used by a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch allows for use of the beq instruction with labels from uasm,
much as bne & others already do. It will be used by a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Define a macro to write to the current TCs TCHalt register. This will be
used by a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This is identical to kmap_coherent apart from the cache coherency
attribute used for the TLB entry, so kmap_coherent is abstracted to
kmap_prot which is then called for both kmap_coherent &
kmap_noncoherent. This will be used by a subsequent patch.
Suggested-by: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
pcibios_penalize_isa_irq() is only implemented by x86 now, and legacy ISA
is not used by some architectures. Make pcibios_penalize_isa_irq() a
__weak function to simplify the code. This removes the need for new
platforms to add stub implementations of pcibios_penalize_isa_irq().
[bhelgaas: changelog, comments]
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Nothing was using the method and there isn't any need for this hook. This
leaves smp_cpus_done() empty for the moment.
As suggested by Paul Bolle <pebolle@tiscali.nl>.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Nobody is maintaining SMTC anymore and there also seems to be no userbase.
Which is a pity - the SMTC technology primarily developed by Kevin D.
Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT
ASE's power and elegance.
Based on Markos Chandras <Markos.Chandras@imgtec.com> patch
https://patchwork.linux-mips.org/patch/6719/ which while very similar did
no longer apply cleanly when I tried to merge it plus some additional
post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to
merge once upon a time.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
RM9000 support was removed a while ago but this bit crept back in through
commit 69f24d17 [MIPS: Optimize current_cpu_type() for better code.] which
had been developed before but merged after RM9000 support was removed.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Paul Bolle <pebolle@tiscali.nl>
mm_isBranchInstr() did reside in the math emu code even though it logically
is separate and also is used outside the math emu code. In addition GCC 4.9.0
leaves the following unnnecessarily bloated function body for a non-microMIPS
configuration:
<mm_isBranchInstr>:
105c: afa50004 sw a1,4(sp)
1060: afa60008 sw a2,8(sp)
1064: afa7000c sw a3,12(sp)
1068: 03e00008 jr ra
106c: 00001021 move v0,zero
which stores arguments that are never going to be used on the stack frame.
Move mm_isBranchInstr() from cp1emu.c to branch.c, then split mm_isBranchInstr()
into a __mm_isBranchInstr() core and a mm_isBranchInstr() wrapper inline function
which only invokes __mm_isBranchInstr() on microMIPS configurations.
This shaves off 112 bytes off the kernel and improves code flow a bit.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
asid_cache must be unsigned long otherwise on 64 bit systems it will
become 0 if the value in get_new_mmu_context() reaches 0xffffffff and
in the end the assumption of ASID_FIRST_VERSION is not true anymore
thus leads to more dangerous things.
Initial patch by Yong Zhang <yong.zhang@windriver.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: libin <huawei.libin@huawei.com>
Most of these tests should be runtime tests. This also finally means
that on a MIPS III systems MIPS IV opcodes are going to result in an
exception as they're supposed to.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Commit 231a35d372 [[MIPS] RM: Collected
changes] broke DECstation support by introducing an incompatible copy of
arch/mips/dec/prom/call_o32.S in arch/mips/fw/lib/, built unconditionally.
The copy happens to land earlier of the two among the modules used in the
link and is therefore chosen for the DECstation rather than the intended
original. As a result random kernel data is corrupted because a pointer
to the "%s" formatted output template is used as a temporary stack pointer
rather than being passed down to prom_printf. This also explains why
prom_printf still works, up to a point -- the next argument is the actual
string to output so it works just fine as the output template until enough
kernel data has been corrupted to cause a crash.
This change adjusts the modified wrapper in arch/mips/fw/lib/call_o32.S to
let callers request no stack switching by passing a null temporary stack
pointer in $a1, reworks the DECstation callers to work with the updated
interface and removes the old copy from arch/mips/dec/prom/call_o32.S. A
few minor readability adjustments are included as well, most importantly
O32_SZREG is now used throughout where applicable rather than hardcoded
multiplies of 4 and $fp is used to access the argument save area as a more
usual register to operate the stack with rather than $s0.
Finally an update is made to the temporary stack space used by the SNI
platform to guarantee 8-byte alignment as per o32 requirements.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6668/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This patch provides functions to lock & unlock access to the
"core-other" register region of the CPC. Without performing appropriate
locking it is possible for code using this region to be preempted or to
race with code on another VPE within the same core, with one changing
the core which the "core-other" region is acting upon at an inopportune
time for the other.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch introduces addr_ functions in addition to the existing read_
& write_ functions. The new functions simply return the address of the
appropriate CPC register rather than performing a memory access. This
will be used in a subsequent patch.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Add a mask of CPUs which are currently known to be operating coherently.
This is setup initially to be all present CPUs, but in a subsequent
patch CPUs in a MIPS Coherent Processing System will be cleared in this
mask as they enter non-coherent idle states. This will be used in order
to determine when a CPU within a CPS system may need to be powered back
up, but may also be used in future to optimise away wakeups for cache
operations or TLB invalidations.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
This patch allows the GIC clockevent device for a CPU to be configured
by another CPU. This makes GIC clockevent devices suitable for use as
the tick broadcast device, where formerly the GIC timer local to the
configuring CPU would have been configured incorrectly.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Implement assembler helper macros in asm/pm.h for platform code to use
for saving context across low power states - for example suspend to RAM
or powered down cpuidle states. Macros are provided for saving and
restoring the main CPU context used by C code and doing important
configuration which must be done very early during resume. Notably EVA
needs segmentation control registers to be restored before the stack or
dynamically allocated memory is accessed, so that state is saved in
global data.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Implement a CPU power management callback for restoring trap related CPU
configuration after CPU power up from a low power state. The following
state is restored:
- Status register
- HWREna register
- Exception vector configuration registers
- Context/XContext register
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
The architecture code does not need to access the internals of the FDT
blob directly, so make the pointers to it void * and use char arrays
for section variables.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Tested-by: Grant Likely <grant.likely@linaro.org>
Allow the jz4740 audio drivers to be build when CONFIG_COMPILE_TEST is selected.
This should improve the build test coverage. There is one small piece of
platform dependent code in the jz4740-i2s driver. It uses the DMA request type
constants which are defined in a platform specific header. We can solve this by
moving them from the platform specific header to the I2S driver.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
