VGIC implementation.
- s390: support for trapping software breakpoints, nested virtualization
(vSIE), the STHYI opcode, initial extensions for CPU model support.
- MIPS: support for MIPS64 hosts (32-bit guests only) and lots of cleanups,
preliminary to this and the upcoming support for hardware virtualization
extensions.
- x86: support for execute-only mappings in nested EPT; reduced vmexit
latency for TSC deadline timer (by about 30%) on Intel hosts; support for
more than 255 vCPUs.
- PPC: bugfixes.
The ugly bit is the conflicts. A couple of them are simple conflicts due
to 4.7 fixes, but most of them are with other trees. There was definitely
too much reliance on Acked-by here. Some conflicts are for KVM patches
where _I_ gave my Acked-by, but the worst are for this pull request's
patches that touch files outside arch/*/kvm. KVM submaintainers should
probably learn to synchronize better with arch maintainers, with the
latter providing topic branches whenever possible instead of Acked-by.
This is what we do with arch/x86. And I should learn to refuse pull
requests when linux-next sends scary signals, even if that means that
submaintainers have to rebase their branches.
Anyhow, here's the list:
- arch/x86/kvm/vmx.c: handle_pcommit and EXIT_REASON_PCOMMIT was removed
by the nvdimm tree. This tree adds handle_preemption_timer and
EXIT_REASON_PREEMPTION_TIMER at the same place. In general all mentions
of pcommit have to go.
There is also a conflict between a stable fix and this patch, where the
stable fix removed the vmx_create_pml_buffer function and its call.
- virt/kvm/kvm_main.c: kvm_cpu_notifier was removed by the hotplug tree.
This tree adds kvm_io_bus_get_dev at the same place.
- virt/kvm/arm/vgic.c: a few final bugfixes went into 4.7 before the
file was completely removed for 4.8.
- include/linux/irqchip/arm-gic-v3.h: this one is entirely our fault;
this is a change that should have gone in through the irqchip tree and
pulled by kvm-arm. I think I would have rejected this kvm-arm pull
request. The KVM version is the right one, except that it lacks
GITS_BASER_PAGES_SHIFT.
- arch/powerpc: what a mess. For the idle_book3s.S conflict, the KVM
tree is the right one; everything else is trivial. In this case I am
not quite sure what went wrong. The commit that is causing the mess
(fd7bacbca4, "KVM: PPC: Book3S HV: Fix TB corruption in guest exit
path on HMI interrupt", 2016-05-15) touches both arch/powerpc/kernel/
and arch/powerpc/kvm/. It's large, but at 396 insertions/5 deletions
I guessed that it wasn't really possible to split it and that the 5
deletions wouldn't conflict. That wasn't the case.
- arch/s390: also messy. First is hypfs_diag.c where the KVM tree
moved some code and the s390 tree patched it. You have to reapply the
relevant part of commits 6c22c98637, plus all of e030c1125e, to
arch/s390/kernel/diag.c. Or pick the linux-next conflict
resolution from http://marc.info/?l=kvm&m=146717549531603&w=2.
Second, there is a conflict in gmap.c between a stable fix and 4.8.
The KVM version here is the correct one.
I have pushed my resolution at refs/heads/merge-20160802 (commit
3d1f53419842) at git://git.kernel.org/pub/scm/virt/kvm/kvm.git.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
- ARM: GICv3 ITS emulation and various fixes. Removal of the
old VGIC implementation.
- s390: support for trapping software breakpoints, nested
virtualization (vSIE), the STHYI opcode, initial extensions
for CPU model support.
- MIPS: support for MIPS64 hosts (32-bit guests only) and lots
of cleanups, preliminary to this and the upcoming support for
hardware virtualization extensions.
- x86: support for execute-only mappings in nested EPT; reduced
vmexit latency for TSC deadline timer (by about 30%) on Intel
hosts; support for more than 255 vCPUs.
- PPC: bugfixes.
