[Devel] [PATCH rh7 v1 17/36] ms/kvm/x86: Hyper-V kvm exit

Andrey Smetanin asmetanin at virtuozzo.com
Wed Feb 10 07:17:39 PST 2016


A new vcpu exit is introduced to notify the userspace of the
changes in Hyper-V SynIC configuration triggered by guest writing to the
corresponding MSRs.

ms commit - db3975717ac5e2c2761bae7b90c4f2e0abb5ef22.

Changes v4:
* exit into userspace only if guest writes into SynIC MSR's

Changes v3:
* added KVM_EXIT_HYPERV types and structs notes into docs

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: Gleb Natapov <gleb at kernel.org>
CC: Paolo Bonzini <pbonzini at redhat.com>
CC: Roman Kagan <rkagan at virtuozzo.com>
CC: Denis V. Lunev <den at openvz.org>
CC: qemu-devel at nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
---
 Documentation/virtual/kvm/api.txt | 22 ++++++++++++++++++++++
 arch/x86/include/asm/kvm_host.h   |  1 +
 arch/x86/kvm/hyperv.c             | 20 ++++++++++++++++++++
 arch/x86/kvm/x86.c                |  6 ++++++
 include/linux/kvm_host.h          |  1 +
 include/uapi/linux/kvm.h          | 16 ++++++++++++++++
 6 files changed, 66 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index cd4abe5..bccc810 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2889,6 +2889,28 @@ HVC instruction based PSCI call from the vcpu. The 'type' field describes
 the system-level event type. The 'flags' field describes architecture
 specific flags for the system-level event.
 
+		struct kvm_hyperv_exit {
+#define KVM_EXIT_HYPERV_SYNIC          1
+			__u32 type;
+			union {
+				struct {
+					__u32 msr;
+					__u64 control;
+					__u64 evt_page;
+					__u64 msg_page;
+				} synic;
+			} u;
+		};
+		/* KVM_EXIT_HYPERV */
+                struct kvm_hyperv_exit hyperv;
+Indicates that the VCPU exits into userspace to process some tasks
+related to Hyper-V emulation.
+Valid values for 'type' are:
+	KVM_EXIT_HYPERV_SYNIC -- synchronously notify user-space about
+Hyper-V SynIC state change. Notification is used to remap SynIC
+event/message pages and to enable/disable SynIC messages/events processing
+in userspace.
+
 		/* Fix the size of the union. */
 		char padding[256];
 	};
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 83ef655..bb05bd1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -357,6 +357,7 @@ struct kvm_vcpu_hv {
 	u64 hv_vapic;
 	s64 runtime_offset;
 	struct kvm_vcpu_hv_synic synic;
+	struct kvm_hyperv_exit exit;
 };
 
 struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 83a3c0c..41869a9 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -130,6 +130,20 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu *vcpu, u32 sint)
 	srcu_read_unlock(&kvm->irq_srcu, idx);
 }
 
+static void synic_exit(struct kvm_vcpu_hv_synic *synic, u32 msr)
+{
+	struct kvm_vcpu *vcpu = synic_to_vcpu(synic);
+	struct kvm_vcpu_hv *hv_vcpu = &vcpu->arch.hyperv;
+
+	hv_vcpu->exit.type = KVM_EXIT_HYPERV_SYNIC;
+	hv_vcpu->exit.u.synic.msr = msr;
+	hv_vcpu->exit.u.synic.control = synic->control;
+	hv_vcpu->exit.u.synic.evt_page = synic->evt_page;
+	hv_vcpu->exit.u.synic.msg_page = synic->msg_page;
+
+	kvm_make_request(KVM_REQ_HV_EXIT, vcpu);
+}
+
 static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 			 u32 msr, u64 data, bool host)
 {
@@ -145,6 +159,8 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 	switch (msr) {
 	case HV_X64_MSR_SCONTROL:
 		synic->control = data;
+		if (!host)
+			synic_exit(synic, msr);
 		break;
 	case HV_X64_MSR_SVERSION:
 		if (!host) {
@@ -161,6 +177,8 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 				break;
 			}
 		synic->evt_page = data;
+		if (!host)
+			synic_exit(synic, msr);
 		break;
 	case HV_X64_MSR_SIMP:
 		if (data & HV_SYNIC_SIMP_ENABLE)
@@ -170,6 +188,8 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 				break;
 			}
 		synic->msg_page = data;
+		if (!host)
+			synic_exit(synic, msr);
 		break;
 	case HV_X64_MSR_EOM: {
 		int i;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0442be5..2b7c4fc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6401,6 +6401,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			r = 0;
 			goto out;
 		}
+		if (kvm_check_request(KVM_REQ_HV_EXIT, vcpu)) {
+			vcpu->run->exit_reason = KVM_EXIT_HYPERV;
+			vcpu->run->hyperv = vcpu->arch.hyperv.exit;
+			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 e31d468..b0fa329 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -143,6 +143,7 @@ static inline bool is_error_page(struct page *page)
 #define KVM_REQ_SMI               26
 #define KVM_REQ_HV_CRASH          27
 #define KVM_REQ_HV_RESET          29
+#define KVM_REQ_HV_EXIT           30
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID		0
 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID	1
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 34bcea5..158391b 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -147,6 +147,19 @@ struct kvm_pit_config {
 
 #define KVM_PIT_SPEAKER_DUMMY     1
 
+struct kvm_hyperv_exit {
+#define KVM_EXIT_HYPERV_SYNIC          1
+	__u32 type;
+	union {
+		struct {
+			__u32 msr;
+			__u64 control;
+			__u64 evt_page;
+			__u64 msg_page;
+		} synic;
+	} u;
+};
+
 #define KVM_EXIT_UNKNOWN          0
 #define KVM_EXIT_EXCEPTION        1
 #define KVM_EXIT_IO               2
@@ -172,6 +185,7 @@ struct kvm_pit_config {
 #define KVM_EXIT_S390_TSCH        22
 #define KVM_EXIT_EPR              23
 #define KVM_EXIT_SYSTEM_EVENT     24
+#define KVM_EXIT_HYPERV           27
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -310,6 +324,8 @@ struct kvm_run {
 			__u32 type;
 			__u64 flags;
 		} system_event;
+		/* KVM_EXIT_HYPERV */
+		struct kvm_hyperv_exit hyperv;
 		/* Fix the size of the union. */
 		char padding[256];
 	};
-- 
2.4.3



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