Re: [PATCH v3 8/9] kvm/x86: Hyper-V synthetic interrupt controller

[Paolo Bonzini <pbonzini@redhat.com>]

Hi Andrey,

just one question.  Is kvm_arch_set_irq actually needed?  I think
everything should work fine without it.  Can you check?  If so, I can
remove it myself and revert the patch that introduced the hook.

Paolo

On 22/10/2015 18:09, Andrey Smetanin wrote:
> 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.
> 
> 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: Vitaly Kuznetsov <vkuznets@redhat.com>
> CC: "K. Y. Srinivasan" <kys@microsoft.com>
> CC: Gleb Natapov <gleb@kernel.org>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Roman Kagan <rkagan@virtuozzo.com>
> 
> 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
> ---
>  Documentation/virtual/kvm/api.txt |  14 ++
>  arch/x86/include/asm/kvm_host.h   |  14 ++
>  arch/x86/kvm/hyperv.c             | 297 ++++++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/hyperv.h             |  21 +++
>  arch/x86/kvm/irq_comm.c           |  34 +++++
>  arch/x86/kvm/lapic.c              |  18 ++-
>  arch/x86/kvm/lapic.h              |   5 +
>  arch/x86/kvm/x86.c                |  12 +-
>  include/linux/kvm_host.h          |   6 +
>  include/uapi/linux/kvm.h          |   8 +
>  10 files changed, 421 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 092ee9f..8710418 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1451,6 +1451,7 @@ 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;
>  };
> @@ -1459,6 +1460,7 @@ struct kvm_irq_routing_entry {
>  #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
>  
>  No flags are specified so far, the corresponding field must be set to zero.
>  
> @@ -1482,6 +1484,10 @@ struct kvm_irq_routing_s390_adapter {
>  	__u32 adapter_id;
>  };
>  
> +struct kvm_irq_routing_hv_sint {
> +	__u32 vcpu;
> +	__u32 sint;
> +};
>  
>  4.53 KVM_ASSIGN_SET_MSIX_NR (deprecated)
>  
> @@ -3685,3 +3691,11 @@ available, means that that the kernel has an implementation of the
>  H_RANDOM hypercall backed by a hardware random-number generator.
>  If present, the kernel H_RANDOM handler can be enabled for guest use
>  with the KVM_CAP_PPC_ENABLE_HCALL capability.
> +
> +8.2 KVM_CAP_HYPERV_SYNIC
> +
> +Architectures: x86
> +This capability, if KVM_CHECK_EXTENSION indicates that it is
> +available, means that that the kernel has an implementation of the
> +Hyper-V Synthetic interrupt controller(SynIC). SynIC is used to
> +support Windows Hyper-V based guest paravirt drivers(VMBus).
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 3c6327d..8434f88 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -25,6 +25,7 @@
>  #include <linux/pvclock_gtod.h>
>  #include <linux/clocksource.h>
>  #include <linux/irqbypass.h>
> +#include <linux/hyperv.h>
>  
>  #include <asm/pvclock-abi.h>
>  #include <asm/desc.h>
> @@ -374,10 +375,23 @@ struct kvm_mtrr {
>  	struct list_head head;
>  };
>  
> +/* Hyper-V synthetic interrupt controller (SynIC)*/
> +struct kvm_vcpu_hv_synic {
> +	u64 version;
> +	u64 control;
> +	u64 msg_page;
> +	u64 evt_page;
> +	atomic64_t sint[HV_SYNIC_SINT_COUNT];
> +	atomic_t sint_to_gsi[HV_SYNIC_SINT_COUNT];
