kernel/linux.git/include/trace/events/kvm.h, branch v4.10.2

KVM: x86: add KVM_CAP_X2APIC_API

2016-07-14T07:03:57+00:00

KVM_CAP_X2APIC_API is a capability for features related to x2APIC enablement. KVM_X2APIC_API_32BIT_FORMAT feature can be enabled to extend APIC ID in get/set ioctl and MSI addresses to 32 bits. Both are needed to support x2APIC. The feature has to be enableable and disabled by default, because get/set ioctl shifted and truncated APIC ID to 8 bits by using a non-standard protocol inspired by xAPIC and the change is not backward-compatible. Changes to MSI addresses follow the format used by interrupt remapping unit. The upper address word, that used to be 0, contains upper 24 bits of the LAPIC address in its upper 24 bits. Lower 8 bits are reserved as 0. Using the upper address word is not backward-compatible either as we didn't check that userspace zeroed the word. Reserved bits are still not explicitly checked, but non-zero data will affect LAPIC addresses, which will cause a bug. Signed-off-by: Radim Krčmář Signed-off-by: Paolo Bonzini

KVM: Unify traced vector format

2016-05-24T10:11:06+00:00

Specifically the change from hex to decimal helps correlating events. Signed-off-by: Jan Kiszka Signed-off-by: Paolo Bonzini

KVM: halt_polling: provide a way to qualify wakeups during poll

2016-05-13T15:29:23+00:00

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 Acked-by: Radim Krčmář (for an earlier version) Cc: David Matlack Cc: Wanpeng Li [Rename config symbol. - Paolo] Signed-off-by: Paolo Bonzini

KVM: halt_polling: improve grow/shrink settings

2016-02-16T17:48:29+00:00

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 Signed-off-by: Paolo Bonzini

kvm: move new trace event outside #ifdef CONFIG_KVM_ASYNC_PF

2015-09-08T09:16:40+00:00

Fixes compilation with ppc64_defconfig. Reported-by: Stephen Rothwell Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini

KVM: trace kvm_halt_poll_ns grow/shrink

2015-09-06T14:33:14+00:00

Tracepoint for dynamic halt_pool_ns, fired on every potential change. Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2015-02-13T17:55:09+00:00

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 ...

kvm: add halt_poll_ns module parameter

2015-02-06T12:08:37+00:00

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

KVM: fix sparse warning in include/trace/events/kvm.h

2015-01-19T10:07:57+00:00

sparse complains about include/trace/events/kvm.h:163:1: error: directive in argument list include/trace/events/kvm.h:167:1: error: directive in argument list include/trace/events/kvm.h:169:1: error: directive in argument list and sparse is right. Preprocessing directives in an argument of a macro are undefined behaviour as of C99 6.10.3p11. Lets use an indirection to fix this. Signed-off-by: Christian Borntraeger Signed-off-by: Paolo Bonzini

kvm/x86/mmu: Pass gfn and level to rmapp callback.

2014-09-24T12:07:57+00:00

Callbacks don't have to do extra computation to learn what the caller (lvm_handle_hva_range()) knows very well. Useful for debugging/tracing/printk/future. Signed-off-by: Andres Lagar-Cavilla Signed-off-by: Paolo Bonzini