5 files changed, 80 insertions, 4 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 67d19e422006..a1f0b5dd7d75 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -363,6 +363,8 @@ struct kvm_vcpu_arch {
         /* used for guest single stepping over the given code position */
         u16 singlestep_cs;
         unsigned long singlestep_rip;
+        /* fields used by HYPER-V emulation */
+        u64 hv_vapic;
 };
 
 struct kvm_mem_alias {
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ba8c045da782..4b224f90087b 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1246,3 +1246,34 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
 
         return 0;
 }
+
+int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 reg, u64 data)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+
+        if (!irqchip_in_kernel(vcpu->kvm))
+                return 1;
+
+        /* if this is ICR write vector before command */
+        if (reg == APIC_ICR)
+                apic_reg_write(apic, APIC_ICR2, (u32)(data >> 32));
+        return apic_reg_write(apic, reg, (u32)data);
+}
+
+int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 reg, u64 *data)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+        u32 low, high = 0;
+
+        if (!irqchip_in_kernel(vcpu->kvm))
+                return 1;
+
+        if (apic_reg_read(apic, reg, 4, &low))
+                return 1;
+        if (reg == APIC_ICR)
+                apic_reg_read(apic, APIC_ICR2, 4, &high);
+
+        *data = (((u64)high) << 32) | low;
+
+        return 0;
+}
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 40010b09c4aa..f5fe32c5edad 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -48,4 +48,12 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu);
 
 int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data);
 int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data);
+
+int kvm_hv_vapic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data);
+int kvm_hv_vapic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data);
+
+static inline bool kvm_hv_vapic_assist_page_enabled(struct kvm_vcpu *vcpu)
+{
+        return vcpu->arch.hv_vapic & HV_X64_MSR_APIC_ASSIST_PAGE_ENABLE;
+}
 #endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 480137db4770..552be51e4d84 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -622,10 +622,11 @@ static inline u32 bit(int bitno)
  * kvm-specific. Those are put in the beginning of the list.
  */
 
-#define KVM_SAVE_MSRS_BEGIN     4
+#define KVM_SAVE_MSRS_BEGIN     5
 static u32 msrs_to_save[] = {
         MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
         HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
+        HV_X64_MSR_APIC_ASSIST_PAGE,
         MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
         MSR_K6_STAR,
 #ifdef CONFIG_X86_64
@@ -1067,10 +1068,36 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 
 static int set_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
-        pr_unimpl(vcpu, "HYPER-V unimplemented wrmsr: 0x%x data 0x%llx\n",
-                  msr, data);
+        switch (msr) {
+        case HV_X64_MSR_APIC_ASSIST_PAGE: {
+                unsigned long addr;
 
-        return 1;
+                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;
 }
 
 int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
@@ -1330,6 +1357,12 @@ static int get_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
                                 data = r;
                 break;
         }
+        case HV_X64_MSR_EOI:
+                return kvm_hv_vapic_msr_read(vcpu, APIC_EOI, pdata);
+        case HV_X64_MSR_ICR:
+                return kvm_hv_vapic_msr_read(vcpu, APIC_ICR, pdata);
+        case HV_X64_MSR_TPR:
+                return kvm_hv_vapic_msr_read(vcpu, APIC_TASKPRI, pdata);
         default:
                 pr_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
                 return 1;
@@ -1530,6 +1563,7 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_ADJUST_CLOCK:
         case KVM_CAP_VCPU_EVENTS:
         case KVM_CAP_HYPERV:
+        case KVM_CAP_HYPERV_VAPIC:
                 r = 1;
                 break;
         case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index e227cbae70ad..5ce61738dc30 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -498,6 +498,7 @@ struct kvm_ioeventfd {
 #define KVM_CAP_S390_PSW 42
 #define KVM_CAP_PPC_SEGSTATE 43
 #define KVM_CAP_HYPERV 44
+#define KVM_CAP_HYPERV_VAPIC 45
 
 #ifdef KVM_CAP_IRQ_ROUTING