Now that the code is in place for KVM to support MIPS SIMD Architecutre
(MSA) in MIPS guests, wire up the new KVM_CAP_MIPS_MSA capability.
For backwards compatibility, the capability must be explicitly enabled
in order to detect or make use of MSA from the guest.
The capability is not supported if the hardware supports MSA vector
partitioning, since the extra support cannot be tested yet and it
extends the state that the userland program would have to save.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Add KVM register numbers for the MIPS SIMD Architecture (MSA) registers,
and implement access to them with the KVM_GET_ONE_REG / KVM_SET_ONE_REG
ioctls when the MSA capability is enabled (exposed in a later patch) and
present in the guest according to its Config3.MSAP bit.
The MSA vector registers use the same register numbers as the FPU
registers except with a different size (128bits). Since MSA depends on
Status.FR=1, these registers are inaccessible when Status.FR=0. These
registers are returned as a single native endian 128bit value, rather
than least significant half first with each 64-bit half native endian as
the kernel uses internally.
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: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Add guest exception handling for MIPS SIMD Architecture (MSA) floating
point exceptions and MSA disabled exceptions.
MSA floating point exceptions from the guest need passing to the guest
kernel, so for these a guest MSAFPE is emulated.
MSA disabled exceptions are normally handled by passing a reserved
instruction exception to the guest (because no guest MSA was supported),
but the hypervisor can now handle them if the guest has MSA by passing
an MSA disabled exception to the guest, or if the guest has MSA enabled
by transparently restoring the guest MSA context and enabling MSA and
the FPU.
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
Emulate MSA related parts of COP0 interface so that the guest will be
able to enable/disable MSA (Config5.MSAEn) once the MSA capability has
been wired up.
As with the FPU (Status.CU1) setting Config5.MSAEn has no immediate
effect if the MSA state isn't live, as MSA state is restored lazily on
first use. Changes after the MSA state has been restored take immediate
effect, so that the guest can start getting MSA disabled exceptions
right away for guest MSA operations. The MSA state is saved lazily too,
as MSA may get re-enabled in the near future anyway.
A special case is also added for when Status.CU1 is set while FR=0 and
the MSA state is live. In this case we are at risk of getting reserved
instruction exceptions if we try and save the MSA state, so we lose the
MSA state sooner while MSA is still usable.
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 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
Now that the code is in place for KVM to support FPU in MIPS KVM guests,
wire up the new KVM_CAP_MIPS_FPU capability.
For backwards compatibility, the capability must be explicitly enabled
in order to detect or make use of the FPU from the guest.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Add KVM register numbers for the MIPS FPU registers, and implement
access to them with the KVM_GET_ONE_REG / KVM_SET_ONE_REG ioctls when
the FPU capability is enabled (exposed in a later patch) and present in
the guest according to its Config1.FP bit.
The registers are accessible in the current mode of the guest, with each
sized access showing what the guest would see with an equivalent access,
and like the architecture they may become UNPREDICTABLE if the FR mode
is changed. When FR=0, odd doubles are inaccessible as they do not exist
in that mode.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: 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: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Add guest exception handling for floating point exceptions and
coprocessor 1 unusable exceptions.
Floating point exceptions from the guest need passing to the guest
kernel, so for these a guest FPE is emulated.
Also, coprocessor 1 unusable exceptions are normally passed straight
through to the guest (because no guest FPU was supported), but the
hypervisor can now handle them if the guest has its FPU enabled by
restoring the guest FPU context and enabling the FPU.
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
Emulate FPU related parts of COP0 interface so that the guest will be
able to enable/disable the following once the FPU capability has been
wired up:
- The FPU (Status.CU1)
- 64-bit FP register mode (Status.FR)
- Hybrid FP register mode (Config5.FRE)
Changing Status.CU1 has no immediate effect if the FPU state isn't live,
as the FPU state is restored lazily on first use. After that, changes
take place immediately in the host Status.CU1, so that the guest can
start getting coprocessor unusable exceptions right away for guest FPU
operations if it is disabled. The FPU state is saved lazily too, as the
FPU may get re-enabled in the near future anyway.
Any change to Status.FR causes the FPU state to be discarded and FPU
disabled, as the register state is architecturally UNPREDICTABLE after
such a change. This should also ensure that the FPU state is fully
initialised (with stale state, but that's fine) when it is next used in
the new FP mode.
