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KVM: arm/arm64: Enable adaptative WFE trapping

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Trapping blocking WFE is extremely beneficial in situations where
the system is oversubscribed, as it allows another thread to run
while being blocked. In a non-oversubscribed environment, this is
the complete opposite, and trapping WFE is just unnecessary overhead.

Let's only enable WFE trapping if the CPU has more than a single task
to run (that is, more than just the vcpu thread).

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier
2018-06-21 10:43:59 +01:00
parent 0a72a5ab9f
commit de73708915
3 changed files with 26 additions and 0 deletions
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10
arch/arm64/include/asm/kvm_emulate.h
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@@ -83,6 +83,16 @@ static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)
return (unsigned long *)&vcpu->arch.hcr_el2;
}
static inline void vcpu_clear_wfe_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 &= ~HCR_TWE;
}
static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 |= HCR_TWE;
}
static inline void vcpu_set_vsesr(struct kvm_vcpu *vcpu, u64 vsesr)
{
vcpu->arch.vsesr_el2 = vsesr;