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (302 commits)
KVM: PPC: Introduce KVM_CAP_PPC_HTM
MIPS: Select HAVE_KVM for MIPS64_R{2,6}
MIPS: KVM: Reset CP0_PageMask during host TLB flush
MIPS: KVM: Fix ptr->int cast via KVM_GUEST_KSEGX()
MIPS: KVM: Sign extend MFC0/RDHWR results
MIPS: KVM: Fix 64-bit big endian dynamic translation
MIPS: KVM: Fail if ebase doesn't fit in CP0_EBase
MIPS: KVM: Use 64-bit CP0_EBase when appropriate
MIPS: KVM: Set CP0_Status.KX on MIPS64
MIPS: KVM: Make entry code MIPS64 friendly
MIPS: KVM: Use kmap instead of CKSEG0ADDR()
MIPS: KVM: Use virt_to_phys() to get commpage PFN
MIPS: Fix definition of KSEGX() for 64-bit
KVM: VMX: Add VMCS to CPU's loaded VMCSs before VMPTRLD
kvm: x86: nVMX: maintain internal copy of current VMCS
KVM: PPC: Book3S HV: Save/restore TM state in H_CEDE
KVM: PPC: Book3S HV: Pull out TM state save/restore into separate procedures
KVM: arm64: vgic-its: Simplify MAPI error handling
KVM: arm64: vgic-its: Make vgic_its_cmd_handle_mapi similar to other handlers
KVM: arm64: vgic-its: Turn device_id validation into generic ID validation
...
Pull smp hotplug updates from Thomas Gleixner:
"This is the next part of the hotplug rework.
- Convert all notifiers with a priority assigned
- Convert all CPU_STARTING/DYING notifiers
The final removal of the STARTING/DYING infrastructure will happen
when the merge window closes.
Another 700 hundred line of unpenetrable maze gone :)"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
timers/core: Correct callback order during CPU hot plug
leds/trigger/cpu: Move from CPU_STARTING to ONLINE level
powerpc/numa: Convert to hotplug state machine
arm/perf: Fix hotplug state machine conversion
irqchip/armada: Avoid unused function warnings
ARC/time: Convert to hotplug state machine
clocksource/atlas7: Convert to hotplug state machine
clocksource/armada-370-xp: Convert to hotplug state machine
clocksource/exynos_mct: Convert to hotplug state machine
clocksource/arm_global_timer: Convert to hotplug state machine
rcu: Convert rcutree to hotplug state machine
KVM/arm/arm64/vgic-new: Convert to hotplug state machine
smp/cfd: Convert core to hotplug state machine
x86/x2apic: Convert to CPU hotplug state machine
profile: Convert to hotplug state machine
timers/core: Convert to hotplug state machine
hrtimer: Convert to hotplug state machine
x86/tboot: Convert to hotplug state machine
arm64/armv8 deprecated: Convert to hotplug state machine
hwtracing/coresight-etm4x: Convert to hotplug state machine
...
- GICv3 ITS emulation
- Simpler idmap management that fixes potential TLB conflicts
- Honor the kernel protection in HYP mode
- Removal of the old vgic implementation
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Merge tag 'kvm-arm-for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into next
KVM/ARM changes for Linux 4.8
- GICv3 ITS emulation
- Simpler idmap management that fixes potential TLB conflicts
- Honor the kernel protection in HYP mode
- Removal of the old vgic implementation
The kvm_io_bus framework is a nice place of holding information about
various MMIO regions for kernel emulated devices.
Add a call to retrieve the kvm_io_device structure which is associated
with a certain MMIO address. This avoids to duplicate kvm_io_bus'
knowledge of MMIO regions without having to fake MMIO calls if a user
needs the device a certain MMIO address belongs to.
This will be used by the ITS emulation to get the associated ITS device
when someone triggers an MSI via an ioctl from userspace.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Install the callbacks via the state machine. The core won't invoke the
callbacks on already online CPUs.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.886159080@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Once anon_inode_getfd() has succeeded, it's impossible to undo
in a clean way and no, sys_close() is not usable in such cases.
Use anon_inode_getfile() and get_unused_fd_flags() to get struct file
and descriptor and do *not* install the file into the descriptor table
until after the last possible failure exit.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This reverts commit 77ecc085fed1af1000ca719522977b960aa6da52.
Al Viro colorfully says: "You should *NEVER* use sys_close() on failure
exit paths like that. Moreover, this kvm_put_kvm() becomes a double-put,
since closing the damn file will drop that reference to kvm. Please,
revert. anon_inode_getfd() should be used only when there's no possible
failures past its call".
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The failure of create debugfs of VM will return directly without release
the anon file. It will leak memory and file descriptors, even through
be not serious.
