On 14/08/2015 12:08, Radim Krčmář wrote: > v3: > * acked by Christian [1/5] > * use ioctl argument directly (unsigned long as flags) [4/5] > * precisely #ifdef arch-specific ioctls [5/5] > v2: > * move request_exits debug counter patch right after introduction of > KVM_REQ_EXIT [3/5] > * use vcpu ioctl instead of vm one [4/5] > * shrink kvm_user_exit from 64 to 32 bytes [4/5] > * new [5/5] > > QEMU uses SIGUSR1 to force a userspace exit and also to queue an early > exit before calling VCPU_RUN -- the signal is blocked in user space and > temporarily unblocked in VCPU_RUN. > The temporal unblocking by sigprocmask() in kvm_arch_vcpu_ioctl_run() > takes a shared siglock, which leads to cacheline bouncing in NUMA > systems. > > This series allows the same with a new request bit and VM IOCTL that > marks and kicks target VCPU, hence no need to unblock. > > inl_from_{pmtimer,qemu} vmexit benchmark from kvm-unit-tests shows ~5% > speedup for 1-4 VCPUs (300-2000 saved cycles) without noticeably > regressing kernel VM exits. > (Paolo did a quick run of older version of this series on a NUMA system > and the speedup was around 35% when utilizing more nodes.) > > Radim Krčmář (5): > KVM: add kvm_has_request wrapper > KVM: add KVM_REQ_EXIT request for userspace exit > KVM: x86: add request_exits debug counter > KVM: add KVM_USER_EXIT vcpu ioctl for userspace exit > KVM: refactor asynchronous vcpu ioctl dispatch > > Documentation/virtual/kvm/api.txt | 25 +++++++++++++++++++++++++ > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/vmx.c | 4 ++-- > arch/x86/kvm/x86.c | 23 +++++++++++++++++++++++ > include/linux/kvm_host.h | 15 +++++++++++++-- > include/uapi/linux/kvm.h | 4 ++++ > virt/kvm/kvm_main.c | 15 ++++++++++----- > 7 files changed, 78 insertions(+), 9 deletions(-) >
Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> ... however, we still need to decide what to do about machine-check exceptions before enabling the capability, otherwise we'd need a new KVM_CAP_USER_EXIT_MCE capability in the future. So I'm holding up the patches for now. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html