Any change to the Config5.FRE bit is immediately updated in the host
state so that the guest can get the relevant exceptions right away for
single-precision FPU operations.
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
Add a vcpu_get_regs() and vcpu_set_regs() callbacks for loading and
restoring context which may be in hardware registers. This may include
floating point and MIPS SIMD Architecture (MSA) state which may be
accessed directly by the guest (but restored lazily by the hypervisor),
and also dedicated guest registers as provided by the VZ ASE.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add Config4 and Config5 co-processor 0 registers, and add capability to
write the Config1, Config3, Config4, and Config5 registers using the KVM
API.
Only supported bits can be written, to minimise the chances of the guest
being given a configuration from e.g. QEMU that is inconsistent with
that being emulated, and as such the handling is in trap_emul.c as it
may need to be different for VZ. Currently the only modification
permitted is to make Config4 and Config5 exist via the M bits, but other
bits will be added for FPU and MSA support in future patches.
Care should be taken by userland not to change bits without fully
handling the possible extra state that may then exist and which the
guest may begin to use and depend on.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.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
Various semi-used definitions exist in kvm_host.h for the default guest
config registers. Remove them and use the appropriate values directly
when initialising the Config registers.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.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
The information messages when the KVM module is loaded and unloaded are
a bit pointless and out of line with other architectures, so lets drop
them.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.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
Sort the registers in the kvm_mips_get_reg() switch by register number,
which puts ERROREPC after the CONFIG registers.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.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
Implement access to the guest Processor Identification CP0 register
using the KVM_GET_ONE_REG and KVM_SET_ONE_REG ioctls. This allows the
owning process to modify and read back the value that is exposed to the
guest in this register.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.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
Trap instructions are used by Linux to implement BUG_ON(), however KVM
doesn't pass trap exceptions on to the guest if they occur in guest
kernel mode, instead triggering an internal error "Exception Code: 13,
not yet handled". The guest kernel then doesn't get a chance to print
the usual BUG message and stack trace.
Implement handling of the trap exception so that it gets passed to the
guest and the user is left with a more useful log message.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Guest user mode can generate a guest MSA Disabled exception on an MSA
capable core by simply trying to execute an MSA instruction. Since this
exception is unknown to KVM it will be passed on to the guest kernel.
However guest Linux kernels prior to v3.15 do not set up an exception
handler for the MSA Disabled exception as they don't support any MSA
capable cores. This results in a guest OS panic.
Since an older processor ID may be being emulated, and MSA support is
not advertised to the guest, the correct behaviour is to generate a
Reserved Instruction exception in the guest kernel so it can send the
guest process an illegal instruction signal (SIGILL), as would happen
with a non-MSA-capable core.
Fix this as minimally as reasonably possible by preventing
kvm_mips_check_privilege() from relaying MSA Disabled exceptions from
guest user mode to the guest kernel, and handling the MSA Disabled
exception by emulating a Reserved Instruction exception in the guest,
via a new handle_msa_disabled() KVM callback.
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
Cc: <stable@vger.kernel.org> # v3.15+
Enable disabled interrupt, on unsuccessful operation.
Found by Coccinelle.
Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Currently the guest exit trace event saves the VCPU pointer to the
structure, and the guest PC is retrieved by dereferencing it when the
event is printed rather than directly from the trace record. This isn't
safe as the printing may occur long afterwards, after the PC has changed
and potentially after the VCPU has been freed. Usually this results in
the same (wrong) PC being printed for multiple trace events. It also
isn't portable as userland has no way to access the VCPU data structure
when interpreting the trace record itself.
Lets save the actual PC in the structure so that the correct value is
accessible later.
Fixes: 669e846e6c ("KVM/MIPS32: MIPS arch specific APIs for KVM")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org> # v3.10+
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Common: Optional support for adding a small amount of polling on each HLT
instruction executed in the guest (or equivalent for other architectures).
This can improve latency up to 50% on some scenarios (e.g. O_DSYNC writes
or TCP_RR netperf tests). This also has to be enabled manually for now,
but the plan is to auto-tune this in the future.