> +	DECLARE_BITMAP(auto_eoi_bitmap, 256);
> +	DECLARE_BITMAP(vec_bitmap, 256);
> +};
> +
>  /* Hyper-V per vcpu emulation context */
>  struct kvm_vcpu_hv {
>  	u64 hv_vapic;
>  	s64 runtime_offset;
> +	struct kvm_vcpu_hv_synic synic;
>  };
>  
>  struct kvm_vcpu_arch {
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index 62cf8c9..8ff71f3 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -23,13 +23,296 @@
>  
>  #include "x86.h"
>  #include "lapic.h"
> +#include "ioapic.h"
>  #include "hyperv.h"
>  
>  #include <linux/kvm_host.h>
> +#include <asm/apicdef.h>
>  #include <trace/events/kvm.h>
>  
>  #include "trace.h"
>  
> +static inline u64 synic_read_sint(struct kvm_vcpu_hv_synic *synic, int sint)
> +{
> +	return atomic64_read(&synic->sint[sint]);
> +}
> +
> +static inline int synic_get_sint_vector(u64 sint_value)
> +{
> +	if (sint_value & HV_SYNIC_SINT_MASKED)
> +		return -1;
> +	return sint_value & HV_SYNIC_SINT_VECTOR_MASK;
> +}
> +
> +static bool synic_has_vector_connected(struct kvm_vcpu_hv_synic *synic,
> +				      int vector)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
> +		if (synic_get_sint_vector(synic_read_sint(synic, i)) == vector)
> +			return true;
> +	}
> +	return false;
> +}
> +
> +static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic,
> +				     int vector)
> +{
> +	int i;
> +	u64 sint_value;
> +
> +	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
> +		sint_value = synic_read_sint(synic, i);
> +		if (synic_get_sint_vector(sint_value) == vector &&
> +		    sint_value & HV_SYNIC_SINT_AUTO_EOI)
> +			return true;
> +	}
> +	return false;
> +}
> +
> +static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, u64 data)
> +{
> +	int vector;
> +
> +	vector = data & HV_SYNIC_SINT_VECTOR_MASK;
> +	if (vector < 16)
> +		return 1;
> +	/*
> +	 * Guest may configure multiple SINTs to use the same vector, so
> +	 * we maintain a bitmap of vectors handled by synic, and a
> +	 * bitmap of vectors with auto-eoi behavior.  The bitmaps are
> +	 * updated here, and atomically queried on fast paths.
> +	 */
> +
> +	atomic64_set(&synic->sint[sint], data);
> +
> +	if (synic_has_vector_connected(synic, vector))
> +		__set_bit(vector, synic->vec_bitmap);
> +	else
> +		__clear_bit(vector, synic->vec_bitmap);
> +
> +	if (synic_has_vector_auto_eoi(synic, vector))
> +		__set_bit(vector, synic->auto_eoi_bitmap);
> +	else
> +		__clear_bit(vector, synic->auto_eoi_bitmap);
> +
> +	/* Load SynIC vectors into EOI exit bitmap */
> +	kvm_make_request(KVM_REQ_SCAN_IOAPIC, synic_to_vcpu(synic));
> +	return 0;
> +}
> +
> +static struct kvm_vcpu_hv_synic *synic_get(struct kvm *kvm, u32 vcpu_id)
> +{
> +	struct kvm_vcpu *vcpu;
> +
> +	if (vcpu_id >= atomic_read(&kvm->online_vcpus))
> +		return NULL;
> +	vcpu = kvm_get_vcpu(kvm, vcpu_id);
> +	if (!vcpu)
> +		return NULL;
> +
> +	return vcpu_to_synic(vcpu);
> +}
> +
> +static void kvm_hv_notify_acked_sint(struct kvm_vcpu *vcpu, u32 sint)
> +{
> +	struct kvm *kvm = vcpu->kvm;
> +	int gsi, idx;
> +
> +	vcpu_debug(vcpu, "Hyper-V SynIC acked sint %d\n", sint);
> +
> +	idx = srcu_read_lock(&kvm->irq_srcu);
> +	gsi = atomic_read(&vcpu_to_synic(vcpu)->sint_to_gsi[sint]);