Signed-off-by: Liu Shuo <shuo.a.liu@intel.com>
Fixes: 536a6f88c4
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When freeing the nested resources of a vcpu, there is an assumption that
the vcpu's vmcs01 is the current VMCS on the CPU that executes
nested_release_vmcs12(). If this assumption is violated, the vcpu's
vmcs01 may be made active on multiple CPUs at the same time, in
violation of Intel's specification. Moreover, since the vcpu's vmcs01 is
not VMCLEARed on every CPU on which it is active, it can linger in a
CPU's VMCS cache after it has been freed and potentially
repurposed. Subsequent eviction from the CPU's VMCS cache on a capacity
miss can result in memory corruption.
It is not sufficient for vmx_free_vcpu() to call vmx_load_vmcs01(). If
the vcpu in question was last loaded on a different CPU, it must be
migrated to the current CPU before calling vmx_load_vmcs01().
Signed-off-by: Jim Mattson <jmattson@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The vGPU folks would like to trap the first access to a BAR by setting
vm_ops on the VMAs produced by mmap-ing a VFIO device. The fault handler
then can use remap_pfn_range to place some non-reserved pages in the VMA.
This kind of VM_PFNMAP mapping is not handled by KVM, but follow_pfn
and fixup_user_fault together help supporting it. The patch also supports
VM_MIXEDMAP vmas where the pfns are not reserved and thus subject to
reference counting.
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Tested-by: Neo Jia <cjia@nvidia.com>
Reported-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Handle VM_IO like VM_PFNMAP, as is common in the rest of Linux; extract
the formula to convert hva->pfn into a new function, which will soon
gain more capabilities.
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These days, we experienced one guest crash with 8 cores and 3 disks,
with qemu error logs as bellow:
qemu-system-x86_64: /build/qemu-2.0.0/kvm-all.c:984:
kvm_irqchip_commit_routes: Assertion `ret == 0' failed.
And then we found one patch(bdf026317d) in qemu tree, which said
could fix this bug.
Execute the following script will reproduce the BUG quickly:
irq_affinity.sh
========================================================================
vda_irq_num=25
vdb_irq_num=27
while [ 1 ]
do
for irq in {1,2,4,8,10,20,40,80}
do
echo $irq > /proc/irq/$vda_irq_num/smp_affinity
echo $irq > /proc/irq/$vdb_irq_num/smp_affinity
dd if=/dev/vda of=/dev/zero bs=4K count=100 iflag=direct
dd if=/dev/vdb of=/dev/zero bs=4K count=100 iflag=direct
done
done
========================================================================
The following qemu log is added in the qemu code and is displayed when
this bug reproduced:
kvm_irqchip_commit_routes: max gsi: 1008, nr_allocated_irq_routes: 1024,
irq_routes->nr: 1024, gsi_count: 1024.
That's to say when irq_routes->nr == 1024, there are 1024 routing entries,
but in the kernel code when routes->nr >= 1024, will just return -EINVAL;
The nr is the number of the routing entries which is in of
[1 ~ KVM_MAX_IRQ_ROUTES], not the index in [0 ~ KVM_MAX_IRQ_ROUTES - 1].
This patch fix the BUG above.
Cc: stable@vger.kernel.org
Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Signed-off-by: Wei Tang <tangwei@cmss.chinamobile.com>
Signed-off-by: Zhang Zhuoyu <zhangzhuoyu@cmss.chinamobile.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new created_vcpus field makes it possible to avoid the race between
irqchip and VCPU creation in a much nicer way; just check under kvm->lock
whether a VCPU has already been created.
We can then remove KVM_APIC_ARCHITECTURE too, because at this point the
symbol is only governing the default definition of kvm_vcpu_compatible.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The race between creating the irqchip and the first VCPU is
currently fixed by checking the presence of an irqchip before
updating kvm->online_vcpus, and undoing the whole VCPU creation
if someone created the irqchip in the meanwhile.
Instead, introduce a new field in struct kvm that will count VCPUs
under a mutex, without the atomic access and memory ordering that we
need elsewhere to protect the vcpus array. This also plugs the race
and is more easily applicable in all similar circumstances.
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds a kvm debugfs subdirectory for each VM, which is named
after its pid and file descriptor. The directories contain the same
kind of files that are already in the kvm debugfs directory, but the
data exported through them is now VM specific.
