commit d5361678e63c8a5e72d75cee6d15b840c44306f2
author Wanpeng Li <wanpengli@tencent.com> Thu Mar 26 10:20:02 2020 +0800
committer Paolo Bonzini <pbonzini@redhat.com> Thu Mar 26 05:58:26 2020 -0400
tree f7ff872c969cbe77c3c7e324302781097c0e3d5e
parent 8a1038de11a5536c76054061837b11648bec5b46

KVM: X86: Micro-optimize IPI fastpath delay

This patch optimizes the virtual IPI fastpath emulation sequence:

write ICR2                          send virtual IPI
read ICR2                           write ICR2
send virtual IPI         ==>        write ICR
write ICR

We can observe ~0.67% performance improvement for IPI microbenchmark
(https://lore.kernel.org/kvm/20171219085010.4081-1-ynorov@caviumnetworks.com/)
on Skylake server.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1585189202-1708-4-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>