> +	if (gsi != -1)
> +		kvm_notify_acked_gsi(kvm, gsi);
> +	srcu_read_unlock(&kvm->irq_srcu, idx);
> +}
> +
> +static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
> +			 u32 msr, u64 data, bool host)
> +{
> +	struct kvm_vcpu *vcpu = synic_to_vcpu(synic);
> +	int ret;
> +
> +	vcpu_debug(vcpu, "Hyper-V SynIC set msr 0x%x 0x%llx host %d\n",
> +		   msr, data, host);
> +	ret = 0;
> +	switch (msr) {
> +	case HV_X64_MSR_SCONTROL:
> +		synic->control = data;
> +		break;
> +	case HV_X64_MSR_SVERSION:
> +		if (!host) {
> +			ret = 1;
> +			break;
> +		}
> +		synic->version = data;
> +		break;
> +	case HV_X64_MSR_SIEFP:
> +		if (data & HV_SYNIC_SIEFP_ENABLE)
> +			if (kvm_clear_guest(vcpu->kvm,
> +					    data & PAGE_MASK, PAGE_SIZE)) {
> +				ret = 1;
> +				break;
> +			}
> +		synic->evt_page = data;
> +		break;
> +	case HV_X64_MSR_SIMP:
> +		if (data & HV_SYNIC_SIMP_ENABLE)
> +			if (kvm_clear_guest(vcpu->kvm,
> +					    data & PAGE_MASK, PAGE_SIZE)) {
> +				ret = 1;
> +				break;
> +			}
> +		synic->msg_page = data;
> +		break;
> +	case HV_X64_MSR_EOM: {
> +		int i;
> +
> +		for (i = 0; i < ARRAY_SIZE(synic->sint); i++)
> +			kvm_hv_notify_acked_sint(vcpu, i);
> +		break;
> +	}
> +	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
> +		ret = synic_set_sint(synic, msr - HV_X64_MSR_SINT0, data);
> +		break;
> +	default:
> +		ret = 1;
> +		break;
> +	}
> +	return ret;
> +}
> +
> +static int synic_get_msr(struct kvm_vcpu_hv_synic *synic, u32 msr, u64 *pdata)
> +{
> +	int ret;
> +
> +	ret = 0;
> +	switch (msr) {
> +	case HV_X64_MSR_SCONTROL:
> +		*pdata = synic->control;
> +		break;
> +	case HV_X64_MSR_SVERSION:
> +		*pdata = synic->version;
> +		break;
> +	case HV_X64_MSR_SIEFP:
> +		*pdata = synic->evt_page;
> +		break;
> +	case HV_X64_MSR_SIMP:
> +		*pdata = synic->msg_page;
> +		break;
> +	case HV_X64_MSR_EOM:
> +		*pdata = 0;
> +		break;
> +	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
> +		*pdata = atomic64_read(&synic->sint[msr - HV_X64_MSR_SINT0]);
> +		break;
> +	default:
> +		ret = 1;
> +		break;
> +	}
> +	return ret;
> +}
> +
> +int synic_set_irq(struct kvm_vcpu_hv_synic *synic, u32 sint)
> +{
> +	struct kvm_vcpu *vcpu = synic_to_vcpu(synic);
> +	struct kvm_lapic_irq irq;
> +	int ret, vector;
> +
> +	if (sint >= ARRAY_SIZE(synic->sint))
> +		return -EINVAL;
> +
> +	vector = synic_get_sint_vector(synic_read_sint(synic, sint));
> +	if (vector < 0)
> +		return -ENOENT;
> +
> +	memset(&irq, 0, sizeof(irq));
> +	irq.dest_id = kvm_apic_id(vcpu->arch.apic);
> +	irq.dest_mode = APIC_DEST_PHYSICAL;
> +	irq.delivery_mode = APIC_DM_FIXED;
> +	irq.vector = vector;
> +	irq.level = 1;
> +
> +	ret = kvm_irq_delivery_to_apic(vcpu->kvm, NULL, &irq, NULL);
> +	vcpu_debug(vcpu, "Hyper-V SynIC set irq ret %d\n", ret);
> +	return ret;
> +}
> +
> +int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint)
> +{
> +	struct kvm_vcpu_hv_synic *synic;
> +
> +	synic = synic_get(kvm, vcpu_id);
> +	if (!synic)
> +		return -EINVAL;
> +
> +	return synic_set_irq(synic, sint);
> +}
> +
> +void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector)
> +{
> +	struct kvm_vcpu_hv_synic *synic = vcpu_to_synic(vcpu);
> +	int i;
> +
