This patchset adds pv ipi support for VM. On physical machine, ipi HW uses IOCSR registers, however there is trap into hypervisor when vcpu accesses IOCSR registers if system is in VM mode. SWI is a interrupt mechanism like SGI on ARM, software can send interrupt to CPU, only that on LoongArch SWI can only be sent to local CPU now. So SWI can not used for IPI on real HW system, however it can be used on VM when combined with hypercall method. This patch uses SWI interrupt for IPI mechanism, SWI injection uses hypercall method. And there is one trap with IPI sending, however with SWI interrupt handler there is no trap.
Here is the microbenchmarck data with perf bench futex wake case on 3C5000 single-way machine, there are 16 cpus on 3C5000 single-way machine, VM has 16 vcpus also. The benchmark data is ms time unit to wakeup 16 threads, the performance is higher if data is smaller. perf bench futex wake, Wokeup 16 of 16 threads in ms --physical machine-- --VM original-- --VM with pv ipi patch-- 0.0176 ms 0.1140 ms 0.0481 ms --- Change in V3: 1. Add 128 vcpu ipi multicast support like x86 2. Change cpucfg base address from 0x10000000 to 0x40000000 which is used to dectect hypervisor type, in order to avoid confliction with future hw usage 3. Adjust patch order in this patchset, move patch Refine-ipi-ops-on-LoongArch-platform to the first one. Change in V2: 1. Add hw cpuid map support since ipi routing uses hw cpuid 2. Refine changelog description 3. Add hypercall statistic support for vcpu 4. Set percpu pv ipi message buffer aligned with cacheline 5. Refine pv ipi send logic, do not send ipi message with if there is pending ipi message. --- Bibo Mao (6): LoongArch/smp: Refine ipi ops on LoongArch platform LoongArch: KVM: Add hypercall instruction emulation support LoongArch: KVM: Add cpucfg area for kvm hypervisor LoongArch: Add paravirt interface for guest kernel LoongArch: KVM: Add physical cpuid map support LoongArch: Add pv ipi support on LoongArch system arch/loongarch/Kconfig | 9 + arch/loongarch/include/asm/Kbuild | 1 - arch/loongarch/include/asm/hardirq.h | 5 + arch/loongarch/include/asm/inst.h | 1 + arch/loongarch/include/asm/irq.h | 10 +- arch/loongarch/include/asm/kvm_host.h | 27 +++ arch/loongarch/include/asm/kvm_para.h | 157 ++++++++++++++++++ arch/loongarch/include/asm/kvm_vcpu.h | 1 + arch/loongarch/include/asm/loongarch.h | 11 ++ arch/loongarch/include/asm/paravirt.h | 27 +++ .../include/asm/paravirt_api_clock.h | 1 + arch/loongarch/include/asm/smp.h | 31 ++-- arch/loongarch/include/uapi/asm/Kbuild | 2 - arch/loongarch/kernel/Makefile | 1 + arch/loongarch/kernel/irq.c | 24 +-- arch/loongarch/kernel/paravirt.c | 154 +++++++++++++++++ arch/loongarch/kernel/perf_event.c | 14 +- arch/loongarch/kernel/setup.c | 2 + arch/loongarch/kernel/smp.c | 60 ++++--- arch/loongarch/kernel/time.c | 12 +- arch/loongarch/kvm/exit.c | 125 ++++++++++++-- arch/loongarch/kvm/vcpu.c | 94 ++++++++++- arch/loongarch/kvm/vm.c | 11 ++ 23 files changed, 678 insertions(+), 102 deletions(-) create mode 100644 arch/loongarch/include/asm/kvm_para.h create mode 100644 arch/loongarch/include/asm/paravirt.h create mode 100644 arch/loongarch/include/asm/paravirt_api_clock.h delete mode 100644 arch/loongarch/include/uapi/asm/Kbuild create mode 100644 arch/loongarch/kernel/paravirt.c base-commit: 7a396820222d6d4c02057f41658b162bdcdadd0e -- 2.39.3