This makes the debugfs kvm data a convenient alternative to the
tracepoints which already have per VM data. The debugfs data is easy
to read and low overhead.
CC: Dan Carpenter <dan.carpenter@oracle.com> [includes fixes by Dan Carpenter]
Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
AVIC has a use for kvm_vcpu_wake_up.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
commit 3491caf275 ("KVM: halt_polling: provide a way to qualify
wakeups during poll") added more aggressive shrinking of the
polling interval if the wakeup did not match some criteria. This
still allows to keep polling enabled if the polling time was
smaller that the current max poll time (block_ns <= vcpu->halt_poll_ns).
Performance measurement shows that even more aggressive shrinking
(shrink polling on any invalid wakeup) reduces absolute and relative
(to the workload) CPU usage even further.
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some wakeups should not be considered a sucessful poll. For example on
s390 I/O interrupts are usually floating, which means that _ALL_ CPUs
would be considered runnable - letting all vCPUs poll all the time for
transactional like workload, even if one vCPU would be enough.
This can result in huge CPU usage for large guests.
This patch lets architectures provide a way to qualify wakeups if they
should be considered a good/bad wakeups in regard to polls.
For s390 the implementation will fence of halt polling for anything but
known good, single vCPU events. The s390 implementation for floating
interrupts does a wakeup for one vCPU, but the interrupt will be delivered
by whatever CPU checks first for a pending interrupt. We prefer the
woken up CPU by marking the poll of this CPU as "good" poll.
This code will also mark several other wakeup reasons like IPI or
expired timers as "good". This will of course also mark some events as
not sucessful. As KVM on z runs always as a 2nd level hypervisor,
we prefer to not poll, unless we are really sure, though.
This patch successfully limits the CPU usage for cases like uperf 1byte
transactional ping pong workload or wakeup heavy workload like OLTP
while still providing a proper speedup.
This also introduced a new vcpu stat "halt_poll_no_tuning" that marks
wakeups that are considered not good for polling.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Radim Krčmář <rkrcmar@redhat.com> (for an earlier version)
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
[Rename config symbol. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The KVM_MAX_VCPUS define provides the maximum number of vCPUs per guest, and
also the upper limit for vCPU ids. This is okay for all archs except PowerPC
which can have higher ids, depending on the cpu/core/thread topology. In the
worst case (single threaded guest, host with 8 threads per core), it limits
the maximum number of vCPUS to KVM_MAX_VCPUS / 8.
This patch separates the vCPU numbering from the total number of vCPUs, with
the introduction of KVM_MAX_VCPU_ID, as the maximal valid value for vCPU ids
plus one.
The corresponding KVM_CAP_MAX_VCPU_ID allows userspace to validate vCPU ids
before passing them to KVM_CREATE_VCPU.
This patch only implements KVM_MAX_VCPU_ID with a specific value for PowerPC.
Other archs continue to return KVM_MAX_VCPUS instead.
Suggested-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
smp_load_acquire() is enough here and it's cheaper than smp_mb().
Adding a comment about reusing memory barrier of kvm_make_all_cpus_request()
here to keep order between modifications to the page tables and reading mode.
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Moving the initialization earlier is needed in 4.6 because
kvm_arch_init_vm is now using mmu_lock, causing lockdep to
complain:
[ 284.440294] INFO: trying to register non-static key.
[ 284.445259] the code is fine but needs lockdep annotation.
[ 284.450736] turning off the locking correctness validator.
...
[ 284.528318] [<ffffffff810aecc3>] lock_acquire+0xd3/0x240
[ 284.533733] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.541467] [<ffffffff81715581>] _raw_spin_lock+0x41/0x80
[ 284.546960] [<ffffffffa0305aa0>] ? kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.554707] [<ffffffffa0305aa0>] kvm_page_track_register_notifier+0x20/0x60 [kvm]
[ 284.562281] [<ffffffffa02ece70>] kvm_mmu_init_vm+0x20/0x30 [kvm]
[ 284.568381] [<ffffffffa02dbf7a>] kvm_arch_init_vm+0x1ea/0x200 [kvm]
[ 284.574740] [<ffffffffa02bff3f>] kvm_dev_ioctl+0xbf/0x4d0 [kvm]
However, it also helps fixing a preexisting problem, which is why this
patch is also good for stable kernels: kvm_create_vm was incrementing
current->mm->mm_count but not decrementing it at the out_err label (in
case kvm_init_mmu_notifier failed). The new initialization order makes
it possible to add the required mmdrop without adding a new error label.