> +	vcpu_debug(vcpu, "Hyper-V SynIC send eoi vec %d\n", vector);
> +
> +	for (i = 0; i < ARRAY_SIZE(synic->sint); i++)
> +		if (synic_get_sint_vector(synic_read_sint(synic, i)) == vector)
> +			kvm_hv_notify_acked_sint(vcpu, i);
> +}
> +
> +static int kvm_hv_set_sint_gsi(struct kvm *kvm, u32 vcpu_id, u32 sint, int gsi)
> +{
> +	struct kvm_vcpu_hv_synic *synic;
> +
> +	synic = synic_get(kvm, vcpu_id);
> +	if (!synic)
> +		return -EINVAL;
> +
> +	if (sint >= ARRAY_SIZE(synic->sint_to_gsi))
> +		return -EINVAL;
> +
> +	atomic_set(&synic->sint_to_gsi[sint], gsi);
> +	return 0;
> +}
> +
> +void kvm_hv_irq_routing_update(struct kvm *kvm)
> +{
> +	struct kvm_irq_routing_table *irq_rt;
> +	struct kvm_kernel_irq_routing_entry *e;
> +	u32 gsi;
> +
> +	irq_rt = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu,
> +					lockdep_is_held(&kvm->irq_lock));
> +
> +	for (gsi = 0; gsi < irq_rt->nr_rt_entries; gsi++) {
> +		hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
> +			if (e->type == KVM_IRQ_ROUTING_HV_SINT)
> +				kvm_hv_set_sint_gsi(kvm, e->hv_sint.vcpu,
> +						    e->hv_sint.sint, gsi);
> +		}
> +	}
> +}
> +
> +static void synic_init(struct kvm_vcpu_hv_synic *synic)
> +{
> +	int i;
> +
> +	memset(synic, 0, sizeof(*synic));
> +	synic->version = HV_SYNIC_VERSION_1;
> +	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
> +		atomic64_set(&synic->sint[i], HV_SYNIC_SINT_MASKED);
> +		atomic_set(&synic->sint_to_gsi[i], -1);
> +	}
> +}
> +
> +void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
> +{
> +	synic_init(vcpu_to_synic(vcpu));
> +}
> +
>  static bool kvm_hv_msr_partition_wide(u32 msr)
>  {
>  	bool r = false;
> @@ -226,6 +509,13 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
>  			return 1;
>  		hv->runtime_offset = data - current_task_runtime_100ns();
>  		break;
> +	case HV_X64_MSR_SCONTROL:
> +	case HV_X64_MSR_SVERSION:
> +	case HV_X64_MSR_SIEFP:
> +	case HV_X64_MSR_SIMP:
> +	case HV_X64_MSR_EOM:
> +	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
> +		return synic_set_msr(vcpu_to_synic(vcpu), msr, data, host);
>  	default:
>  		vcpu_unimpl(vcpu, "Hyper-V uhandled wrmsr: 0x%x data 0x%llx\n",
>  			    msr, data);
> @@ -304,6 +594,13 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
>  	case HV_X64_MSR_VP_RUNTIME:
>  		data = current_task_runtime_100ns() + hv->runtime_offset;
>  		break;
> +	case HV_X64_MSR_SCONTROL:
> +	case HV_X64_MSR_SVERSION:
> +	case HV_X64_MSR_SIEFP:
> +	case HV_X64_MSR_SIMP:
> +	case HV_X64_MSR_EOM:
> +	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
> +		return synic_get_msr(vcpu_to_synic(vcpu), msr, pdata);
>  	default:
>  		vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
>  		return 1;
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index c7bce55..8668612 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -29,4 +29,25 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
>  bool kvm_hv_hypercall_enabled(struct kvm *kvm);
>  int kvm_hv_hypercall(struct kvm_vcpu *vcpu);
>  
> +int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint);
> +void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector);
> +
> +static inline struct kvm_vcpu_hv_synic *vcpu_to_synic(struct kvm_vcpu *vcpu)
