+static bool kvm_hv_hypercall_enabled(struct kvm *kvm)
+{
+ return kvm->arch.hv_hypercall & HV_X64_MSR_HYPERCALL_ENABLE;
+}
+
+static bool kvm_hv_msr_partition_wide(u32 msr)
+{
+ bool r = false;
+ switch (msr) {
+ case HV_X64_MSR_GUEST_OS_ID:
+ case HV_X64_MSR_HYPERCALL:
+ r = true;
+ break;
+ }
+
+ return r;
+}
+
+static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+ struct kvm *kvm = vcpu->kvm;
+
+ switch (msr) {
+ case HV_X64_MSR_GUEST_OS_ID:
+ kvm->arch.hv_guest_os_id = data;
+ /* setting guest os id to zero disables hypercall page */
+ if (!kvm->arch.hv_guest_os_id)
+ kvm->arch.hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE;
+ break;
+ case HV_X64_MSR_HYPERCALL: {
+ u64 gfn;
+ unsigned long addr;
+ u8 instructions[4];
+
+ /* if guest os id is not set hypercall should remain disabled */
+ if (!kvm->arch.hv_guest_os_id)
+ break;
+ if (!(data & HV_X64_MSR_HYPERCALL_ENABLE)) {
+ kvm->arch.hv_hypercall = data;
+ break;
+ }
+ gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
+ addr = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(addr))
+ return 1;
+ kvm_x86_ops->patch_hypercall(vcpu, instructions);
+ ((unsigned char *)instructions)[3] = 0xc3; /* ret */
+ if (copy_to_user((void __user *)addr, instructions, 4))
+ return 1;
+ kvm->arch.hv_hypercall = data;
+ break;
+ }
+ default:
+ pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x "
+ "data 0x%llx\n", msr, data);
+ return 1;
+ }
+ return 0;
+}
+
+static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+ switch (msr) {
+ case HV_X64_MSR_APIC_ASSIST_PAGE: {
+ unsigned long addr;
+
+ if (!(data & HV_X64_MSR_APIC_ASSIST_PAGE_ENABLE)) {
+ vcpu->arch.hv_vapic = data;
+ break;
+ }
+ addr = gfn_to_hva(vcpu->kvm, data >>
+ HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT);
+ if (kvm_is_error_hva(addr))
+ return 1;
+ if (clear_user((void __user *)addr, PAGE_SIZE))
+ return 1;
+ vcpu->arch.hv_vapic = data;
+ break;
+ }
+ case HV_X64_MSR_EOI:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_EOI, data);
+ case HV_X64_MSR_ICR:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_ICR, data);
+ case HV_X64_MSR_TPR:
+ return kvm_hv_vapic_msr_write(vcpu, APIC_TASKPRI, data);
+ default:
+ pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x "
+ "data 0x%llx\n", msr, data);
+ return 1;
+ }
+
+ return 0;
+}
+