We currently do a single update of the vgic state when the distributor
enable/disable control register is accessed and then bypass updating the
state for as long as the distributor remains disabled.
This is incorrect, because updating the state does not consider the
distributor enable bit, and this you can end up in a situation where an
interrupt is marked as pending on the CPU interface, but not pending on
the distributor, which is an impossible state to be in, and triggers a
warning. Consider for example the following sequence of events:
1. An interrupt is marked as pending on the distributor
- the interrupt is also forwarded to the CPU interface
2. The guest turns off the distributor (it's about to do a reboot)
- we stop updating the CPU interface state from now on
3. The guest disables the pending interrupt
- we remove the pending state from the distributor, but don't touch
the CPU interface, see point 2.
Since the distributor disable bit really means that no interrupts should
be forwarded to the CPU interface, we modify the code to keep updating
the internal VGIC state, but always set the CPU interface pending bits
to zero when the distributor is disabled.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
When a guest reboots or offlines/onlines CPUs, it is not uncommon for it
to clear the pending and active states of an interrupt through the
emulated VGIC distributor. However, since the architected timers are
defined by the architecture to be level triggered and the guest
rightfully expects them to be that, but we emulate them as
edge-triggered, we have to mimic level-triggered behavior for an
edge-triggered virtual implementation.
We currently do not signal the VGIC when the map->active field is true,
because it indicates that the guest has already been signalled of the
interrupt as required. Normally this field is set to false when the
guest deactivates the virtual interrupt through the sync path.
We also need to catch the case where the guest deactivates the interrupt
through the emulated distributor, again allowing guests to boot even if
the original virtual timer signal hit before the guest's GIC
initialization sequence is run.
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
We have an interesting issue when the guest disables the timer interrupt
on the VGIC, which happens when turning VCPUs off using PSCI, for
example.
The problem is that because the guest disables the virtual interrupt at
the VGIC level, we never inject interrupts to the guest and therefore
never mark the interrupt as active on the physical distributor. The
host also never takes the timer interrupt (we only use the timer device
to trigger a guest exit and everything else is done in software), so the
interrupt does not become active through normal means.
The result is that we keep entering the guest with a programmed timer
that will always fire as soon as we context switch the hardware timer
state and run the guest, preventing forward progress for the VCPU.
Since the active state on the physical distributor is really part of the
timer logic, it is the job of our virtual arch timer driver to manage
this state.
The timer->map->active boolean field indicates whether we have signalled
this interrupt to the vgic and if that interrupt is still pending or
active. As long as that is the case, the hardware doesn't have to
generate physical interrupts and therefore we mark the interrupt as
active on the physical distributor.
We also have to restore the pending state of an interrupt that was
queued to an LR but was retired from the LR for some reason, while
remaining pending in the LR.
Cc: Marc Zyngier <marc.zyngier@arm.com>
Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
When lowering a level-triggered line from userspace, we forgot to lower
the pending bit on the emulated CPU interface and we also did not
re-compute the pending_on_cpu bitmap for the CPU affected by the change.
Update vgic_update_irq_pending() to fix the two issues above and also
raise a warning in vgic_quue_irq_to_lr if we encounter an interrupt
pending on a CPU which is neither marked active nor pending.
[ Commit text reworked completely - Christoffer ]
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
We observed some performance degradation on s390x with dynamic
halt polling. Until we can provide a proper fix, let's enable
halt_poll_ns as default only for supported architectures.
Architectures are now free to set their own halt_poll_ns
default value.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Second set of KVM/ARM changes for 4.3-rc2
- Workaround for a Cortex-A57 erratum
- Bug fix for the debugging infrastructure
- Fix for 32bit guests with more than 4GB of address space
on a 32bit host
- A number of fixes for the (unusual) case when we don't use
the in-kernel GIC emulation
- Removal of ThumbEE handling on arm64, since these have been
dropped from the architecture before anyone actually ever
built a CPU
- Remove the KVM_ARM_MAX_VCPUS limitation which has become
fairly pointless
This patch removes config option of KVM_ARM_MAX_VCPUS,
and like other ARCHs, just choose the maximum allowed
value from hardware, and follows the reasons:
1) from distribution view, the option has to be
defined as the max allowed value because it need to
meet all kinds of virtulization applications and
need to support most of SoCs;
2) using a bigger value doesn't introduce extra memory
consumption, and the help text in Kconfig isn't accurate
because kvm_vpu structure isn't allocated until request
of creating VCPU is sent from QEMU;
3) the main effect is that the field of vcpus[] in 'struct kvm'
becomes a bit bigger(sizeof(void *) per vcpu) and need more cache
lines to hold the structure, but 'struct kvm' is one generic struct,
and it has worked well on other ARCHs already in this way. Also,
the world switch frequecy is often low, for example, it is ~2000
when running kernel building load in VM from APM xgene KVM host,
so the effect is very small, and the difference can't be observed
in my test at all.
Cc: Dann Frazier <dann.frazier@canonical.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This new statistic can help diagnosing VCPUs that, for any reason,
trigger bad behavior of halt_poll_ns autotuning.