Cc: stable@vger.kernel.org
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull x86 protection key support from Ingo Molnar:
"This tree adds support for a new memory protection hardware feature
that is available in upcoming Intel CPUs: 'protection keys' (pkeys).
There's a background article at LWN.net:
https://lwn.net/Articles/643797/
The gist is that protection keys allow the encoding of
user-controllable permission masks in the pte. So instead of having a
fixed protection mask in the pte (which needs a system call to change
and works on a per page basis), the user can map a (handful of)
protection mask variants and can change the masks runtime relatively
cheaply, without having to change every single page in the affected
virtual memory range.
This allows the dynamic switching of the protection bits of large
amounts of virtual memory, via user-space instructions. It also
allows more precise control of MMU permission bits: for example the
executable bit is separate from the read bit (see more about that
below).
This tree adds the MM infrastructure and low level x86 glue needed for
that, plus it adds a high level API to make use of protection keys -
if a user-space application calls:
mmap(..., PROT_EXEC);
or
mprotect(ptr, sz, PROT_EXEC);
(note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice
this special case, and will set a special protection key on this
memory range. It also sets the appropriate bits in the Protection
Keys User Rights (PKRU) register so that the memory becomes unreadable
and unwritable.
So using protection keys the kernel is able to implement 'true'
PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies
PROT_READ as well. Unreadable executable mappings have security
advantages: they cannot be read via information leaks to figure out
ASLR details, nor can they be scanned for ROP gadgets - and they
cannot be used by exploits for data purposes either.
We know about no user-space code that relies on pure PROT_EXEC
mappings today, but binary loaders could start making use of this new
feature to map binaries and libraries in a more secure fashion.
There is other pending pkeys work that offers more high level system
call APIs to manage protection keys - but those are not part of this
pull request.
Right now there's a Kconfig that controls this feature
(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled
(like most x86 CPU feature enablement code that has no runtime
overhead), but it's not user-configurable at the moment. If there's
any serious problem with this then we can make it configurable and/or
flip the default"
* 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
x86/mm/pkeys: Fix mismerge of protection keys CPUID bits
mm/pkeys: Fix siginfo ABI breakage caused by new u64 field
x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA
mm/core, x86/mm/pkeys: Add execute-only protection keys support
x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags
x86/mm/pkeys: Allow kernel to modify user pkey rights register
x86/fpu: Allow setting of XSAVE state
x86/mm: Factor out LDT init from context init
mm/core, x86/mm/pkeys: Add arch_validate_pkey()
mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits()
x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU
x86/mm/pkeys: Add Kconfig prompt to existing config option
x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps
x86/mm/pkeys: Dump PKRU with other kernel registers
mm/core, x86/mm/pkeys: Differentiate instruction fetches
x86/mm/pkeys: Optimize fault handling in access_error()
mm/core: Do not enforce PKEY permissions on remote mm access
um, pkeys: Add UML arch_*_access_permitted() methods
mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys
x86/mm/gup: Simplify get_user_pages() PTE bit handling
...
but lots of architecture-specific changes.
* ARM:
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- various optimizations to the vgic save/restore code.
* PPC:
- enabled KVM-VFIO integration ("VFIO device")
- optimizations to speed up IPIs between vcpus
- in-kernel handling of IOMMU hypercalls
- support for dynamic DMA windows (DDW).
* s390:
- provide the floating point registers via sync regs;
- separated instruction vs. data accesses
- dirty log improvements for huge guests
- bugfixes and documentation improvements.
* x86:
- Hyper-V VMBus hypercall userspace exit
- alternative implementation of lowest-priority interrupts using vector
hashing (for better VT-d posted interrupt support)
- fixed guest debugging with nested virtualizations
- improved interrupt tracking in the in-kernel IOAPIC
- generic infrastructure for tracking writes to guest memory---currently
its only use is to speedup the legacy shadow paging (pre-EPT) case, but
in the future it will be used for virtual GPUs as well
- much cleanup (LAPIC, kvmclock, MMU, PIT), including ubsan fixes.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"One of the largest releases for KVM... Hardly any generic
changes, but lots of architecture-specific updates.