> +{
> +	return &vcpu->arch.hyperv.synic;
> +}
> +
> +static inline struct kvm_vcpu *synic_to_vcpu(struct kvm_vcpu_hv_synic *synic)
> +{
> +	struct kvm_vcpu_hv *hv;
> +	struct kvm_vcpu_arch *arch;
> +
> +	hv = container_of(synic, struct kvm_vcpu_hv, synic);
> +	arch = container_of(hv, struct kvm_vcpu_arch, hyperv);
> +	return container_of(arch, struct kvm_vcpu, arch);
> +}
> +void kvm_hv_irq_routing_update(struct kvm *kvm);
> +
> +void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu);
> +
>  #endif
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> index fe91f72..5e195b9 100644
> --- a/arch/x86/kvm/irq_comm.c
> +++ b/arch/x86/kvm/irq_comm.c
> @@ -33,6 +33,8 @@
>  
>  #include "lapic.h"
>  
> +#include "hyperv.h"
> +
>  static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
>  			   struct kvm *kvm, int irq_source_id, int level,
>  			   bool line_status)
> @@ -251,6 +253,16 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, unsigned irqchip, unsigned pin,
>  	srcu_read_unlock(&kvm->irq_srcu, idx);
>  }
>  
> +static int kvm_hv_set_sint(struct kvm_kernel_irq_routing_entry *e,
> +		    struct kvm *kvm, int irq_source_id, int level,
> +		    bool line_status)
> +{
> +	if (!level)
> +		return -1;
> +
> +	return kvm_hv_synic_set_irq(kvm, e->hv_sint.vcpu, e->hv_sint.sint);
> +}
> +
>  int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
>  			  const struct kvm_irq_routing_entry *ue)
>  {
> @@ -289,6 +301,11 @@ int kvm_set_routing_entry(struct kvm_kernel_irq_routing_entry *e,
>  		e->msi.address_hi = ue->u.msi.address_hi;
>  		e->msi.data = ue->u.msi.data;
>  		break;
> +	case KVM_IRQ_ROUTING_HV_SINT:
> +		e->set = kvm_hv_set_sint;
> +		e->hv_sint.vcpu = ue->u.hv_sint.vcpu;
> +		e->hv_sint.sint = ue->u.hv_sint.sint;
> +		break;
>  	default:
>  		goto out;
>  	}
> @@ -405,3 +422,20 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
>  	}
>  	srcu_read_unlock(&kvm->irq_srcu, idx);
>  }
> +
> +int kvm_arch_set_irq(struct kvm_kernel_irq_routing_entry *irq, struct kvm *kvm,
> +		     int irq_source_id, int level, bool line_status)
> +{
> +	switch (irq->type) {
> +	case KVM_IRQ_ROUTING_HV_SINT:
> +		return kvm_hv_set_sint(irq, kvm, irq_source_id, level,
> +				       line_status);
> +	default:
> +		return -EWOULDBLOCK;
> +	}
> +}
> +
> +void kvm_arch_irq_routing_update(struct kvm *kvm)
> +{
> +	kvm_hv_irq_routing_update(kvm);
> +}
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index dc03a01..3132478 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -41,6 +41,7 @@
>  #include "trace.h"
>  #include "x86.h"
>  #include "cpuid.h"
> +#include "hyperv.h"
>  
>  #ifndef CONFIG_X86_64
>  #define mod_64(x, y) ((x) - (y) * div64_u64(x, y))
> @@ -128,11 +129,6 @@ static inline int apic_enabled(struct kvm_lapic *apic)
>  	(LVT_MASK | APIC_MODE_MASK | APIC_INPUT_POLARITY | \
>  	 APIC_LVT_REMOTE_IRR | APIC_LVT_LEVEL_TRIGGER)
>  
> -static inline int kvm_apic_id(struct kvm_lapic *apic)
> -{
> -	return (kvm_apic_get_reg(apic, APIC_ID) >> 24) & 0xff;
> -}
> -
>  /* The logical map is definitely wrong if we have multiple
>   * modes at the same time.  (Physical map is always right.)
