KVM: VMX: Handle preemption timer fastpath

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This patch implements a fastpath for the preemption timer vmexit.  The vmexit
can be handled quickly so it can be performed with interrupts off and going
back directly to the guest.

Testing on SKX Server.

cyclictest in guest(w/o mwait exposed, adaptive advance lapic timer is default -1):

5540.5ns -> 4602ns       17%

kvm-unit-test/vmexit.flat:

w/o avanced timer:
tscdeadline_immed: 3028.5  -> 2494.75  17.6%
tscdeadline:       5765.7  -> 5285      8.3%

w/ adaptive advance timer default -1:
tscdeadline_immed: 3123.75 -> 2583     17.3%
tscdeadline:       4663.75 -> 4537      2.7%

Tested-by: Haiwei Li <lihaiwei@tencent.com>
Cc: Haiwei Li <lihaiwei@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1588055009-12677-8-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

This commit is contained in:

Wanpeng Li 2020-05-06 11:44:01 -04:00 • committed by Paolo Bonzini

parent ae95f566b3

commit 26efe2fd92

1 changed files with 12 additions and 2 deletions

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arch/x86/kvm/vmx/vmx.c

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