diff options
Diffstat (limited to 'arch/mips/kvm/kvm_mips_emul.c')
| -rw-r--r-- | arch/mips/kvm/kvm_mips_emul.c | 132 |
1 files changed, 120 insertions, 12 deletions
diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c index 088c25d73a11..65c8dea6d1f5 100644 --- a/arch/mips/kvm/kvm_mips_emul.c +++ b/arch/mips/kvm/kvm_mips_emul.c @@ -233,14 +233,15 @@ enum emulation_result update_pc(struct kvm_vcpu *vcpu, uint32_t cause) * kvm_mips_count_disabled() - Find whether the CP0_Count timer is disabled. * @vcpu: Virtual CPU. * - * Returns: 1 if the CP0_Count timer is disabled by the guest CP0_Cause.DC - * bit. + * Returns: 1 if the CP0_Count timer is disabled by either the guest + * CP0_Cause.DC bit or the count_ctl.DC bit. * 0 otherwise (in which case CP0_Count timer is running). */ static inline int kvm_mips_count_disabled(struct kvm_vcpu *vcpu) { struct mips_coproc *cop0 = vcpu->arch.cop0; - return kvm_read_c0_guest_cause(cop0) & CAUSEF_DC; + return (vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) || + (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC); } /** @@ -280,6 +281,24 @@ static uint32_t kvm_mips_ktime_to_count(struct kvm_vcpu *vcpu, ktime_t now) } /** + * kvm_mips_count_time() - Get effective current time. + * @vcpu: Virtual CPU. + * + * Get effective monotonic ktime. This is usually a straightforward ktime_get(), + * except when the master disable bit is set in count_ctl, in which case it is + * count_resume, i.e. the time that the count was disabled. + * + * Returns: Effective monotonic ktime for CP0_Count. + */ +static inline ktime_t kvm_mips_count_time(struct kvm_vcpu *vcpu) +{ + if (unlikely(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC)) + return vcpu->arch.count_resume; + + return ktime_get(); +} + +/** * kvm_mips_read_count_running() - Read the current count value as if running. * @vcpu: Virtual CPU. * @now: Kernel time to read CP0_Count at. @@ -448,7 +467,7 @@ void kvm_mips_write_count(struct kvm_vcpu *vcpu, uint32_t count) ktime_t now; /* Calculate bias */ - now = ktime_get(); + now = kvm_mips_count_time(vcpu); vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now); if (kvm_mips_count_disabled(vcpu)) @@ -508,8 +527,8 @@ void kvm_mips_write_compare(struct kvm_vcpu *vcpu, uint32_t compare) * Disable the CP0_Count timer. A timer interrupt on or before the final stop * time will be handled but not after. * - * Assumes CP0_Count was previously enabled but now Guest.CP0_Cause.DC has been - * set (count disabled). + * Assumes CP0_Count was previously enabled but now Guest.CP0_Cause.DC or + * count_ctl.DC has been set (count disabled). * * Returns: The time that the timer was stopped. */ @@ -535,7 +554,8 @@ static ktime_t kvm_mips_count_disable(struct kvm_vcpu *vcpu) * @vcpu: Virtual CPU. * * Disable the CP0_Count timer and set CP0_Cause.DC. A timer interrupt on or - * before the final stop time will be handled, but not after. + * before the final stop time will be handled if the timer isn't disabled by + * count_ctl.DC, but not after. * * Assumes CP0_Cause.DC is clear (count enabled). */ @@ -544,7 +564,8 @@ void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu) struct mips_coproc *cop0 = vcpu->arch.cop0; kvm_set_c0_guest_cause(cop0, CAUSEF_DC); - kvm_mips_count_disable(vcpu); + if (!(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC)) + kvm_mips_count_disable(vcpu); } /** @@ -552,9 +573,9 @@ void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu) * @vcpu: Virtual CPU. * * Enable the CP0_Count timer and clear CP0_Cause.DC. A timer interrupt after - * the start time will be handled, potentially before even returning, so the - * caller should be careful with ordering of CP0_Cause modifications so as not - * to lose it. + * the start time will be handled if the timer isn't disabled by count_ctl.DC, + * potentially before even returning, so the caller should be careful with + * ordering of CP0_Cause modifications so as not to lose it. * * Assumes CP0_Cause.DC is set (count disabled). */ @@ -567,13 +588,100 @@ void kvm_mips_count_enable_cause(struct kvm_vcpu *vcpu) /* * Set the dynamic count to match the static count. - * This starts the hrtimer. + * This starts the hrtimer if count_ctl.DC allows it. + * Otherwise it conveniently updates the biases. */ count = kvm_read_c0_guest_count(cop0); kvm_mips_write_count(vcpu, count); } /** + * kvm_mips_set_count_ctl() - Update the count control KVM register. + * @vcpu: Virtual CPU. + * @count_ctl: Count control register new value. + * + * Set the count control KVM register. The timer is updated accordingly. + * + * Returns: -EINVAL if reserved bits are set. + * 0 on success. + */ +int kvm_mips_set_count_ctl(struct kvm_vcpu *vcpu, s64 count_ctl) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + s64 changed = count_ctl ^ vcpu->arch.count_ctl; + s64 delta; + ktime_t expire, now; + uint32_t count, compare; + + /* Only allow defined bits to be changed */ + if (changed & ~(s64)(KVM_REG_MIPS_COUNT_CTL_DC)) + return -EINVAL; + + /* Apply new value */ + vcpu->arch.count_ctl = count_ctl; + + /* Master CP0_Count disable */ + if (changed & KVM_REG_MIPS_COUNT_CTL_DC) { + /* Is CP0_Cause.DC already disabling CP0_Count? */ + if (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC) { + if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) + /* Just record the current time */ + vcpu->arch.count_resume = ktime_get(); + } else if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) { + /* disable timer and record current time */ + vcpu->arch.count_resume = kvm_mips_count_disable(vcpu); + } else { + /* + * Calculate timeout relative to static count at resume + * time (wrap 0 to 2^32). + */ + count = kvm_read_c0_guest_count(cop0); + compare = kvm_read_c0_guest_compare(cop0); + delta = (u64)(uint32_t)(compare - count - 1) + 1; + delta = div_u64(delta * NSEC_PER_SEC, + vcpu->arch.count_hz); + expire = ktime_add_ns(vcpu->arch.count_resume, delta); + + /* Handle pending interrupt */ + now = ktime_get(); + if (ktime_compare(now, expire) >= 0) + /* Nothing should be waiting on the timeout */ + kvm_mips_callbacks->queue_timer_int(vcpu); + + /* Resume hrtimer without changing bias */ + count = kvm_mips_read_count_running(vcpu, now); + kvm_mips_resume_hrtimer(vcpu, now, count); + } + } + + return 0; +} + +/** + * kvm_mips_set_count_resume() - Update the count resume KVM register. + * @vcpu: Virtual CPU. + * @count_resume: Count resume register new value. + * + * Set the count resume KVM register. + * + * Returns: -EINVAL if out of valid range (0..now). + * 0 on success. + */ +int kvm_mips_set_count_resume(struct kvm_vcpu *vcpu, s64 count_resume) +{ + /* + * It doesn't make sense for the resume time to be in the future, as it + * would be possible for the next interrupt to be more than a full + * period in the future. + */ + if (count_resume < 0 || count_resume > ktime_to_ns(ktime_get())) + return -EINVAL; + + vcpu->arch.count_resume = ns_to_ktime(count_resume); + return 0; +} + +/** * kvm_mips_count_timeout() - Push timer forward on timeout. * @vcpu: Virtual CPU. * |