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| author | Marc Zyngier <marc.zyngier@arm.com> | 2018-06-21 12:43:59 +0300 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-07-09 13:38:24 +0300 |
| commit | de73708915adc1b3f05e617a86da6b2d68fae141 (patch) | |
| tree | 37f70c868acf33f7645e67c42b599cd5034614c4 | |
| parent | 0a72a5ab9feb8ba6101b00bbcac14cdbae1d1df7 (diff) | |
| download | linux-de73708915adc1b3f05e617a86da6b2d68fae141.tar.xz | |
KVM: arm/arm64: Enable adaptative WFE trapping
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>
| -rw-r--r-- | arch/arm/include/asm/kvm_emulate.h | 10 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_emulate.h | 10 | ||||
| -rw-r--r-- | virt/kvm/arm/arm.c | 6 |
3 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h index 6493bd479ddc..b50fe8380868 100644 --- a/arch/arm/include/asm/kvm_emulate.h +++ b/arch/arm/include/asm/kvm_emulate.h @@ -107,6 +107,16 @@ static inline unsigned long *vcpu_hcr(const struct kvm_vcpu *vcpu) return (unsigned long *)&vcpu->arch.hcr; } +static inline void vcpu_clear_wfe_traps(struct kvm_vcpu *vcpu) +{ + vcpu->arch.hcr &= ~HCR_TWE; +} + +static inline void vcpu_set_wfe_traps(struct kvm_vcpu *vcpu) +{ + vcpu->arch.hcr |= HCR_TWE; +} + static inline bool vcpu_mode_is_32bit(const struct kvm_vcpu *vcpu) { return 1; diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index dd98fdf33d99..bfefdd9a72eb 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -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; diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 04e554cae3a2..8e66b89a3db2 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -30,6 +30,7 @@ #include <linux/kvm.h> #include <linux/kvm_irqfd.h> #include <linux/irqbypass.h> +#include <linux/sched/stat.h> #include <trace/events/kvm.h> #include <kvm/arm_pmu.h> #include <kvm/arm_psci.h> @@ -380,6 +381,11 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) kvm_timer_vcpu_load(vcpu); kvm_vcpu_load_sysregs(vcpu); kvm_arch_vcpu_load_fp(vcpu); + + if (single_task_running()) + vcpu_clear_wfe_traps(vcpu); + else + vcpu_set_wfe_traps(vcpu); } void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) |