ARM/ARM64: the highlights are support for GICv3 emulation and dirty page
tracking
s390: several optimizations and bugfixes. Also a first: a feature
exposed by KVM (UUID and long guest name in /proc/sysinfo) before
it is available in IBM's hypervisor! :)
MIPS: Bugfixes.
x86: Support for PML (page modification logging, a new feature in
Broadwell Xeons that speeds up dirty page tracking), nested virtualization
improvements (nested APICv---a nice optimization), usual round of emulation
fixes. There is also a new option to reduce latency of the TSC deadline
timer in the guest; this needs to be tuned manually.
Some commits are common between this pull and Catalin's; I see you
have already included his tree.
ARM has other conflicts where functions are added in the same place
by 3.19-rc and 3.20 patches. These are not large though, and entirely
within KVM.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM update from Paolo Bonzini:
"Fairly small update, but there are some interesting new features.
Common:
Optional support for adding a small amount of polling on each HLT
instruction executed in the guest (or equivalent for other
architectures). This can improve latency up to 50% on some
scenarios (e.g. O_DSYNC writes or TCP_RR netperf tests). This
also has to be enabled manually for now, but the plan is to
auto-tune this in the future.
ARM/ARM64:
The highlights are support for GICv3 emulation and dirty page
tracking
s390:
Several optimizations and bugfixes. Also a first: a feature
exposed by KVM (UUID and long guest name in /proc/sysinfo) before
it is available in IBM's hypervisor! :)
MIPS:
Bugfixes.
x86:
Support for PML (page modification logging, a new feature in
Broadwell Xeons that speeds up dirty page tracking), nested
virtualization improvements (nested APICv---a nice optimization),
usual round of emulation fixes.
There is also a new option to reduce latency of the TSC deadline
timer in the guest; this needs to be tuned manually.
Some commits are common between this pull and Catalin's; I see you
have already included his tree.
Powerpc:
Nothing yet.
The KVM/PPC changes will come in through the PPC maintainers,
because I haven't received them yet and I might end up being
offline for some part of next week"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits)
KVM: ia64: drop kvm.h from installed user headers
KVM: x86: fix build with !CONFIG_SMP
KVM: x86: emulate: correct page fault error code for NoWrite instructions
KVM: Disable compat ioctl for s390
KVM: s390: add cpu model support
KVM: s390: use facilities and cpu_id per KVM
KVM: s390/CPACF: Choose crypto control block format
s390/kernel: Update /proc/sysinfo file with Extended Name and UUID
KVM: s390: reenable LPP facility
KVM: s390: floating irqs: fix user triggerable endless loop
kvm: add halt_poll_ns module parameter
kvm: remove KVM_MMIO_SIZE
KVM: MIPS: Don't leak FPU/DSP to guest
KVM: MIPS: Disable HTW while in guest
KVM: nVMX: Enable nested posted interrupt processing
KVM: nVMX: Enable nested virtual interrupt delivery
KVM: nVMX: Enable nested apic register virtualization
KVM: nVMX: Make nested control MSRs per-cpu
KVM: nVMX: Enable nested virtualize x2apic mode
KVM: nVMX: Prepare for using hardware MSR bitmap
...
This patch introduces a new module parameter for the KVM module; when it
is present, KVM attempts a bit of polling on every HLT before scheduling
itself out via kvm_vcpu_block.
This parameter helps a lot for latency-bound workloads---in particular
I tested it with O_DSYNC writes with a battery-backed disk in the host.
In this case, writes are fast (because the data doesn't have to go all
the way to the platters) but they cannot be merged by either the host or
the guest. KVM's performance here is usually around 30% of bare metal,
or 50% if you use cache=directsync or cache=writethrough (these
parameters avoid that the guest sends pointless flush requests, and
at the same time they are not slow because of the battery-backed cache).
The bad performance happens because on every halt the host CPU decides
to halt itself too. When the interrupt comes, the vCPU thread is then
migrated to a new physical CPU, and in general the latency is horrible
because the vCPU thread has to be scheduled back in.
With this patch performance reaches 60-65% of bare metal and, more
important, 99% of what you get if you use idle=poll in the guest. This
means that the tunable gets rid of this particular bottleneck, and more
work can be done to improve performance in the kernel or QEMU.
Of course there is some price to pay; every time an otherwise idle vCPUs
is interrupted by an interrupt, it will poll unnecessarily and thus
impose a little load on the host. The above results were obtained with
a mostly random value of the parameter (500000), and the load was around
1.5-2.5% CPU usage on one of the host's core for each idle guest vCPU.
