diff options
| -rw-r--r-- | arch/mips/kvm/emulate.c | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index b37954c..ab5681d 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -302,12 +302,31 @@ static inline ktime_t kvm_mips_count_time(struct kvm_vcpu *vcpu) */ static uint32_t kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now) { - ktime_t expires; + struct mips_coproc *cop0 = vcpu->arch.cop0; + ktime_t expires, threshold; + uint32_t count, compare; int running; - /* Is the hrtimer pending? */ + /* Calculate the biased and scaled guest CP0_Count */ + count = vcpu->arch.count_bias + kvm_mips_ktime_to_count(vcpu, now); + compare = kvm_read_c0_guest_compare(cop0); + + /* + * Find whether CP0_Count has reached the closest timer interrupt. If + * not, we shouldn't inject it. + */ + if ((int32_t)(count - compare) < 0) + return count; + + /* + * The CP0_Count we're going to return has already reached the closest + * timer interrupt. Quickly check if it really is a new interrupt by + * looking at whether the interval until the hrtimer expiry time is + * less than 1/4 of the timer period. + */ expires = hrtimer_get_expires(&vcpu->arch.comparecount_timer); - if (ktime_compare(now, expires) >= 0) { + threshold = ktime_add_ns(now, vcpu->arch.count_period / 4); + if (ktime_before(expires, threshold)) { /* * Cancel it while we handle it so there's no chance of * interference with the timeout handler. @@ -329,8 +348,7 @@ static uint32_t kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now) } } - /* Return the biased and scaled guest CP0_Count */ - return vcpu->arch.count_bias + kvm_mips_ktime_to_count(vcpu, now); + return count; } /** |