u64 options;
};
+/* Current state of Hyper-V TSC page clocksource */
+enum hv_tsc_page_status {
+ /* TSC page was not set up or disabled */
+ HV_TSC_PAGE_UNSET = 0,
+ /* TSC page MSR was written by the guest, update pending */
+ HV_TSC_PAGE_GUEST_CHANGED,
+ /* TSC page MSR was written by KVM userspace, update pending */
+ HV_TSC_PAGE_HOST_CHANGED,
+ /* TSC page was properly set up and is currently active */
+ HV_TSC_PAGE_SET,
+ /* TSC page is currently being updated and therefore is inactive */
+ HV_TSC_PAGE_UPDATING,
+ /* TSC page was set up with an inaccessible GPA */
+ HV_TSC_PAGE_BROKEN,
+};
+
/* Hyper-V emulation context */
struct kvm_hv {
struct mutex hv_lock;
u64 hv_guest_os_id;
u64 hv_hypercall;
u64 hv_tsc_page;
+ enum hv_tsc_page_status hv_tsc_page_status;
/* Hyper-v based guest crash (NT kernel bugcheck) parameters */
u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
u64 tsc;
/*
- * The guest has not set up the TSC page or the clock isn't
- * stable, fall back to get_kvmclock_ns.
+ * Fall back to get_kvmclock_ns() when TSC page hasn't been set up,
+ * is broken, disabled or being updated.
*/
- if (!hv->tsc_ref.tsc_sequence)
+ if (hv->hv_tsc_page_status != HV_TSC_PAGE_SET)
return div_u64(get_kvmclock_ns(kvm), 100);
vcpu = kvm_get_vcpu(kvm, 0);
BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);
- if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
+ if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
+ hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET)
return;
mutex_lock(&hv->hv_lock);
*/
if (unlikely(kvm_read_guest(kvm, gfn_to_gpa(gfn),
&tsc_seq, sizeof(tsc_seq))))
- goto out_unlock;
+ goto out_err;
/*
* While we're computing and writing the parameters, force the
hv->tsc_ref.tsc_sequence = 0;
if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
&hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
- goto out_unlock;
+ goto out_err;
if (!compute_tsc_page_parameters(hv_clock, &hv->tsc_ref))
- goto out_unlock;
+ goto out_err;
/* Ensure sequence is zero before writing the rest of the struct. */
smp_wmb();
if (kvm_write_guest(kvm, gfn_to_gpa(gfn), &hv->tsc_ref, sizeof(hv->tsc_ref)))
- goto out_unlock;
+ goto out_err;
/*
* Now switch to the TSC page mechanism by writing the sequence.
smp_wmb();
hv->tsc_ref.tsc_sequence = tsc_seq;
- kvm_write_guest(kvm, gfn_to_gpa(gfn),
- &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence));
+ if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
+ &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
+ goto out_err;
+
+ hv->hv_tsc_page_status = HV_TSC_PAGE_SET;
+ goto out_unlock;
+
+out_err:
+ hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN;
out_unlock:
mutex_unlock(&hv->hv_lock);
}
struct kvm_hv *hv = to_kvm_hv(kvm);
u64 gfn;
- if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
+ if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
+ hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET)
return;
mutex_lock(&hv->hv_lock);
if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
goto out_unlock;
+ /* Preserve HV_TSC_PAGE_GUEST_CHANGED/HV_TSC_PAGE_HOST_CHANGED states */
+ if (hv->hv_tsc_page_status == HV_TSC_PAGE_SET)
+ hv->hv_tsc_page_status = HV_TSC_PAGE_UPDATING;
+
gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
hv->tsc_ref.tsc_sequence = 0;
- kvm_write_guest(kvm, gfn_to_gpa(gfn),
- &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence));
+ if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
+ &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
+ hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN;
out_unlock:
mutex_unlock(&hv->hv_lock);
}
case HV_X64_MSR_REFERENCE_TSC:
hv->hv_tsc_page = data;
- if (hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE)
+ if (hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) {
+ if (!host)
+ hv->hv_tsc_page_status = HV_TSC_PAGE_GUEST_CHANGED;
+ else
+ hv->hv_tsc_page_status = HV_TSC_PAGE_HOST_CHANGED;
kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
+ } else {
+ hv->hv_tsc_page_status = HV_TSC_PAGE_UNSET;
+ }
break;
case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
return kvm_hv_msr_set_crash_data(kvm,