The patch also adds a new stat, /sys/kernel/debug/kvm/halt_successful_poll,
that can be used to tune the parameter. It counts how many HLT
instructions received an interrupt during the polling period; each
successful poll avoids that Linux schedules the VCPU thread out and back
in, and may also avoid a likely trip to C1 and back for the physical CPU.
While the VM is idle, a Linux 4 VCPU VM halts around 10 times per second.
Of these halts, almost all are failed polls. During the benchmark,
instead, basically all halts end within the polling period, except a more
or less constant stream of 50 per second coming from vCPUs that are not
running the benchmark. The wasted time is thus very low. Things may
be slightly different for Windows VMs, which have a ~10 ms timer tick.
The effect is also visible on Marcelo's recently-introduced latency
test for the TSC deadline timer. Though of course a non-RT kernel has
awful latency bounds, the latency of the timer is around 8000-10000 clock
cycles compared to 20000-120000 without setting halt_poll_ns. For the TSC
deadline timer, thus, the effect is both a smaller average latency and
a smaller variance.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The FPU and DSP are enabled via the CP0 Status CU1 and MX bits by
kvm_mips_set_c0_status() on a guest exit, presumably in case there is
active state that needs saving if pre-emption occurs. However neither of
these bits are cleared again when returning to the guest.
This effectively gives the guest access to the FPU/DSP hardware after
the first guest exit even though it is not aware of its presence,
allowing FP instructions in guest user code to intermittently actually
execute instead of trapping into the guest OS for emulation. It will
then read & manipulate the hardware FP registers which technically
belong to the user process (e.g. QEMU), or are stale from another user
process. It can also crash the guest OS by causing an FP exception, for
which a guest exception handler won't have been registered.
First lets save and disable the FPU (and MSA) state with lose_fpu(1)
before entering the guest. This simplifies the problem, especially for
when guest FPU/MSA support is added in the future, and prevents FR=1 FPU
state being live when the FR bit gets cleared for the guest, which
according to the architecture causes the contents of the FPU and vector
registers to become UNPREDICTABLE.
We can then safely remove the enabling of the FPU in
kvm_mips_set_c0_status(), since there should never be any active FPU or
MSA state to save at pre-emption, which should plug the FPU leak.
DSP state is always live rather than being lazily restored, so for that
it is simpler to just clear the MX bit again when re-entering the guest.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Sanjay Lal <sanjayl@kymasys.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # v3.10+: 044f0f03eca0: MIPS: KVM: Deliver guest interrupts
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Ensure any hardware page table walker (HTW) is disabled while in KVM
guest mode, as KVM doesn't yet set up hardware page table walking for
guest mappings so the wrong mappings would get loaded, resulting in the
guest hanging or crashing once it reaches userland.
The HTW is disabled and re-enabled around the call to
__kvm_mips_vcpu_run() which does the initial switch into guest mode and
the final switch out of guest context. Additionally it is enabled for
the duration of guest exits (i.e. kvm_mips_handle_exit()), getting
disabled again before returning back to guest or host.
In all cases the HTW is only disabled in normal kernel mode while
interrupts are disabled, so that the HTW doesn't get left disabled if
the process is preempted.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # v3.17+
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The return value of kvm_arch_vcpu_postcreate is not checked in its
caller. This is okay, because only x86 provides vcpu_postcreate right
now and it could only fail if vcpu_load failed. But that is not
possible during KVM_CREATE_VCPU (kvm_arch_vcpu_load is void, too), so
just get rid of the unchecked return value.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
SRCU is not necessary to be compiled by default in all cases. For tinification
efforts not compiling SRCU unless necessary is desirable.
The current patch tries to make compiling SRCU optional by introducing a new
Kconfig option CONFIG_SRCU which is selected when any of the components making
use of SRCU are selected.
If we do not select CONFIG_SRCU, srcu.o will not be compiled at all.
text data bss dec hex filename
2007 0 0 2007 7d7 kernel/rcu/srcu.o
Size of arch/powerpc/boot/zImage changes from
text data bss dec hex filename
831552 64180 23944 919676 e087c arch/powerpc/boot/zImage : before
829504 64180 23952 917636 e0084 arch/powerpc/boot/zImage : after
so the savings are about ~2000 bytes.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: resolve conflict due to removal of arch/ia64/kvm/Kconfig. ]
In the beggining was on_each_cpu(), which required an unused argument to
kvm_arch_ops.hardware_{en,dis}able, but this was soon forgotten.
