1. 21 Jan, 2020 4 commits
    • Miaohe Lin's avatar
      KVM: Fix some wrong function names in comment · 668effb6
      Miaohe Lin authored
      Fix some wrong function names in comment. mmu_check_roots is a typo for
      mmu_check_root, vmcs_read_any should be vmcs12_read_any and so on.
      Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      668effb6
    • Miaohe Lin's avatar
      KVM: x86: check kvm_pit outside kvm_vm_ioctl_reinject() · cad23e72
      Miaohe Lin authored
      check kvm_pit outside kvm_vm_ioctl_reinject() to keep codestyle consistent
      with other kvm_pit func and prepare for futher cleanups.
      Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      cad23e72
    • Wanpeng Li's avatar
      KVM: LAPIC: micro-optimize fixed mode ipi delivery · dfd146fc
      Wanpeng Li authored
      This patch optimizes redundancy logic before fixed mode ipi is delivered
      in the fast path, broadcast handling needs to go slow path, so the delivery
      mode repair can be delayed to before slow path.
      Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      dfd146fc
    • Wanpeng Li's avatar
      KVM: VMX: FIXED+PHYSICAL mode single target IPI fastpath · 1e9e2622
      Wanpeng Li authored
      ICR and TSCDEADLINE MSRs write cause the main MSRs write vmexits in our
      product observation, multicast IPIs are not as common as unicast IPI like
      RESCHEDULE_VECTOR and CALL_FUNCTION_SINGLE_VECTOR etc.
      
      This patch introduce a mechanism to handle certain performance-critical
      WRMSRs in a very early stage of KVM VMExit handler.
      
      This mechanism is specifically used for accelerating writes to x2APIC ICR
      that attempt to send a virtual IPI with physical destination-mode, fixed
      delivery-mode and single target. Which was found as one of the main causes
      of VMExits for Linux workloads.
      
      The reason this mechanism significantly reduce the latency of such virtual
      IPIs is by sending the physical IPI to the target vCPU in a very early stage
      of KVM VMExit handler, before host interrupts are enabled and before expensive
      operations such as reacquiring KVM’s SRCU lock.
      Latency is reduced even more when KVM is able to use APICv posted-interrupt
      mechanism (which allows to deliver the virtual IPI directly to target vCPU
      without the need to kick it to host).
      
      Testing on Xeon Skylake server:
      
      The virtual IPI latency from sender send to receiver receive reduces
      more than 200+ cpu cycles.
      Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Sean Christopherson <sean.j.christopherson@intel.com>
      Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
      Cc: Liran Alon <liran.alon@oracle.com>
      Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1e9e2622
  2. 08 Jan, 2020 36 commits