kvm/x86: Hyper-V synthetic interrupt controller

SynIC (synthetic interrupt controller) is a lapic extension,
which is controlled via MSRs and maintains for each vCPU
 - 16 synthetic interrupt "lines" (SINT's); each can be configured to
   trigger a specific interrupt vector optionally with auto-EOI
   semantics
 - a message page in the guest memory with 16 256-byte per-SINT message
   slots
 - an event flag page in the guest memory with 16 2048-bit per-SINT
   event flag areas

The host triggers a SINT whenever it delivers a new message to the
corresponding slot or flips an event flag bit in the corresponding area.
The guest informs the host that it can try delivering a message by
explicitly asserting EOI in lapic or writing to End-Of-Message (EOM)
MSR.

The userspace (qemu) triggers interrupts and receives EOM notifications
via irqfd with resampler; for that, a GSI is allocated for each
configured SINT, and irq_routing api is extended to support GSI-SINT
mapping.

Changes v4:
* added activation of SynIC by vcpu KVM_ENABLE_CAP
* added per SynIC active flag
* added deactivation of APICv upon SynIC activation

Changes v3:
* added KVM_CAP_HYPERV_SYNIC and KVM_IRQ_ROUTING_HV_SINT notes into
docs

Changes v2:
* do not use posted interrupts for Hyper-V SynIC AutoEOI vectors
* add Hyper-V SynIC vectors into EOI exit bitmap
* Hyper-V SyniIC SINT msr write logic simplified

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>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 03f3618..27ce460 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -831,6 +831,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_GUEST_DEBUG_HW_WPS 120
 #define KVM_CAP_SPLIT_IRQCHIP 121
 #define KVM_CAP_IOEVENTFD_ANY_LENGTH 122
+#define KVM_CAP_HYPERV_SYNIC 123
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -854,10 +855,16 @@ struct kvm_irq_routing_s390_adapter {
 	__u32 adapter_id;
 };
 
+struct kvm_irq_routing_hv_sint {
+	__u32 vcpu;
+	__u32 sint;
+};
+
 /* gsi routing entry types */
 #define KVM_IRQ_ROUTING_IRQCHIP 1
 #define KVM_IRQ_ROUTING_MSI 2
 #define KVM_IRQ_ROUTING_S390_ADAPTER 3
+#define KVM_IRQ_ROUTING_HV_SINT 4
 
 struct kvm_irq_routing_entry {
 	__u32 gsi;
@@ -868,6 +875,7 @@ struct kvm_irq_routing_entry {
 		struct kvm_irq_routing_irqchip irqchip;
 		struct kvm_irq_routing_msi msi;
 		struct kvm_irq_routing_s390_adapter adapter;
+		struct kvm_irq_routing_hv_sint hv_sint;
 		__u32 pad[8];
 	} u;
 };