Remove unnecessary arguments that stem from this.
Signed-off-by: Radim KrÄmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Using static inline is going to save few bytes and cycles.
For example on powerpc, the difference is 700 B after stripping.
(5 kB before)
This patch also deals with two overlooked empty functions:
kvm_arch_flush_shadow was not removed from arch/mips/kvm/mips.c
2df72e9bc KVM: split kvm_arch_flush_shadow
and kvm_arch_sched_in never made it into arch/ia64/kvm/kvm-ia64.c.
e790d9ef6 KVM: add kvm_arch_sched_in
Signed-off-by: Radim KrÄmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce preempt notifiers for architecture specific code.
Advantage over creating a new notifier in every arch is slightly simpler
code and guaranteed call order with respect to kvm_sched_in.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Highlights in this release include:
- BookE: Rework instruction fetch, not racy anymore now
- BookE HV: Fix ONE_REG accessors for some in-hardware registers
- Book3S: Good number of LE host fixes, enable HV on LE
- Book3S: Some misc bug fixes
- Book3S HV: Add in-guest debug support
- Book3S HV: Preload cache lines on context switch
- Remove 440 support
Alexander Graf (31):
KVM: PPC: Book3s PR: Disable AIL mode with OPAL
KVM: PPC: Book3s HV: Fix tlbie compile error
KVM: PPC: Book3S PR: Handle hyp doorbell exits
KVM: PPC: Book3S PR: Fix ABIv2 on LE
KVM: PPC: Book3S PR: Fix sparse endian checks
PPC: Add asm helpers for BE 32bit load/store
KVM: PPC: Book3S HV: Make HTAB code LE host aware
KVM: PPC: Book3S HV: Access guest VPA in BE
KVM: PPC: Book3S HV: Access host lppaca and shadow slb in BE
KVM: PPC: Book3S HV: Access XICS in BE
KVM: PPC: Book3S HV: Fix ABIv2 on LE
KVM: PPC: Book3S HV: Enable for little endian hosts
KVM: PPC: Book3S: Move vcore definition to end of kvm_arch struct
KVM: PPC: Deflect page write faults properly in kvmppc_st
KVM: PPC: Book3S: Stop PTE lookup on write errors
KVM: PPC: Book3S: Add hack for split real mode
KVM: PPC: Book3S: Make magic page properly 4k mappable
KVM: PPC: Remove 440 support
KVM: Rename and add argument to check_extension
KVM: Allow KVM_CHECK_EXTENSION on the vm fd
KVM: PPC: Book3S: Provide different CAPs based on HV or PR mode
KVM: PPC: Implement kvmppc_xlate for all targets
KVM: PPC: Move kvmppc_ld/st to common code
KVM: PPC: Remove kvmppc_bad_hva()
KVM: PPC: Use kvm_read_guest in kvmppc_ld
KVM: PPC: Handle magic page in kvmppc_ld/st
KVM: PPC: Separate loadstore emulation from priv emulation
KVM: PPC: Expose helper functions for data/inst faults
KVM: PPC: Remove DCR handling
KVM: PPC: HV: Remove generic instruction emulation
KVM: PPC: PR: Handle FSCR feature deselects
Alexey Kardashevskiy (1):
KVM: PPC: Book3S: Fix LPCR one_reg interface
Aneesh Kumar K.V (4):
KVM: PPC: BOOK3S: PR: Fix PURR and SPURR emulation
KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
KVM: PPC: BOOK3S: PR: Emulate instruction counter
KVM: PPC: BOOK3S: HV: Update compute_tlbie_rb to handle 16MB base page
Anton Blanchard (2):
KVM: PPC: Book3S HV: Fix ABIv2 indirect branch issue
KVM: PPC: Assembly functions exported to modules need _GLOBAL_TOC()
Bharat Bhushan (10):
kvm: ppc: bookehv: Added wrapper macros for shadow registers
kvm: ppc: booke: Use the shared struct helpers of SRR0 and SRR1
kvm: ppc: booke: Use the shared struct helpers of SPRN_DEAR
kvm: ppc: booke: Add shared struct helpers of SPRN_ESR
kvm: ppc: booke: Use the shared struct helpers for SPRN_SPRG0-7
kvm: ppc: Add SPRN_EPR get helper function
kvm: ppc: bookehv: Save restore SPRN_SPRG9 on guest entry exit
