Re: [Qemu-devel] [PATCH v3 9/9] kvm/x86: Hyper-V kvm exit

[Andrey Smetanin <asmetanin@virtuozzo.com>]

On 11/03/2015 04:28 PM, Paolo Bonzini wrote:
>
>
> On 22/10/2015 18:10, Andrey Smetanin wrote:
>> 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 v3:
>> * added KVM_EXIT_HYPERV types and structs notes into docs
>>
>> Signed-off-by: Andrey Smetanin <asmetanin@virtuozzo.com>
>> Reviewed-by: Roman Kagan <rkagan@virtiozzo.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@virtiozzo.com>
>>
>> ---
>>   Documentation/virtual/kvm/api.txt | 22 ++++++++++++++++++++++
>>   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, 64 insertions(+)
>>
>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
>> index 8710418..a6858eb 100644
>> --- 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 8434f88..54c90d3 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(&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)
>>   {
>> @@ -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);
>
> Another note.  I am getting:
>
> EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000663
> ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
> EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
> ES =0000 00000000 0000ffff 00009300
> CS =f000 ffff0000 0000ffff 00009b00
> SS =0000 00000000 0000ffff 00009300
> DS =0000 00000000 0000ffff 00009300
> FS =0000 00000000 0000ffff 00009300
> GS =0000 00000000 0000ffff 00009300
> LDT=0000 00000000 0000ffff 00008200
> TR =0000 00000000 0000ffff 00008b00
> GDT=     00000000 0000ffff
> IDT=     00000000 0000ffff
> CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
> DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
> DR3=0000000000000000
> DR6=00000000ffff0ff0 DR7=0000000000000400
> EFER=0000000000000000
> Code=90 90 90 90 eb c3 90 90 90 90 90 90 00 00 00 00 56 54 46 00 <90> 90
> eb ac 90 90 90 90 90 90 90 90 90 90 90 90 00 00 00 00 00 00 00 00 00 00
> 00 00 00 00
>
> if I run a patched QEMU but I *do not* enable the synthetic interrupt
> controller.  I can fix it by wrapping the calls to synic_exit with "if
> (!host)", but I haven't checked yet the source---so that may not be the
> proper fix.  Sorry for not having looked more in detail.
>
> Paolo
>
Thank you, we will test and resend correct version.
>>   		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 b853b2df..0704ee3 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_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 27ce460..6e32f75 100644
>> --- 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];
>>   	};
>>