diff options
Diffstat (limited to 'arch/mips/kvm/kvm_mips_emul.c')
| -rw-r--r-- | arch/mips/kvm/kvm_mips_emul.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c index 65c8dea6d1f5..6d257384c9b4 100644 --- a/arch/mips/kvm/kvm_mips_emul.c +++ b/arch/mips/kvm/kvm_mips_emul.c @@ -498,6 +498,54 @@ void kvm_mips_init_count(struct kvm_vcpu *vcpu) } /** + * kvm_mips_set_count_hz() - Update the frequency of the timer. + * @vcpu: Virtual CPU. + * @count_hz: Frequency of CP0_Count timer in Hz. + * + * Change the frequency of the CP0_Count timer. This is done atomically so that + * CP0_Count is continuous and no timer interrupt is lost. + * + * Returns: -EINVAL if @count_hz is out of range. + * 0 on success. + */ +int kvm_mips_set_count_hz(struct kvm_vcpu *vcpu, s64 count_hz) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + int dc; + ktime_t now; + u32 count; + + /* ensure the frequency is in a sensible range... */ + if (count_hz <= 0 || count_hz > NSEC_PER_SEC) + return -EINVAL; + /* ... and has actually changed */ + if (vcpu->arch.count_hz == count_hz) + return 0; + + /* Safely freeze timer so we can keep it continuous */ + dc = kvm_mips_count_disabled(vcpu); + if (dc) { + now = kvm_mips_count_time(vcpu); + count = kvm_read_c0_guest_count(cop0); + } else { + now = kvm_mips_freeze_hrtimer(vcpu, &count); + } + + /* Update the frequency */ + vcpu->arch.count_hz = count_hz; + vcpu->arch.count_period = div_u64((u64)NSEC_PER_SEC << 32, count_hz); + vcpu->arch.count_dyn_bias = 0; + + /* Calculate adjusted bias so dynamic count is unchanged */ + vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now); + + /* Update and resume hrtimer */ + if (!dc) + kvm_mips_resume_hrtimer(vcpu, now, count); + return 0; +} + +/** * kvm_mips_write_compare() - Modify compare and update timer. * @vcpu: Virtual CPU. * @compare: New CP0_Compare value. |