For example, say halt_poll_ns = 480000, and wakeups are spaced exactly
like 479us, 481us, 479us, 481us. Then KVM always fails polling and wastes
10+20+40+80+160+320+480 = 1110 microseconds out of every
479+481+479+481+479+481+479 = 3359 microseconds. The VCPU then
is consuming about 30% more CPU than it would use without
polling. This would show as an abnormally high number of
attempted polling compared to the successful polls.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com<
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, if we had a zero length mmio eventfd assigned on
KVM_MMIO_BUS. It will never be found by kvm_io_bus_cmp() since it
always compares the kvm_io_range() with the length that guest
wrote. This will cause e.g for vhost, kick will be trapped by qemu
userspace instead of vhost. Fixing this by using zero length if an
iodevice is zero length.
Cc: stable@vger.kernel.org
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After 'commit 0b8ba4a2b6 ("KVM: fix checkpatch.pl errors in
kvm/coalesced_mmio.h")', the declaration of the two function will exceed 80
characters.
This patch reduces the TAPs to make each line in 80 characters.
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM/ARM changes for 4.3-rc2
- Fix timer interrupt injection after the rework
that went in during the merge window
- Reset the timer to zero on reboot
- Make sure the TCR_EL2 RES1 bits are really set to 1
- Fix a PSCI affinity bug for non-existing vcpus
If there is already some polling ongoing, it's impossible to disable the
polling, since as soon as somebody sets halt_poll_ns to 0, polling will
never stop, as grow and shrink are only handled if halt_poll_ns is != 0.
This patch fix it by reset vcpu->halt_poll_ns in order to stop polling
when polling is disabled.
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Merge third patch-bomb from Andrew Morton:
- even more of the rest of MM
- lib/ updates
- checkpatch updates
- small changes to a few scruffy filesystems
- kmod fixes/cleanups
- kexec updates
- a dma-mapping cleanup series from hch
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (81 commits)
dma-mapping: consolidate dma_set_mask
dma-mapping: consolidate dma_supported
dma-mapping: cosolidate dma_mapping_error
dma-mapping: consolidate dma_{alloc,free}_noncoherent
dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}
mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd()
mm: make sure all file VMAs have ->vm_ops set
mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
mm: mark most vm_operations_struct const
namei: fix warning while make xmldocs caused by namei.c
ipc: convert invalid scenarios to use WARN_ON
zlib_deflate/deftree: remove bi_reverse()
lib/decompress_unlzma: Do a NULL check for pointer
lib/decompressors: use real out buf size for gunzip with kernel
fs/affs: make root lookup from blkdev logical size
sysctl: fix int -> unsigned long assignments in INT_MIN case
kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo
kexec: align crash_notes allocation to make it be inside one physical page
kexec: remove unnecessary test in kimage_alloc_crash_control_pages()
kexec: split kexec_load syscall from kexec core code
...
In the scope of the idle memory tracking feature, which is introduced by
the following patch, we need to clear the referenced/accessed bit not only
in primary, but also in secondary ptes. The latter is required in order
to estimate wss of KVM VMs. At the same time we want to avoid flushing
tlb, because it is quite expensive and it won't really affect the final
result.
Currently, there is no function for clearing pte young bit that would meet
our requirements, so this patch introduces one. To achieve that we have
to add a new mmu-notifier callback, clear_young, since there is no method
for testing-and-clearing a secondary pte w/o flushing tlb. The new method
is not mandatory and currently only implemented by KVM.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We were taking the exit path after checking ue->flags and return value
of setup_routing_entry(), but 'e' was not freed incase of a failure.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tracepoint for dynamic halt_pool_ns, fired on every potential change.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There is a downside of always-poll since poll is still happened for idle
vCPUs which can waste cpu usage. This patchset add the ability to adjust
halt_poll_ns dynamically, to grow halt_poll_ns when shot halt is detected,
and to shrink halt_poll_ns when long halt is detected.
There are two new kernel parameters for changing the halt_poll_ns:
halt_poll_ns_grow and halt_poll_ns_shrink.
no-poll always-poll dynamic-poll
-----------------------------------------------------------------------
Idle (nohz) vCPU %c0 0.15% 0.3% 0.2%
Idle (250HZ) vCPU %c0 1.1% 4.6%~14% 1.2%
TCP_RR latency 34us 27us 26.7us
"Idle (X) vCPU %c0" is the percent of time the physical cpu spent in
c0 over 60 seconds (each vCPU is pinned to a pCPU). (nohz) means the
guest was tickless. (250HZ) means the guest was ticking at 250HZ.
The big win is with ticking operating systems. Running the linux guest
with nohz=off (and HZ=250), we save 3.4%~12.8% CPUs/second and get close
to no-polling overhead levels by using the dynamic-poll. The savings
should be even higher for higher frequency ticks.
Suggested-by: David Matlack <dmatlack@google.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[Simplify the patch. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Change halt_poll_ns into per-VCPU variable, seeded from module parameter,
to allow greater flexibility.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We currently set the physical active state only when we *inject* a new
pending virtual interrupt, but this is actually not correct, because we
could have been preempted and run something else on the system that
resets the active state to clear. This causes us to run the VM with the
timer set to fire, but without setting the physical active state.
The solution is to always check the LR configurations, and we if have a
mapped interrupt in the LR in either the pending or active state
(virtual), then set the physical active state.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
In order to remove the crude hack where we sneak the masked bit
into the timer's control register, make use of the phys_irq_map
API control the active state of the interrupt.
This causes some limited changes to allow for potential error
propagation.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
