This patchset adds guest PMU support for KVM on ARM64. It takes
trap-and-emulate approach. When guest wants to monitor one event, it
will be trapped by KVM and KVM will call perf_event API to create a perf
event and call relevant perf_event APIs to get the count value of event.
Use perf to test this patchset in guest. When using "perf list", it
shows the list of the hardware events and hardware cache events perf
supports. Then use "perf stat -e EVENT" to monitor some event. For
example, use "perf stat -e cycles" to count cpu cycles and
"perf stat -e cache-misses" to count cache misses.
Below are the outputs of "perf stat -r 5 sleep 5" when running in host
and guest.
Host:
Performance counter stats for 'sleep 5' (5 runs):
0.551428 task-clock (msec) # 0.000 CPUs utilized
( +- 0.91% )
1 context-switches # 0.002 M/sec
0 cpu-migrations # 0.000 K/sec
48 page-faults # 0.088 M/sec
( +- 1.05% )
1150265 cycles # 2.086 GHz
( +- 0.92% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
526398 instructions # 0.46 insns per cycle
( +- 0.89% )
<not supported> branches
9485 branch-misses # 17.201 M/sec
( +- 2.35% )
5.000831616 seconds time elapsed
( +- 0.00% )
Guest:
Performance counter stats for 'sleep 5' (5 runs):
0.730868 task-clock (msec) # 0.000 CPUs utilized
( +- 1.13% )
1 context-switches # 0.001 M/sec
0 cpu-migrations # 0.000 K/sec
48 page-faults # 0.065 M/sec
( +- 0.42% )
1642982 cycles # 2.248 GHz
( +- 1.04% )
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
637964 instructions # 0.39 insns per cycle
( +- 0.65% )
<not supported> branches
10377 branch-misses # 14.198 M/sec
( +- 1.09% )
5.001289068 seconds time elapsed
( +- 0.00% )
This patchset can be fetched from [1] and the relevant QEMU version for
test can be fetched from [2].
Thanks,
Shannon
[1] https://git.linaro.org/people/shannon.zhao/linux-mainline.git
KVM_ARM64_PMU_v3
[2] https://git.linaro.org/people/shannon.zhao/qemu.git PMU_v2
Changes since v2->v3:
* Directly use perf raw event type to create perf_event in KVM
* Add a helper vcpu_sysreg_write
* remove unrelated header file
Changes since v1->v2:
* Use switch...case for registers access handler instead of adding
alone handler for each register
* Try to use the sys_regs to store the register value instead of adding
new variables in struct kvm_pmc
* Fix the handle of cp15 regs
* Create a new kvm device vPMU, then userspace could choose whether to
create PMU
* Fix the handle of PMU overflow interrupt
Shannon Zhao (20):
ARM64: Move PMU register related defines to asm/pmu.h
KVM: ARM64: Define PMU data structure for each vcpu
KVM: ARM64: Add offset defines for PMU registers
KVM: ARM64: Add reset and access handlers for PMCR_EL0 register
KVM: ARM64: Add reset and access handlers for PMSELR register
KVM: ARM64: Add reset and access handlers for PMCEID0 and PMCEID1
register
KVM: ARM64: PMU: Add perf event map and introduce perf event creating
function
KVM: ARM64: Add reset and access handlers for PMXEVTYPER register
KVM: ARM64: Add reset and access handlers for PMXEVCNTR register
KVM: ARM64: Add reset and access handlers for PMCCNTR register
KVM: ARM64: Add reset and access handlers for PMCNTENSET and
PMCNTENCLR register
KVM: ARM64: Add reset and access handlers for PMINTENSET and
PMINTENCLR register
KVM: ARM64: Add reset and access handlers for PMOVSSET and PMOVSCLR
register
KVM: ARM64: Add reset and access handlers for PMUSERENR register
KVM: ARM64: Add reset and access handlers for PMSWINC register
KVM: ARM64: Add access handlers for PMEVCNTRn and PMEVTYPERn register
KVM: ARM64: Add PMU overflow interrupt routing
KVM: ARM64: Reset PMU state when resetting vcpu
KVM: ARM64: Free perf event of PMU when destroying vcpu
KVM: ARM64: Add a new kvm ARM PMU device
Documentation/virtual/kvm/devices/arm-pmu.txt | 15 +
arch/arm/kvm/arm.c | 5 +
arch/arm64/include/asm/kvm_asm.h | 59 +++-
arch/arm64/include/asm/kvm_host.h | 2 +
arch/arm64/include/asm/pmu.h | 47 +++
arch/arm64/include/uapi/asm/kvm.h | 3 +
arch/arm64/kernel/perf_event.c | 35 --
arch/arm64/kvm/Kconfig | 8 +
arch/arm64/kvm/Makefile | 1 +
arch/arm64/kvm/reset.c | 3 +
arch/arm64/kvm/sys_regs.c | 488 ++++++++++++++++++++++++--
arch/arm64/kvm/sys_regs.h | 16 +
include/kvm/arm_pmu.h | 65 ++++
include/linux/kvm_host.h | 1 +
include/uapi/linux/kvm.h | 2 +
virt/kvm/arm/pmu.c | 414 ++++++++++++++++++++++
virt/kvm/kvm_main.c | 4 +
17 files changed, 1098 insertions(+), 70 deletions(-)
create mode 100644 Documentation/virtual/kvm/devices/arm-pmu.txt
create mode 100644 include/kvm/arm_pmu.h
create mode 100644 virt/kvm/arm/pmu.c
--
2.1.4
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