[Devel] [PATCH RHEL7 COMMIT] ms/kvm/x86: Hyper-V HV_X64_MSR_RESET msr

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-327.4.5.vz7.11.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.4.5.vz7.11.2
------>
commit 7ace63707ac5d1204769c55800cd4c834b07db3b
Author: Andrey Smetanin <asmetanin at virtuozzo.com>
Date:   Tue Feb 16 13:50:10 2016 +0400

    ms/kvm/x86: Hyper-V HV_X64_MSR_RESET msr
    
    HV_X64_MSR_RESET msr is used by Hyper-V based Windows guest
    to reset guest VM by hypervisor.
    
    Necessary to support loading of winhv.sys in guest, which in turn is
    required to support Windows VMBus.
    
    ms commit e516cebb4f2b2057a5a421fea589079502acfff6.
    
    Signed-off-by: Andrey Smetanin <asmetanin at virtuozzo.com>
    
    Reviewed-by: Roman Kagan <rkagan at virtuozzo.com>
    Signed-off-by: Denis V. Lunev <den at openvz.org>
    CC: Paolo Bonzini <pbonzini at redhat.com>
    CC: Gleb Natapov <gleb at kernel.org>
    Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
---
 arch/x86/include/uapi/asm/hyperv.h |  3 +++
 arch/x86/kvm/hyperv.c              | 10 ++++++++++
 arch/x86/kvm/x86.c                 |  7 +++++++
 include/linux/kvm_host.h           |  1 +
 4 files changed, 21 insertions(+)

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index ccb24e6..7fcd585 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -149,6 +149,9 @@
 /* MSR used to provide vcpu index */
 #define HV_X64_MSR_VP_INDEX			0x40000002
 
+/* MSR used to reset the guest OS. */
+#define HV_X64_MSR_RESET			0x40000003
+
 /* MSR used to read the per-partition time reference counter */
 #define HV_X64_MSR_TIME_REF_COUNT		0x40000020
 
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 02c58b4..dae37ba 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -41,6 +41,7 @@ static bool kvm_hv_msr_partition_wide(u32 msr)
 	case HV_X64_MSR_TIME_REF_COUNT:
 	case HV_X64_MSR_CRASH_CTL:
 	case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
+	case HV_X64_MSR_RESET:
 		r = true;
 		break;
 	}
@@ -163,6 +164,12 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
 						 data);
 	case HV_X64_MSR_CRASH_CTL:
 		return kvm_hv_msr_set_crash_ctl(vcpu, data, host);
+	case HV_X64_MSR_RESET:
+		if (data == 1) {
+			vcpu_debug(vcpu, "hyper-v reset requested\n");
+			kvm_make_request(KVM_REQ_HV_RESET, vcpu);
+		}
+		break;
 	default:
 		vcpu_unimpl(vcpu, "Hyper-V uhandled wrmsr: 0x%x data 0x%llx\n",
 			    msr, data);
@@ -241,6 +248,9 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 						 pdata);
 	case HV_X64_MSR_CRASH_CTL:
 		return kvm_hv_msr_get_crash_ctl(vcpu, pdata);
+	case HV_X64_MSR_RESET:
+		data = 0;
+		break;
 	default:
 		vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
 		return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7649178..19897d9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -939,6 +939,7 @@ static u32 emulated_msrs[] = {
 	HV_X64_MSR_TIME_REF_COUNT, HV_X64_MSR_REFERENCE_TSC,
 	HV_X64_MSR_CRASH_P0, HV_X64_MSR_CRASH_P1, HV_X64_MSR_CRASH_P2,
 	HV_X64_MSR_CRASH_P3, HV_X64_MSR_CRASH_P4, HV_X64_MSR_CRASH_CTL,
+	HV_X64_MSR_RESET,
 	HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
 	MSR_KVM_PV_EOI_EN,
 
@@ -6350,6 +6351,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			r = 0;
 			goto out;
 		}
+		if (kvm_check_request(KVM_REQ_HV_RESET, vcpu)) {
+			vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+			vcpu->run->system_event.type = KVM_SYSTEM_EVENT_RESET;
+			r = 0;
+			goto out;
+		}
 	}
 
 	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d93356a5..3b05609 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -142,6 +142,7 @@ static inline bool is_error_page(struct page *page)
 #define KVM_REQ_APIC_PAGE_RELOAD  25
 #define KVM_REQ_SMI               26
 #define KVM_REQ_HV_CRASH          27
+#define KVM_REQ_HV_RESET          29
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID		0
 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID	1