KVM: PPC: Booke-hv: Add one reg interface for SPRG9
KVM: PPC: Remove comment saying SPRG1 is used for vcpu pointer
KVM: PPC: BOOKEHV: rename e500hv_spr to bookehv_spr
Michael Neuling (1):
KVM: PPC: Book3S HV: Add H_SET_MODE hcall handling
Mihai Caraman (8):
KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule
KVM: PPC: e500: Fix default tlb for victim hint
KVM: PPC: e500: Emulate power management control SPR
KVM: PPC: e500mc: Revert "add load inst fixup"
KVM: PPC: Book3e: Add TLBSEL/TSIZE defines for MAS0/1
KVM: PPC: Book3s: Remove kvmppc_read_inst() function
KVM: PPC: Allow kvmppc_get_last_inst() to fail
KVM: PPC: Bookehv: Get vcpu's last instruction for emulation
Paul Mackerras (4):
KVM: PPC: Book3S: Controls for in-kernel sPAPR hypercall handling
KVM: PPC: Book3S: Allow only implemented hcalls to be enabled or disabled
KVM: PPC: Book3S PR: Take SRCU read lock around RTAS kvm_read_guest() call
KVM: PPC: Book3S: Make kvmppc_ld return a more accurate error indication
Stewart Smith (2):
Split out struct kvmppc_vcore creation to separate function
Use the POWER8 Micro Partition Prefetch Engine in KVM HV on POWER8
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Merge tag 'signed-kvm-ppc-next' of git://github.com/agraf/linux-2.6 into kvm
Patch queue for ppc - 2014-08-01
Highlights in this release include:
- BookE: Rework instruction fetch, not racy anymore now
- BookE HV: Fix ONE_REG accessors for some in-hardware registers
- Book3S: Good number of LE host fixes, enable HV on LE
- Book3S: Some misc bug fixes
- Book3S HV: Add in-guest debug support
- Book3S HV: Preload cache lines on context switch
- Remove 440 support
Alexander Graf (31):
KVM: PPC: Book3s PR: Disable AIL mode with OPAL
KVM: PPC: Book3s HV: Fix tlbie compile error
KVM: PPC: Book3S PR: Handle hyp doorbell exits
KVM: PPC: Book3S PR: Fix ABIv2 on LE
KVM: PPC: Book3S PR: Fix sparse endian checks
PPC: Add asm helpers for BE 32bit load/store
KVM: PPC: Book3S HV: Make HTAB code LE host aware
KVM: PPC: Book3S HV: Access guest VPA in BE
KVM: PPC: Book3S HV: Access host lppaca and shadow slb in BE
KVM: PPC: Book3S HV: Access XICS in BE
KVM: PPC: Book3S HV: Fix ABIv2 on LE
KVM: PPC: Book3S HV: Enable for little endian hosts
KVM: PPC: Book3S: Move vcore definition to end of kvm_arch struct
KVM: PPC: Deflect page write faults properly in kvmppc_st
KVM: PPC: Book3S: Stop PTE lookup on write errors
KVM: PPC: Book3S: Add hack for split real mode
KVM: PPC: Book3S: Make magic page properly 4k mappable
KVM: PPC: Remove 440 support
KVM: Rename and add argument to check_extension
KVM: Allow KVM_CHECK_EXTENSION on the vm fd
KVM: PPC: Book3S: Provide different CAPs based on HV or PR mode
KVM: PPC: Implement kvmppc_xlate for all targets
KVM: PPC: Move kvmppc_ld/st to common code
KVM: PPC: Remove kvmppc_bad_hva()
KVM: PPC: Use kvm_read_guest in kvmppc_ld
KVM: PPC: Handle magic page in kvmppc_ld/st
KVM: PPC: Separate loadstore emulation from priv emulation
KVM: PPC: Expose helper functions for data/inst faults
KVM: PPC: Remove DCR handling
KVM: PPC: HV: Remove generic instruction emulation
KVM: PPC: PR: Handle FSCR feature deselects
Alexey Kardashevskiy (1):
KVM: PPC: Book3S: Fix LPCR one_reg interface
Aneesh Kumar K.V (4):
KVM: PPC: BOOK3S: PR: Fix PURR and SPURR emulation
KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
KVM: PPC: BOOK3S: PR: Emulate instruction counter
KVM: PPC: BOOK3S: HV: Update compute_tlbie_rb to handle 16MB base page
Anton Blanchard (2):
KVM: PPC: Book3S HV: Fix ABIv2 indirect branch issue
KVM: PPC: Assembly functions exported to modules need _GLOBAL_TOC()
