diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/x86.c | 75 |
1 files changed, 62 insertions, 13 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b08812d6b34..63a77caa59f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -492,8 +492,8 @@ static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data) static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) { static int version; - struct kvm_wall_clock wc; - struct timespec wc_ts; + struct pvclock_wall_clock wc; + struct timespec now, sys, boot; if (!wall_clock) return; @@ -502,10 +502,19 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) kvm_write_guest(kvm, wall_clock, &version, sizeof(version)); - wc_ts = current_kernel_time(); - wc.wc_sec = wc_ts.tv_sec; - wc.wc_nsec = wc_ts.tv_nsec; - wc.wc_version = version; + /* + * The guest calculates current wall clock time by adding + * system time (updated by kvm_write_guest_time below) to the + * wall clock specified here. guest system time equals host + * system time for us, thus we must fill in host boot time here. + */ + now = current_kernel_time(); + ktime_get_ts(&sys); + boot = ns_to_timespec(timespec_to_ns(&now) - timespec_to_ns(&sys)); + + wc.sec = boot.tv_sec; + wc.nsec = boot.tv_nsec; + wc.version = version; kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc)); @@ -513,6 +522,45 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) kvm_write_guest(kvm, wall_clock, &version, sizeof(version)); } +static uint32_t div_frac(uint32_t dividend, uint32_t divisor) +{ + uint32_t quotient, remainder; + + /* Don't try to replace with do_div(), this one calculates + * "(dividend << 32) / divisor" */ + __asm__ ( "divl %4" + : "=a" (quotient), "=d" (remainder) + : "0" (0), "1" (dividend), "r" (divisor) ); + return quotient; +} + +static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info *hv_clock) +{ + uint64_t nsecs = 1000000000LL; + int32_t shift = 0; + uint64_t tps64; + uint32_t tps32; + + tps64 = tsc_khz * 1000LL; + while (tps64 > nsecs*2) { + tps64 >>= 1; + shift--; + } + + tps32 = (uint32_t)tps64; + while (tps32 <= (uint32_t)nsecs) { + tps32 <<= 1; + shift++; + } + + hv_clock->tsc_shift = shift; + hv_clock->tsc_to_system_mul = div_frac(nsecs, tps32); + + pr_debug("%s: tsc_khz %u, tsc_shift %d, tsc_mul %u\n", + __FUNCTION__, tsc_khz, hv_clock->tsc_shift, + hv_clock->tsc_to_system_mul); +} + static void kvm_write_guest_time(struct kvm_vcpu *v) { struct timespec ts; @@ -523,6 +571,11 @@ static void kvm_write_guest_time(struct kvm_vcpu *v) if ((!vcpu->time_page)) return; + if (unlikely(vcpu->hv_clock_tsc_khz != tsc_khz)) { + kvm_set_time_scale(tsc_khz, &vcpu->hv_clock); + vcpu->hv_clock_tsc_khz = tsc_khz; + } + /* Keep irq disabled to prevent changes to the clock */ local_irq_save(flags); kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER, @@ -537,14 +590,14 @@ static void kvm_write_guest_time(struct kvm_vcpu *v) /* * The interface expects us to write an even number signaling that the * update is finished. Since the guest won't see the intermediate - * state, we just write "2" at the end + * state, we just increase by 2 at the end. */ - vcpu->hv_clock.version = 2; + vcpu->hv_clock.version += 2; shared_kaddr = kmap_atomic(vcpu->time_page, KM_USER0); memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, - sizeof(vcpu->hv_clock)); + sizeof(vcpu->hv_clock)); kunmap_atomic(shared_kaddr, KM_USER0); @@ -599,10 +652,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) /* ...but clean it before doing the actual write */ vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); - vcpu->arch.hv_clock.tsc_to_system_mul = - clocksource_khz2mult(tsc_khz, 22); - vcpu->arch.hv_clock.tsc_shift = 22; - down_read(¤t->mm->mmap_sem); vcpu->arch.time_page = gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); |