KVM: X86: Provide a capability to disable HLT intercepts
If host CPUs are dedicated to a VM, we can avoid VM exits on HLT. This patch adds the per-VM capability to disable them. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Jan H. Schönherr <jschoenh@amazon.de> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Paolo Bonzini

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@@ -4367,6 +4367,7 @@ Returns: 0 on success, -EINVAL when args[0] contains invalid exits
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Valid bits in args[0] are
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#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
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#define KVM_X86_DISABLE_EXITS_HLT (1 << 1)
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Enabling this capability on a VM provides userspace with a way to no
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longer intercept some instructions for improved latency in some
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@@ -4375,6 +4376,7 @@ physical CPUs. More bits can be added in the future; userspace can
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just pass the KVM_CHECK_EXTENSION result to KVM_ENABLE_CAP to disable
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all such vmexits.
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Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits.
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8. Other capabilities.
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----------------------
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