Bharat Bhushan (10):
kvm: ppc: bookehv: Added wrapper macros for shadow registers
kvm: ppc: booke: Use the shared struct helpers of SRR0 and SRR1
kvm: ppc: booke: Use the shared struct helpers of SPRN_DEAR
kvm: ppc: booke: Add shared struct helpers of SPRN_ESR
kvm: ppc: booke: Use the shared struct helpers for SPRN_SPRG0-7
kvm: ppc: Add SPRN_EPR get helper function
kvm: ppc: bookehv: Save restore SPRN_SPRG9 on guest entry exit
KVM: PPC: Booke-hv: Add one reg interface for SPRG9
KVM: PPC: Remove comment saying SPRG1 is used for vcpu pointer
KVM: PPC: BOOKEHV: rename e500hv_spr to bookehv_spr
Michael Neuling (1):
KVM: PPC: Book3S HV: Add H_SET_MODE hcall handling
Mihai Caraman (8):
KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule
KVM: PPC: e500: Fix default tlb for victim hint
KVM: PPC: e500: Emulate power management control SPR
KVM: PPC: e500mc: Revert "add load inst fixup"
KVM: PPC: Book3e: Add TLBSEL/TSIZE defines for MAS0/1
KVM: PPC: Book3s: Remove kvmppc_read_inst() function
KVM: PPC: Allow kvmppc_get_last_inst() to fail
KVM: PPC: Bookehv: Get vcpu's last instruction for emulation
Paul Mackerras (4):
KVM: PPC: Book3S: Controls for in-kernel sPAPR hypercall handling
KVM: PPC: Book3S: Allow only implemented hcalls to be enabled or disabled
KVM: PPC: Book3S PR: Take SRCU read lock around RTAS kvm_read_guest() call
KVM: PPC: Book3S: Make kvmppc_ld return a more accurate error indication
Stewart Smith (2):
Split out struct kvmppc_vcore creation to separate function
Use the POWER8 Micro Partition Prefetch Engine in KVM HV on POWER8
Conflicts:
Documentation/virtual/kvm/api.txt
few days.
MIPS and s390 have little going on this release; just bugfixes, some
small, some larger.
The highlights for x86 are nested VMX improvements (Jan Kiszka), optimizations
for old processor (up to Nehalem, by me and Bandan Das), and a lot of x86
emulator bugfixes (Nadav Amit).
Stephen Rothwell reported a trivial conflict with the tracing branch.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM changes from Paolo Bonzini:
"These are the x86, MIPS and s390 changes; PPC and ARM will come in a
few days.
MIPS and s390 have little going on this release; just bugfixes, some
small, some larger.
The highlights for x86 are nested VMX improvements (Jan Kiszka),
optimizations for old processor (up to Nehalem, by me and Bandan Das),
and a lot of x86 emulator bugfixes (Nadav Amit).
Stephen Rothwell reported a trivial conflict with the tracing branch"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (104 commits)
x86/kvm: Resolve shadow warnings in macro expansion
KVM: s390: rework broken SIGP STOP interrupt handling
KVM: x86: always exit on EOIs for interrupts listed in the IOAPIC redir table
KVM: vmx: remove duplicate vmx_mpx_supported() prototype
KVM: s390: Fix memory leak on busy SIGP stop
x86/kvm: Resolve shadow warning from min macro
kvm: Resolve missing-field-initializers warnings
Replace NR_VMX_MSR with its definition
KVM: x86: Assertions to check no overrun in MSR lists
KVM: x86: set rflags.rf during fault injection
KVM: x86: Setting rflags.rf during rep-string emulation
KVM: x86: DR6/7.RTM cannot be written
KVM: nVMX: clean up nested_release_vmcs12 and code around it
KVM: nVMX: fix lifetime issues for vmcs02
KVM: x86: Defining missing x86 vectors
KVM: x86: emulator injects #DB when RFLAGS.RF is set
KVM: x86: Cleanup of rflags.rf cleaning
KVM: x86: Clear rflags.rf on emulated instructions
KVM: x86: popf emulation should not change RF
KVM: x86: Clearing rflags.rf upon skipped emulated instruction
...
