[PATCH 9/9] kvm/x86: Hyper-V kvm exit

[Denis V. Lunev]

From: Andrey Smetanin 

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.

Signed-off-by: Andrey Smetanin 
Reviewed-by: Roman Kagan 
Signed-off-by: Denis V. Lunev 
CC: Vitaly Kuznetsov 
CC: "K. Y. Srinivasan" 
CC: Gleb Natapov 
CC: Paolo Bonzini 
---
 Documentation/virtual/kvm/api.txt |  6 ++
 arch/x86/include/asm/kvm_host.h   |  1 +
 arch/x86/kvm/hyperv.c | 17 +
 arch/x86/kvm/x86.c|  6 ++
 include/linux/kvm_host.h  |  1 +
 include/uapi/linux/kvm.h  | 17 +
 6 files changed, 48 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt 
b/Documentation/virtual/kvm/api.txt
index 092ee9f..86cae88 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3331,6 +3331,12 @@ 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.
 
+   /* KVM_EXIT_HYPERV */
+struct kvm_hyperv_exit hyperv;
+Indicates that the VCPU exits into userspace to process some tasks
+related with Hyper-V emulation. Currently used to synchronize modified
+Hyper-V SynIC state with 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 dfdaf0f..a41d7ed 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -392,6 +392,7 @@ 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 8ff71f3..9443920 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -129,6 +129,20 @@ static void kvm_hv_notify_acked_sint(struct kvm_vcpu 
*vcpu, u32 sint)
srcu_read_unlock(>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 = >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)
 {
@@ -141,6 +155,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
switch (msr) {
case HV_X64_MSR_SCONTROL:
synic->control = data;
+   synic_exit(synic, msr);
break;
case HV_X64_MSR_SVERSION:
if (!host) {
@@ -157,6 +172,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
break;
}
synic->evt_page = data;
+   synic_exit(synic, msr);
break;
case HV_X64_MSR_SIMP:
if (data & HV_SYNIC_SIMP_ENABLE)
@@ -166,6 +182,7 @@ static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
break;
}
synic->msg_page = data;
+   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 807d124..9453207 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6342,6 +6342,12 @@ 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 43b0141..e38ac16 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_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_ID0
 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID   1
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 27ce460..6e32f75 100644
--- 

Re: [PATCH 9/9] kvm/x86: Hyper-V kvm exit

[Paolo Bonzini]

On 16/10/2015 09:07, Denis V. Lunev wrote:
>  
> + /* KVM_EXIT_HYPERV */
> +struct kvm_hyperv_exit hyperv;
> +Indicates that the VCPU exits into userspace to process some tasks
> +related with Hyper-V emulation. Currently used to synchronize modified
> +Hyper-V SynIC state with userspace.
> +

The documentation should include the definition of the struct and the
definition of the subtypes (currently KVM_EXIT_HYPERV_SYNIC only).

Documentation for KVM_CAP_HYPERV_SINIC and KVM_IRQ_ROUTING_HV_SINT is
missing, too.

Finally, it would be better to have unit tests in kvm-unit-tests.
Either this or QEMU support is a requirement for merging, and the unit
tests are probably easier.

But apart from this, the series looks great and I'm already applying it
to kvm/queue so that it gets some more testing.

Paolo
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Re: [PATCH 9/9] kvm/x86: Hyper-V kvm exit

[Roman Kagan]

On Fri, Oct 16, 2015 at 09:51:58AM +0200, Paolo Bonzini wrote:
> The documentation should include the definition of the struct and the
> definition of the subtypes (currently KVM_EXIT_HYPERV_SYNIC only).
> 
> Documentation for KVM_CAP_HYPERV_SINIC and KVM_IRQ_ROUTING_HV_SINT is
> missing, too.
> 
> Finally, it would be better to have unit tests in kvm-unit-tests.
> Either this or QEMU support is a requirement for merging, and the unit
> tests are probably easier.

OK we'll try to get this done early next week.

Thanks,
Roman.
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