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| author | Christoffer Dall <christoffer.dall@linaro.org> | 2015-08-25 17:48:21 (GMT) |
|---|---|---|
| committer | Christoffer Dall <christoffer.dall@linaro.org> | 2015-10-22 21:01:42 (GMT) |
| commit | d35268da66870d733ae763fd7f9b06a1f63f395e (patch) | |
| tree | 408e3ad5ebdc30184c149c065aea29d0bc066f07 /arch | |
| parent | 3217f7c25bca66eed9b07f0b8bfd1937169b0736 (diff) | |
| download | linux-d35268da66870d733ae763fd7f9b06a1f63f395e.tar.xz | |
arm/arm64: KVM: arch_timer: Only schedule soft timer on vcpu_block
We currently schedule a soft timer every time we exit the guest if the
timer did not expire while running the guest. This is really not
necessary, because the only work we do in the timer work function is to
kick the vcpu.
Kicking the vcpu does two things:
(1) If the vpcu thread is on a waitqueue, make it runnable and remove it
from the waitqueue.
(2) If the vcpu is running on a different physical CPU from the one
doing the kick, it sends a reschedule IPI.
The second case cannot happen, because the soft timer is only ever
scheduled when the vcpu is not running. The first case is only relevant
when the vcpu thread is on a waitqueue, which is only the case when the
vcpu thread has called kvm_vcpu_block().
Therefore, we only need to make sure a timer is scheduled for
kvm_vcpu_block(), which we do by encapsulating all calls to
kvm_vcpu_block() with kvm_timer_{un}schedule calls.
Additionally, we only schedule a soft timer if the timer is enabled and
unmasked, since it is useless otherwise.
Note that theoretically userspace can use the SET_ONE_REG interface to
change registers that should cause the timer to fire, even if the vcpu
is blocked without a scheduled timer, but this case was not supported
before this patch and we leave it for future work for now.
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/kvm_host.h | 3 | ||||
| -rw-r--r-- | arch/arm/kvm/arm.c | 10 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 3 |
3 files changed, 10 insertions, 6 deletions
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 84da979..c4072d9 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -234,7 +234,4 @@ static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} - #endif /* __ARM_KVM_HOST_H__ */ diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 78b2869..7ed4d47 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -271,6 +271,16 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) return kvm_timer_should_fire(vcpu); } +void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) +{ + kvm_timer_schedule(vcpu); +} + +void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) +{ + kvm_timer_unschedule(vcpu); +} + int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) { /* Force users to call KVM_ARM_VCPU_INIT */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e4f4d65..ed03968 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -255,7 +255,4 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); -static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {} -static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {} - #endif /* __ARM64_KVM_HOST_H__ */ |