In preparation to make the check_extension function available to VM scope
we add a struct kvm * argument to the function header and rename the function
accordingly. It will still be called from the /dev/kvm fd, but with a NULL
argument for struct kvm *.
Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
It's impossible to fall into the error handling of the TLB index after
being masked by (KVM_MIPS_GUEST_TLB_SIZE - 1). Remove the dead code.
Reported-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The commpage is allocated using kzalloc(), so there's no need of cleaning
the memory of the kvm_mips_commpage struct and its internal mips_coproc.
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Since all the files are in arch/mips/kvm/, there's no need of the prefixes
"kvm_" and "kvm_mips_".
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The keyword volatile for idx in the TLB functions is unnecessary.
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
kvm_arch_vcpu_free() is called in 2 code paths:
1) kvm_vm_ioctl()
kvm_vm_ioctl_create_vcpu()
kvm_arch_vcpu_destroy()
kvm_arch_vcpu_free()
2) kvm_put_kvm()
kvm_destroy_vm()
kvm_arch_destroy_vm()
kvm_mips_free_vcpus()
kvm_arch_vcpu_free()
Neither of the paths handles VCPU free. We need to do it in
kvm_arch_vcpu_free() corresponding to the memory allocation in
kvm_arch_vcpu_create().
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: stable@vger.kernel.org
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The kfree() function already NULL checks the parameter so remove the
redundant NULL checks before kfree() calls in arch/mips/kvm/.
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 logging from MIPS KVM is fairly noisy with kvm_info() in places
where it shouldn't be, such as on VM creation and migration to a
different CPU. Replace these kvm_info() calls with kvm_debug().
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>
kvm_debug() uses pr_debug() which is already compiled out in the absence
of a DEBUG define, so remove the unnecessary ifdef DEBUG lines around
kvm_debug() calls which are littered around arch/mips/kvm/.
As well as generally cleaning up, this prevents future bit-rot due to
DEBUG not being commonly used.
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>
Fix build errors when DEBUG is defined in arch/mips/kvm/.
- The DEBUG code in kvm_mips_handle_tlbmod() was missing some variables.
- The DEBUG code in kvm_mips_host_tlb_write() was conditional on an
undefined "debug" variable.
- The DEBUG code in kvm_mips_host_tlb_inv() accessed asid_map directly
rather than using kvm_mips_get_user_asid(). Also fixed brace
placement.
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 kvm_mips_comparecount_func() and kvm_mips_comparecount_wakeup()
functions are only used within arch/mips/kvm/kvm_mips.c, so make them
static.
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>
Expose the KVM guest CP0_Count frequency to userland via a new
KVM_REG_MIPS_COUNT_HZ register accessible with the KVM_{GET,SET}_ONE_REG
ioctls.
When the frequency is altered the bias is adjusted such that the guest
CP0_Count doesn't jump discontinuously or lose any timer interrupts.
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>
Expose two new virtual registers to userland via the
KVM_{GET,SET}_ONE_REG ioctls.
KVM_REG_MIPS_COUNT_CTL is for timer configuration fields and just
contains a master disable count bit. This can be used by userland to
freeze the timer in order to read a consistent state from the timer
count value and timer interrupt pending bit. This cannot be done with
the CP0_Cause.DC bit because the timer interrupt pending bit (TI) is
also in CP0_Cause so it would be impossible to stop the timer without
also risking a race with an hrtimer interrupt and having to explicitly
check whether an interrupt should have occurred.
When the timer is re-enabled it resumes without losing time, i.e. the
CP0_Count value jumps to what it would have been had the timer not been
disabled, which would also be impossible to do from userland with
CP0_Cause.DC. The timer interrupt also cannot be lost, i.e. if a timer
interrupt would have occurred had the timer not been disabled it is
queued when the timer is re-enabled.
This works by storing the nanosecond monotonic time when the master
disable is set, and using it for various operations instead of the
current monotonic time (e.g. when recalculating the bias when the
CP0_Count is set), until the master disable is cleared again, i.e. the
timer state is read/written as it would have been at that time. This
state is exposed to userland via the read-only KVM_REG_MIPS_COUNT_RESUME
virtual register so that userland can determine the exact time the
master disable took effect.
This should allow userland to atomically save the state of the timer,
and later restore it.
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>
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>
Nicholas Mc Guire