>   */
> @@ -850,7 +846,8 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
>  				apic_clear_vector(vector, apic->regs + APIC_TMR);
>  		}
>  
> -		if (kvm_x86_ops->deliver_posted_interrupt)
> +		if (kvm_x86_ops->deliver_posted_interrupt &&
> +		    !test_bit(vector, vcpu_to_synic(vcpu)->auto_eoi_bitmap))
>  			kvm_x86_ops->deliver_posted_interrupt(vcpu, vector);
>  		else {
>  			apic_set_irr(vector, apic);
> @@ -972,6 +969,9 @@ static int apic_set_eoi(struct kvm_lapic *apic)
>  	apic_clear_isr(vector, apic);
>  	apic_update_ppr(apic);
>  
> +	if (test_bit(vector, vcpu_to_synic(apic->vcpu)->vec_bitmap))
> +		kvm_hv_synic_send_eoi(apic->vcpu, vector);
> +
>  	kvm_ioapic_send_eoi(apic, vector);
>  	kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
>  	return vector;
> @@ -1881,6 +1881,12 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu)
>  	apic_set_isr(vector, apic);
>  	apic_update_ppr(apic);
>  	apic_clear_irr(vector, apic);
> +
> +	if (test_bit(vector, vcpu_to_synic(vcpu)->auto_eoi_bitmap)) {
> +		apic_clear_isr(vector, apic);
> +		apic_update_ppr(apic);
> +	}
> +
>  	return vector;
>  }
>  
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index fde8e35d..6c64090 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -164,6 +164,11 @@ static inline int kvm_lapic_latched_init(struct kvm_vcpu *vcpu)
>  	return kvm_vcpu_has_lapic(vcpu) && test_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
>  }
>  
> +static inline int kvm_apic_id(struct kvm_lapic *apic)
> +{
> +	return (kvm_apic_get_reg(apic, APIC_ID) >> 24) & 0xff;
> +}
> +
>  bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
>  
>  void wait_lapic_expire(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fb6cfbf..b853b2df 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -959,6 +959,7 @@ static u32 emulated_msrs[] = {
>  	HV_X64_MSR_RESET,
>  	HV_X64_MSR_VP_INDEX,
>  	HV_X64_MSR_VP_RUNTIME,
> +	HV_X64_MSR_SCONTROL,
>  	HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
>  	MSR_KVM_PV_EOI_EN,
>  
> @@ -2441,6 +2442,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_HYPERV:
>  	case KVM_CAP_HYPERV_VAPIC:
>  	case KVM_CAP_HYPERV_SPIN:
> +	case KVM_CAP_HYPERV_SYNIC:
>  	case KVM_CAP_PCI_SEGMENT:
>  	case KVM_CAP_DEBUGREGS:
>  	case KVM_CAP_X86_ROBUST_SINGLESTEP:
> @@ -6195,6 +6197,8 @@ static void process_smi(struct kvm_vcpu *vcpu)
>  
>  static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
>  {
> +	u64 eoi_exit_bitmap[4];
> +
>  	if (!kvm_apic_hw_enabled(vcpu->arch.apic))
>  		return;
>  
> @@ -6205,8 +6209,10 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
>  	else
>  		kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
>  
> -	kvm_x86_ops->load_eoi_exitmap(vcpu,
> -				      (u64 *)vcpu->arch.ioapic_handled_vectors);
> +	bitmap_or((ulong *)eoi_exit_bitmap, vcpu->arch.ioapic_handled_vectors,
> +		  vcpu_to_synic(vcpu)->vec_bitmap, 256);
> +
> +	kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
>  }
>  
>  static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu)
> @@ -7456,6 +7462,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>  
>  	vcpu->arch.pending_external_vector = -1;
>  
> +	kvm_hv_vcpu_init(vcpu);
> +
>  	return 0;
>  
>  fail_free_mce_banks:
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index c742e79..43b0141 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -318,6 +318,11 @@ struct kvm_s390_adapter_int {
>  	u32 adapter_id;
>  };
>  
> +struct kvm_hv_sint {
> +	u32 vcpu;
> +	u32 sint;
> +};
> +
>  struct kvm_kernel_irq_routing_entry {
>  	u32 gsi;
>  	u32 type;
> @@ -331,6 +336,7 @@ struct kvm_kernel_irq_routing_entry {
>  		} irqchip;
>  		struct msi_msg msi;
>  		struct kvm_s390_adapter_int adapter;
> +		struct kvm_hv_sint hv_sint;
>  	};
>  	struct hlist_node link;
>  };
> 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;
>  };
>