ARM:
- VHE support so that we can run the kernel at EL2 on ARMv8.1 systems
- PMU support for guests
- 32bit world switch rewritten in C
- various optimizations to the vgic save/restore code.
PPC:
- enabled KVM-VFIO integration ("VFIO device")
- optimizations to speed up IPIs between vcpus
- in-kernel handling of IOMMU hypercalls
- support for dynamic DMA windows (DDW).
s390:
- provide the floating point registers via sync regs;
- separated instruction vs. data accesses
- dirty log improvements for huge guests
- bugfixes and documentation improvements.
x86:
- Hyper-V VMBus hypercall userspace exit
- alternative implementation of lowest-priority interrupts using
vector hashing (for better VT-d posted interrupt support)
- fixed guest debugging with nested virtualizations
- improved interrupt tracking in the in-kernel IOAPIC
- generic infrastructure for tracking writes to guest
memory - currently its only use is to speedup the legacy shadow
paging (pre-EPT) case, but in the future it will be used for
virtual GPUs as well
- much cleanup (LAPIC, kvmclock, MMU, PIT), including ubsan fixes"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (217 commits)
KVM: x86: remove eager_fpu field of struct kvm_vcpu_arch
KVM: x86: disable MPX if host did not enable MPX XSAVE features
arm64: KVM: vgic-v3: Only wipe LRs on vcpu exit
arm64: KVM: vgic-v3: Reset LRs at boot time
arm64: KVM: vgic-v3: Do not save an LR known to be empty
arm64: KVM: vgic-v3: Save maintenance interrupt state only if required
arm64: KVM: vgic-v3: Avoid accessing ICH registers
KVM: arm/arm64: vgic-v2: Make GICD_SGIR quicker to hit
KVM: arm/arm64: vgic-v2: Only wipe LRs on vcpu exit
KVM: arm/arm64: vgic-v2: Reset LRs at boot time
KVM: arm/arm64: vgic-v2: Do not save an LR known to be empty
KVM: arm/arm64: vgic-v2: Move GICH_ELRSR saving to its own function
KVM: arm/arm64: vgic-v2: Save maintenance interrupt state only if required
KVM: arm/arm64: vgic-v2: Avoid accessing GICH registers
KVM: s390: allocate only one DMA page per VM
KVM: s390: enable STFLE interpretation only if enabled for the guest
KVM: s390: wake up when the VCPU cpu timer expires
KVM: s390: step the VCPU timer while in enabled wait
KVM: s390: protect VCPU cpu timer with a seqcount
KVM: s390: step VCPU cpu timer during kvm_run ioctl
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle are:
- Make schedstats a runtime tunable (disabled by default) and
optimize it via static keys.
As most distributions enable CONFIG_SCHEDSTATS=y due to its
instrumentation value, this is a nice performance enhancement.
(Mel Gorman)
- Implement 'simple waitqueues' (swait): these are just pure
waitqueues without any of the more complex features of full-blown
waitqueues (callbacks, wake flags, wake keys, etc.). Simple
waitqueues have less memory overhead and are faster.
Use simple waitqueues in the RCU code (in 4 different places) and
for handling KVM vCPU wakeups.
(Peter Zijlstra, Daniel Wagner, Thomas Gleixner, Paul Gortmaker,
Marcelo Tosatti)
- sched/numa enhancements (Rik van Riel)
- NOHZ performance enhancements (Rik van Riel)
- Various sched/deadline enhancements (Steven Rostedt)
- Various fixes (Peter Zijlstra)
- ... and a number of other fixes, cleanups and smaller enhancements"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
sched/cputime: Fix steal_account_process_tick() to always return jiffies
sched/deadline: Remove dl_new from struct sched_dl_entity
Revert "kbuild: Add option to turn incompatible pointer check into error"
sched/deadline: Remove superfluous call to switched_to_dl()
sched/debug: Fix preempt_disable_ip recording for preempt_disable()
sched, time: Switch VIRT_CPU_ACCOUNTING_GEN to jiffy granularity
time, acct: Drop irq save & restore from __acct_update_integrals()
acct, time: Change indentation in __acct_update_integrals()
sched, time: Remove non-power-of-two divides from __acct_update_integrals()
sched/rt: Kick RT bandwidth timer immediately on start up
sched/debug: Add deadline scheduler bandwidth ratio to /proc/sched_debug
sched/debug: Move sched_domain_sysctl to debug.c
sched/debug: Move the /sys/kernel/debug/sched_features file setup into debug.c
sched/rt: Fix PI handling vs. sched_setscheduler()
sched/core: Remove duplicated sched_group_set_shares() prototype
sched/fair: Consolidate nohz CPU load update code
sched/fair: Avoid using decay_load_missed() with a negative value
sched/deadline: Always calculate end of period on sched_yield()
sched/cgroup: Fix cgroup entity load tracking tear-down
rcu: Use simple wait queues where possible in rcutree
...
