diff options
| -rw-r--r-- | arch/x86/kvm/xen.c | 65 |
1 files changed, 60 insertions, 5 deletions
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index a909b817b9c0..300a79f1fae5 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -150,11 +150,46 @@ static enum hrtimer_restart xen_timer_callback(struct hrtimer *timer) return HRTIMER_NORESTART; } +static int xen_get_guest_pvclock(struct kvm_vcpu *vcpu, + struct pvclock_vcpu_time_info *hv_clock, + struct gfn_to_pfn_cache *gpc, + unsigned int offset) +{ + unsigned long flags; + int r; + + read_lock_irqsave(&gpc->lock, flags); + while (!kvm_gpc_check(gpc, offset + sizeof(*hv_clock))) { + read_unlock_irqrestore(&gpc->lock, flags); + + r = kvm_gpc_refresh(gpc, offset + sizeof(*hv_clock)); + if (r) + return r; + + read_lock_irqsave(&gpc->lock, flags); + } + + memcpy(hv_clock, gpc->khva + offset, sizeof(*hv_clock)); + read_unlock_irqrestore(&gpc->lock, flags); + + /* + * Sanity check TSC shift+multiplier to verify the guest's view of time + * is more or less consistent. + */ + if (hv_clock->tsc_shift != vcpu->arch.hv_clock.tsc_shift || + hv_clock->tsc_to_system_mul != vcpu->arch.hv_clock.tsc_to_system_mul) + return -EINVAL; + + return 0; +} + static void kvm_xen_start_timer(struct kvm_vcpu *vcpu, u64 guest_abs, bool linux_wa) { + struct kvm_vcpu_xen *xen = &vcpu->arch.xen; int64_t kernel_now, delta; uint64_t guest_now; + int r = -EOPNOTSUPP; /* * The guest provides the requested timeout in absolute nanoseconds @@ -173,10 +208,29 @@ static void kvm_xen_start_timer(struct kvm_vcpu *vcpu, u64 guest_abs, * the absolute CLOCK_MONOTONIC time at which the timer should * fire. */ - if (vcpu->arch.hv_clock.version && vcpu->kvm->arch.use_master_clock && - static_cpu_has(X86_FEATURE_CONSTANT_TSC)) { + do { + struct pvclock_vcpu_time_info hv_clock; uint64_t host_tsc, guest_tsc; + if (!static_cpu_has(X86_FEATURE_CONSTANT_TSC) || + !vcpu->kvm->arch.use_master_clock) + break; + + /* + * If both Xen PV clocks are active, arbitrarily try to use the + * compat clock first, but also try to use the non-compat clock + * if the compat clock is unusable. The two PV clocks hold the + * same information, but it's possible one (or both) is stale + * and/or currently unreachable. + */ + if (xen->vcpu_info_cache.active) + r = xen_get_guest_pvclock(vcpu, &hv_clock, &xen->vcpu_info_cache, + offsetof(struct compat_vcpu_info, time)); + if (r && xen->vcpu_time_info_cache.active) + r = xen_get_guest_pvclock(vcpu, &hv_clock, &xen->vcpu_time_info_cache, 0); + if (r) + break; + if (!IS_ENABLED(CONFIG_64BIT) || !kvm_get_monotonic_and_clockread(&kernel_now, &host_tsc)) { /* @@ -197,9 +251,10 @@ static void kvm_xen_start_timer(struct kvm_vcpu *vcpu, u64 guest_abs, /* Calculate the guest kvmclock as the guest would do it. */ guest_tsc = kvm_read_l1_tsc(vcpu, host_tsc); - guest_now = __pvclock_read_cycles(&vcpu->arch.hv_clock, - guest_tsc); - } else { + guest_now = __pvclock_read_cycles(&hv_clock, guest_tsc); + } while (0); + + if (r) { /* * Without CONSTANT_TSC, get_kvmclock_ns() is the only option. * |