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KVM: X86: support paravirtualized help for TLB shootdowns

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When running on a virtual machine, IPIs are expensive when the target
CPU is sleeping.  Thus, it is nice to be able to avoid them for TLB
shootdowns.  KVM can just do the flush via INVVPID on the guest's behalf
the next time the CPU is scheduled.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[Use "&" to test the bit instead of "==". - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Wanpeng Li
2017-12-12 17:33:04 -08:00
committed by Radim Krčmář
parent c2ba05ccfd
commit f38a7b7526
2 changed files with 14 additions and 8 deletions
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3
arch/x86/kvm/cpuid.c
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@@ -602,7 +602,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
(1 << KVM_FEATURE_ASYNC_PF) |
(1 << KVM_FEATURE_PV_EOI) |
(1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
(1 << KVM_FEATURE_PV_UNHALT);
(1 << KVM_FEATURE_PV_UNHALT) |
(1 << KVM_FEATURE_PV_TLB_FLUSH);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);