When growing halt-polling, there is no check that the poll time exceeds
the limit. It's possible for vcpu->halt_poll_ns grow once past
halt_poll_ns, and stay there until a halt which takes longer than
vcpu->halt_poll_ns. For example, booting a Linux guest with
halt_poll_ns=11000:
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 0 (shrink 10000)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 10000 (grow 0)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 20000 (grow 10000)
Signed-off-by: David Matlack <dmatlack@google.com>
Fixes: aca6ff29c4
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For the kvm_is_error_hva, ubsan complains if the uninitialized writable
is passed to __direct_map, even though the value itself is not used
(__direct_map goes to mmu_set_spte->set_spte->set_mmio_spte but never
looks at that argument).
Ensuring that __gfn_to_pfn_memslot initializes *writable is cheap and
avoids this kind of issue.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The problem:
On -rt, an emulated LAPIC timer instances has the following path:
1) hard interrupt
2) ksoftirqd is scheduled
3) ksoftirqd wakes up vcpu thread
4) vcpu thread is scheduled
This extra context switch introduces unnecessary latency in the
LAPIC path for a KVM guest.
The solution:
Allow waking up vcpu thread from hardirq context,
thus avoiding the need for ksoftirqd to be scheduled.
Normal waitqueues make use of spinlocks, which on -RT
are sleepable locks. Therefore, waking up a waitqueue
waiter involves locking a sleeping lock, which
is not allowed from hard interrupt context.
cyclictest command line:
This patch reduces the average latency in my tests from 14us to 11us.
Daniel writes:
Paolo asked for numbers from kvm-unit-tests/tscdeadline_latency
benchmark on mainline. The test was run 1000 times on
tip/sched/core 4.4.0-rc8-01134-g0905f04:
./x86-run x86/tscdeadline_latency.flat -cpu host
with idle=poll.
The test seems not to deliver really stable numbers though most of
them are smaller. Paolo write:
"Anything above ~10000 cycles means that the host went to C1 or
lower---the number means more or less nothing in that case.
The mean shows an improvement indeed."
Before:
min max mean std
count 1000.000000 1000.000000 1000.000000 1000.000000
mean 5162.596000 2019270.084000 5824.491541 20681.645558
std 75.431231 622607.723969 89.575700 6492.272062
min 4466.000000 23928.000000 5537.926500 585.864966
25% 5163.000000 1613252.750000 5790.132275 16683.745433
50% 5175.000000 2281919.000000 5834.654000 23151.990026
75% 5190.000000 2382865.750000 5861.412950 24148.206168
max 5228.000000 4175158.000000 6254.827300 46481.048691
After
min max mean std
count 1000.000000 1000.00000 1000.000000 1000.000000
mean 5143.511000 2076886.10300 5813.312474 21207.357565
std 77.668322 610413.09583 86.541500 6331.915127
min 4427.000000 25103.00000 5529.756600 559.187707
25% 5148.000000 1691272.75000 5784.889825 17473.518244
50% 5160.000000 2308328.50000 5832.025000 23464.837068
75% 5172.000000 2393037.75000 5853.177675 24223.969976
max 5222.000000 3922458.00000 6186.720500 42520.379830
[Patch was originaly based on the swait implementation found in the -rt
tree. Daniel ported it to mainline's version and gathered the
benchmark numbers for tscdeadline_latency test.]
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-rt-users@vger.kernel.org
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1455871601-27484-4-git-send-email-wagi@monom.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Use list_for_each_entry_safe() instead of list_for_each_safe() to
simplify the code.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Right now halt_poll_ns can be change during runtime. The
grow and shrink factors can only be set during module load.
