kvm/x86: Hyper-V kvm exit

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.

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@virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Roman Kagan <rkagan@virtuozzo.com>
CC: Denis V. Lunev <den@openvz.org>
CC: qemu-devel@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 88af84675af0fdbbbe13cb40d3f5bb3cc5e12875..053f613fc9a913af132da7f794742c45d6727dfc 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3337,6 +3337,28 @@ the userspace IOAPIC should process the EOI and retrigger the interrupt if
 it is still asserted.  Vector is the LAPIC interrupt vector for which the
 EOI was received.
 
+               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 bab47b61d2b01df81c818610b6f90055a27e6d80..f608e170ba3d00393020d98e56ead0fd330dcb44 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -393,6 +393,7 @@ 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 83a3c0c9b3ded9b0eedf32d93d0283dcded387c8..41869a9d43f8b043193411ebb11990c9c901a932 100644 (file)
--- 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 eb64377edcd30b0cfcde8f405e936b410fed7f53..036e4bc124f9105a289291e6414dbefea15d87b4 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6482,6 +6482,12 @@ 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;
+               }
        }
 
        /*

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ebaf2f82f712471236dddccb5f9c0e97a134e84f..14f95969b0f372a6cf3c49fa17be727d7742c8dc 100644 (file)
--- 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_HV_CRASH          27
 #define KVM_REQ_IOAPIC_EOI_EXIT   28
 #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 27ce4602a072e255d4d1fe0df04bafa06d92e8aa..6e32f75990818ee1d2379196c9be1647721fe380 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -154,6 +154,20 @@ struct kvm_s390_skeys {
        __u32 flags;
        __u32 reserved[9];
 };
+
+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_S390_GET_SKEYS_NONE   1
 #define KVM_S390_SKEYS_MAX        1048576
 
@@ -184,6 +198,7 @@ struct kvm_s390_skeys {
 #define KVM_EXIT_SYSTEM_EVENT     24
 #define KVM_EXIT_S390_STSI        25
 #define KVM_EXIT_IOAPIC_EOI       26
+#define KVM_EXIT_HYPERV           27
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -338,6 +353,8 @@ struct kvm_run {
                struct {
                        __u8 vector;
                } eoi;
+               /* KVM_EXIT_HYPERV */
+               struct kvm_hyperv_exit hyperv;
                /* Fix the size of the union. */
                char padding[256];
        };