Lets fix several aspects of grow shrink:
- make grow/shrink changeable by root
- make all variables unsigned int
- read the variables once to prevent races
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We will soon modify the vanilla get_user_pages() so it can no
longer be used on mm/tasks other than 'current/current->mm',
which is by far the most common way it is called. For now,
we allow the old-style calls, but warn when they are used.
(implemented in previous patch)
This patch switches all callers of:
get_user_pages()
get_user_pages_unlocked()
get_user_pages_locked()
to stop passing tsk/mm so they will no longer see the warnings.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: jack@suse.cz
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210156.113E9407@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To date, we have implemented two I/O usage models for persistent memory,
PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
userspace). This series adds a third, DAX-GUP, that allows DAX mappings
to be the target of direct-i/o. It allows userspace to coordinate
DMA/RDMA from/to persistent memory.
The implementation leverages the ZONE_DEVICE mm-zone that went into
4.3-rc1 (also discussed at kernel summit) to flag pages that are owned
and dynamically mapped by a device driver. The pmem driver, after
mapping a persistent memory range into the system memmap via
devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus
page-backed pmem-pfns via flags in the new pfn_t type.
The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the
resulting pte(s) inserted into the process page tables with a new
_PAGE_DEVMAP flag. Later, when get_user_pages() is walking ptes it keys
off _PAGE_DEVMAP to pin the device hosting the page range active.
Finally, get_page() and put_page() are modified to take references
against the device driver established page mapping.
Finally, this need for "struct page" for persistent memory requires
memory capacity to store the memmap array. Given the memmap array for a
large pool of persistent may exhaust available DRAM introduce a
mechanism to allocate the memmap from persistent memory. The new
"struct vmem_altmap *" parameter to devm_memremap_pages() enables
arch_add_memory() to use reserved pmem capacity rather than the page
allocator.
This patch (of 18):
The core has developed a need for a "pfn_t" type [1]. Move the existing
pfn_t in KVM to kvm_pfn_t [2].
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002218.html
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the numbers now overlap, it makes sense to enumerate
them in asm/kvm_host.h rather than linux/kvm_host.h. Functions
that refer to architecture-specific requests are also moved
to arch/.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM creates debugfs files to export VM statistics to userland. To be
able to remove them on kvm exit it tracks the files' dentries.
Since their parent directory is also tracked and since each parent
direntry knows its children we can easily remove them by using
debugfs_remove_recursive(kvm_debugfs_dir). Therefore we don't
need the extra tracking in the kvm_stats_debugfs_item anymore.
Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-By: Sascha Silbe <silbe@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Let's reuse the new common function for VPCU lookup by id.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
[split out the new function into a separate patch]
This patch makes kvm_is_visible_gfn return bool due to this particular
function only using either one or zero as its return value.
No functional change.
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Includes a number of fixes for the arch-timer, introducing proper
level-triggered semantics for the arch-timers, a series of patches to
synchronously halt a guest (prerequisite for IRQ forwarding), some tracepoint
improvements, a tweak for the EL2 panic handlers, some more VGIC cleanups
getting rid of redundant state, and finally a stylistic change that gets rid of
some ctags warnings.
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Merge tag 'kvm-arm-for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/ARM Changes for v4.4-rc1
Includes a number of fixes for the arch-timer, introducing proper
level-triggered semantics for the arch-timers, a series of patches to
synchronously halt a guest (prerequisite for IRQ forwarding), some tracepoint
improvements, a tweak for the EL2 panic handlers, some more VGIC cleanups
getting rid of redundant state, and finally a stylistic change that gets rid of
some ctags warnings.
Conflicts:
arch/x86/include/asm/kvm_host.h
Some times it is useful for architecture implementations of KVM to know
when the VCPU thread is about to block or when it comes back from
blocking (arm/arm64 needs to know this to properly implement timers, for
example).
Therefore provide a generic architecture callback function in line with
what we do elsewhere for KVM generic-arch interactions.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This patch updates the Posted-Interrupts Descriptor when vCPU
is blocked.
pre-block:
- Add the vCPU to the blocked per-CPU list
- Set 'NV' to POSTED_INTR_WAKEUP_VECTOR
post-block:
- Remove the vCPU from the per-CPU list
Signed-off-by: Feng Wu <feng.wu@intel.com>
[Concentrate invocation of pre/post-block hooks to vcpu_block. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
All fields of kvm_io_range were initialized or copied explicitly
afterwards. So switch to use kmalloc().
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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>
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>
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>
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>
